Fruit Manufacturing

192 Fruit Manufacturing several production procedures effective for reducing EB reactions were published (Chobot and Horulaba, 1983), including the use of ascorbic acid and nitrogen (Fukutani et al., 1986), blanching of the pulp (McKenzie and Beveridge, 1988), and controlled pectolytic enzyme treatment (Gierschner and Baumann, 1988). Montgomery and Petropakis (1980) found that the amount of ascorbic acid required to prevent EB in pear juice is dependent on the length of time between milling and heating. 8.2.3. Effect of the Ascorbic Acid (AA) Content in Color Change As previously described ascorbic acid (AA) does not inhibit polyphenol oxidase directly but acts as a reducing compound and reduces the orthoquinones to dehydroxyphenols. This action will continue as long as the concentration of ascorbic acid is sufficient to maintain a low concentration of quinones. As the concentration of AA is decreased, the quinone concentration increases and causes the formation of the brown pigments. Sapers and Douglas (1987) studied the effectiveness of ascorbic acid (AA) in cut surfaces and apple and pear juices, finding that 40 ppm AA inhibited approximately 60% in raw Granny Smith juice, but only ffi20% in Red Delicious juice, after 90 min at 208C. Sapers and Douglas (1987) also evaluated the effectiveness of sodium bisulfite (NaHSO3) and ascorbic acid (AA) in cut surfaces and apple and pear juices. The authors found that EB in apple juice was completely inhibited by the addition of 10 ppm SO2. The effectiveness of ascorbic acid (AA) and erythorbic acid (EA) in inhibiting EB at cut surfaces of apple and in raw apple juice was determined by tristimulus colorimetry by Sapers and Ziolkowski (1987). Lozano et al. (1995) studied the color changes of apple pulp treated with the various AA concentrations at 188C (Fig. 8.8). They found three linear regions in the Hunter LÃ versus log t plot, and a very well-defined breaking point was observed at the point where the AA loses its inhibitory properties after which browning proceeds at the usual rate. Similar behavior was CIE L* 70 65 AA ppm 60 100 ppm 300 ppm 600 ppm 55 900 ppm 1200 ppm 50 45 40 35 30 10 100 1000 1 Time (min) Figure 8.8. Influence of ascorbic acid on enzymatic browning in apple pulp (Lozano et al., 1994) with permission.

8 . Inhibition and Control of Browning 193 200Time (min) (MA) 18؇C 175 Breaking point 150 t at L*max 125 100 75 50 25 0 0 2 4 6 8 10 12 14 AA levels (ppm) Figure 8.9. Time to reach LÃ ¼ 55 and breaking point (end of browning inhibition) for MA sample as related to AA concentration, at 188C (Lozano et al., 1994) with permission. reported by Matsui et al. (1957), studying the oxidative darkening during the processing of ‘‘natural apple juices.’’ Experimental breaking points as a function of AA levels are plotted in Fig. 8.9. The data in Fig. 8.9 indicate that the addition of AA at levels greater than 600 ppm results in a linear increase of the browning breaking point. Visual observation of apple pulp samples treated with AA by trained judges indicated that for LÃ values greater than 55 the browning can be considered unacceptable. Time required at 188C to attain this level at various AA amounts is also plotted in Fig. 8.9. These values indicate that overtreatment with AA (>600 ppm) will not proportionally increase the time required to reach a maximum level of browning for commercial acceptabil- ity. To make some contribution to processing of cloudy apple juice, experiments regarding prevention of EB by adding ascorbic acid were also carried out. When retention of apple pulp in maceration tanks is required, as in the case of cloudy juice production, the amount of ascorbic acid necessary to inhibit EB must be estimated in accordance with the maceration time and temperature. 8.2.4. Nonconventional Chemical Inhibition of EB Table 8.5 lists a selection of chemical methods commonly used to inhibit EB. However, many other nonconventional methods have been developed simultaneously. Vacuum and pressure infiltration were investigated (Sapers et al., 1989) as a means of applying ascorbate- or erythorbate-based EB inhibitors to apple cut surfaces. Apple plugs infiltrated at 34 kPa pressure showed more uniform uptake of treatment solution and less extensive water logging than plugs vacuum infiltrated at 169–980 mbar. Delicious and Wine- sap plugs and dice gained 3–7 days of storage life at 48C when treated by pressure infiltration, compared to dipping. However, infiltrated dice required dewatering by centrifugation or partial dehydration to prevent water logging. Red Delicious and Winesap plugs, dipped for 90 s in 0.8–1.6% solutions of AA or EA, showed longer lags before the onset of browning with the former compound. AA and EA were similar in the effectiveness in apple juice. Because the relative effectiveness of AA and EA depends on the system in which they are compared, the

194 Fruit Manufacturing Table 8.5. Classical chemical methods used for the inhibition of EB in selected fruits and fruit products. Fruit/product Inhibition method Comments Reference Apple (GD) N-acetyl-l-cysteine (25 mM). Treatment with 200 ppm chitosan Molnar-Perl and Apple (McItosh) Reduced glutathione (50 mM) Use of 1.14 mM inhibited Friedman (1990) Apple (GS) Chitosan EB for 6 h (equivalent Sapers (1991) Apple Ascorbyl-6-fatty acid esters to 0.02% ascorbic acid) Sapers et al. (1989) Apple juice 0.250% erythorbic acid Ascorbic acid derivatives Sapers and and dices 0.5% amylose sulfate, The inhibitory effect could be Ziolkowski (1987) Apple pulp enhanced by 0.5% citric acid Apple slices 0.5% xylen sulfate Va´ mos-Vigya´ zo´ Ascorbic acid 100 –1000 ppm, depending (1995) Avocado Ascorbic acid on the required breaking point Banana Lozano et al. (1994) Model apple and 4-hexylresorcinol Mixture of 0.01% 4-HR Luo and High pressure 800 MPa; 258C and 0.5% AA reduces juice solution l-cysteine EB as 0.1% SO2 Barbosa-Canovas Carambola slices (1996) Citric acid þ ascorbic acid 5 mM gives 100% inhibition Weemaes (1998) Pear juice Found oxidation depends Kahn (1985) (D’Anjou) l-cysteine Ascorbic acid (AA) Goupy et al. (1995) on total phenols Weller et al. (1997) Plum juice 0.5 mM cysteine, Treating slices with 1.0 or 2.5% 1.0 Na metabisulfite Siddiq et al. (1994) citric acid 1 0.25% ascorbic acid (in water) prior to packaging was very effective in limiting browning 10 mM inhibits 100% PPO, 1 mM AA inhibits 25% PPO, 1 mM l-cysteine inhibits 57% PPO Substrate is phenolics and chlorogenic acids authors indicated they should not be used interchangeably as sulfite alternatives without experimental verification of equivalence. O¨ zoglu and Bayindirli (2002), using the response surface methodology, found that the ascorbic acid, l-cysteine, and cinnamic acid combination provided better results as EB inhibitor than as individual compounds. The authors found 0.49 mM AA, 0.42 mM l-cysteine, and 0.05 mM cinnamic acid in cloudy apple juice inhibited browning for 2 h at 258C. 8.2.4.1. Honey The use of honey as a natural browning inhibitor was demonstrated in apple slices, grape juice, and model systems (Oszmianski and Lee, 1990). The browning of apple slices was inhibited to a greater extent by using 10% honey, than by a sucrose solution containing an equivalent sugar concentration. Analysis of honey revealed that a small peptide is responsible for the inhibition of polyphenol oxidase. The efficacy of honey in inhibiting polyphenol oxidase activity varied in accordance with the variety of honey (Chen et al., 1998).

8 . Inhibition and Control of Browning 195 8.2.4.2. Aromatic Carboxylic Acids Cinnamic acid and its analogs, p-coumaric, ferulic, and sinapic acids, were found to be potent inhibitors of apple polyphenol oxidases (Pifferi et al., 1974; Walker and Wilson, 1975). Cinnamic acid at levels of 0.01% was observed to be effective in providing long-term inhibition of polyphenol oxidase in apple juice (Walker, 1976). 8.2.4.3. Proteases Some plant proteases like ficin, papain, and bromelain are sulfydryl enzymes (Labuza et al., 1992; Taoukis et al., 1990), which are very effective as browning inhibitors. Pineapple juice was found to be effective in inhibiting browning in apple rings (Lozano-de-Gonzalez et al., 1993). Bromelain, organic acids, sulfydryl compounds, and certain metallic constituents of pineapple juice are believed to be responsible for this inhibitory effect. Polyphenol oxidase activity in plum juice was significantly reduced when the juice was treated in a column containing immobilized proteases (Arnold et al., 1992). 8.2.5. Miscellaneous Methods The market for lightly processed apples has increased rapidly (Schlimme, 1995). The develop- ment of retail and institutional precut apple products has been limited by browning, which can be controlled or minimized by using modified atmosphere packaging (MAP) with selected chemical treatments (El-Shimi, 1993). Lakakul et al. (1999) studied the use of plastic films to control moisture loss and respiration rate of cut apples. Raghavan et al. (1996) reported that damage to apple tissue texture could be reduced by calcium treatment and proper storage temperature. Figure 8.10 shows different treatments that have been experimented during the last few years to inhibit EB in fruit products. Although some of these methods have been impractical or expensive up to now, they are sufficiently innovative and safe for use in foods. Ultrafiltration and nanofiltration Sonication Supercritical irradiation CO2 Miscellaneous and non conventional EB treatments High Blanching pressure during size treatment reduction Figure 8.10. Miscellaneous and nonconventional methods for the treatment of enzymatic browning.

196 Fruit Manufacturing Zemel et al. (1990) showed that PPO activity could be irreversibly inhibited by tempor- arily lowering the pH to 2.0 with HCl. However, the pH must to be adjusted to its initial value by the addition of NaOH solution. This treatment inhibited EB and stabilized the apple juice, but was unfavorable as it affected the flavor. Tronc et al. (1997) used electrodialysis (ED) to prevent EB in cloudy apple juice, without employing additives, by temporarily acidifying the juice and then readjusting its pH to the initial value. ED is a membrane technique that results in the separation of ions (Lopez-Leiva, 1988). This method has been used to regenerate mineral acids and bases (Mani, l991). The applica- tion of ED with bipolar membranes proved to be a convincing approach for achieving changes in pH of cloudy apple juice. The authors indicated that in this way, the pH could be varied by the gradual incorporation of protons and hydroxyl ions derived from the dissociation of water, without affecting juice flavor by salt formation. Sapers et al. (1989) have shown that b-cyclodextrins inhibit browning of raw apple juice, and also found that ultrafiltration (UF) reduces EB in fruit products (Goodwin and Morris, 1991). Recent studies have shown that the simultaneous application of heat and ultrasonic waves had a synergistic effect on PPO inactivation. The process called mano-thermosonication needs special equipment and can be used with foods that are damaged by drastic heat treatment (Chen et al., 1992a,b). Supercritical carbon dioxide (SC-CO2) treatment was tried for inactivation of PPO in vegetables (Chen et al., 1992). In fruits SC-CO2 was used for the inactivation of pectinesterase (Arreola et al., 1991). With the exception of UF the other nonconventional methods involve heat treatment. 8.2.5.1. Irradiation Food irradiation is increasingly recognized as a method for reducing postharvest food losses and ensuring hygiene. Food irradiation is effective in securing the long-term preservation of foods through the inactivation of microorganisms. Fruits can be preserved by irradiation, thereby delaying their maturation or sprouting. Browning reduction in tropical fruits by gamma irradiation was reviewed by Thomas (1984, 1986). Browning was minimized by controlling the dosage level of the applied radi- ation. However, ionizing radiation at doses exceeding 1 kGy can introduce various types of physiological disorders in food products. Free radicals produced during the treatment of food with ionizing radiation, are capable of reacting with various food constituents and inducing undesirable side effects, such as tissue darkening, lipid oxidation, and decreased vitamin content. Nonenzymatic browning (NEB) reactions of free amino acids and proteins with reducing sugars, such as glucose, may be responsible for this discoloration. The sensitivity of enzymes to ionizing radiation is defined as the dose required to inactivate 63% of the original activity of the enzyme, D37. Table 8.6 lists D37 values of some enzymes in model systems measured in the dry state (Roozen and Pilnik, 1971). Combined treatments using both irradiation and heat or other methods have demon- strated a synergistic effect. 8.2.5.2. Ultrafiltration (UF) UF has shown to be effective in stabilizing the color of fruit juices (Flores et al., 1988; Sims et al., 1989). Moreover, Goodwin and Morris (1991) studied UF as an alternative to sulfiting for the control of EB. UF is believed to remove polyphenol oxidase, but not lower molecular

8 . Inhibition and Control of Browning 197 Table 8.6. Ionizing radiation doses to inactivate 63% (D37) of some selected enzymes. Enzyme D37 (kGy) Alkaline phosphatase 40 –50 Pectin esterase 60 Peroxidase 30 –70 weight polyphenols or Maillard-reaction precursors, which could undergo NEB during storage. Galeazzi et al. (1981) found that banana PPO fractions had molecular weights >30 kDa, within the range of molecular weight cut-offs for UF membranes. 8.2.5.3. High-pressure treatments High-pressure treatments reduce microbial counts and enzyme activity, and affect product functionality (Farr, 1990; Hoover et al., 1989; Cheftel, 1991). This provides a good basis for development of new processes for food preservation or product modifications (Mertens and Knorr, 1992). The first commercial products made, using high-pressure treatments, have been almost exclusively plants or product-containing plants (Knorr, 1995). Effects of high-pressure treatments on enzymes may be related to reversible or irreversible changes in protein structure (Cheftel, 1992). However, loss of catalytic activity can differ depending on type of enzyme, the nature of substrates, and the length and temperature of processing (Cheftel, 1992; Kunugi, 1992). Ogawa et al. (1990) reported the effect of high-pressure treatments on pectinesterase and peroxidase activity in model systems from mandarin juice. Cano et al. (1997) determined the effects of high-pressure treatments up to 400 MPa combined with mild heat treatments up to 6078C on different enzymes, including polyphenol oxidase (PPO) in strawberry pure´e and orange juice. Pressurization/depressurization treatments caused a significant loss of strawberry PPO (60%) up to 250 MPa. Although neither enzyme, including PPO, was completely inactivated after pressurization from 100 to 400 MPa, no recovery of enzyme activity was observed during storage. Degree of inactivation varied depending on the type of fruit and vegetable products studied (Knorr, 1995), and strong enzyme activation could be observed in cell-free extracts (Anese et al., 1995). Weemaes et al. (1998) found PPO from apples, avocados, grapes, pears, and plums was rather pressure stable. While inactivation of PPO from apple became noticeable at 600 MPa (258C), for pear PPO, pressures as high as 900 MPa were required (Fig. 8.11). Simultaneous application of mild heat increased the PPO inactivation rate constant. Table 8.7 lists some high-pressure treatments of fruit, which were positive for PPO inactivation. The inactivation of a pure enzyme by pressure is dependent on the immersion medium, the pH, as well as the temperature and duration of the treatment. Moreover, food constituents may show protective effects on enzymes during high-pressure treatment (Fig. 8.12). Mushroom polyphenol oxidase shows very high-pressure stability, although it is a thermosensitive enzyme that is readily inactivated by temperatures exceeding 508C (Weemaes et al., 1997). 8.3. INHIBITION AND CONTROL OF NONENZYMATIC BROWNING (NEB) The extent of NEB on fruit products depends on product composition, water activity, storage time, and temperature, as previously discussed (Chapter 7). NEB in fruit products may be

198 Fruit Manufacturing 0 −0.1 25؇C −0.2 Log relative activity −0.3 −0.4 −0.5 −0.6 −0.7 −0.8 Apple pear −0.9 −1 25 50 75 100 125 150 175 200 225 0 Time. min. Figure 8.11. Inactivation of PPO from apple and pear, at 800 and 900 MPa, respectively (adapted from Weemaes et al., 1998). inhibited or reduced by refrigeration, control of water activity in dehydrated fruits (Labuza and Saltmarch, 1981), reduction of amino nitrogen in juices (Pr´ıncipe and Lozano, 1991), and use of different chemical inhibitors. Two basic treatments have been used for the control or reduction of nonenzymatic reactions (Fig. 8.13): . Preventive methods, which are those that limit the advance of NEB reactions; while . Restorative methods, which basically let the NEB to develop, reducing later the product of the deteriorative reactions. 8.3.1. Preventive Methods 8.3.1.1. Temperature Control It is well known (Reynolds, 1965) that NEB reaction is retarded by reducing the temperature. Figure 8.14 shows a t–T plot of the several conditions apple juice undergoes from milling to distribution. In the particular case of processing apples to obtain juice concentrate, it may be expected that color, taste, and flavor would be undesirably modified and the questions are: Table 8.7. Effective high-pressure treatments for fruit PPO inactivation. Fruit Treatment Reference Apple (pH 4.5) >500 MPa/258C/1 min Anese et al. (1995) Avocado 800 MPa/258C Weemaes et al. (1998) Pear in slices 900 MPa/258C (slight inactivation) Weemaes et al. (1998) White grapes 700 MPa/258C Weemaes et al. (1998)

8 . Inhibition and Control of Browning 199 1 0.9 600 MPa 0.8 0.7 Activity (relative) 0.6 700 MPa 0.5 0.4 0.3 800 MPa 0.2 900 MPa 25 pH=7 45؇C 0.1 5 10 15 20 Time (min) 30 35 0 0 Figure 8.12. Effect of high hydrostatic pressure on relative activity of polyphenol oxidase at pH ¼ 7 (458C) (adapted from Seyderhelm et al., 1996). . How much, in any suitable unit, is the damage introduced by a particular operation? . Moreover, can it be quantitatively related to the magnitude of treatment, that magni- tude being also measured in any conventional units, such as temperature, time, con- centration, and the like? In the case of juices, more precisely apple juice concentrate, out of the those sensorial properties mentioned above, color is the one that can be submitted to a more objective measurement by well-known techniques. Flavor and taste, though perhaps more relevant from the hedonic point of view, are more subjective in nature. Preventive Temperature control Process optimization Ion exchange treatment Use of chemical inhibitors Neb treatment Restorative Synthetic adsorbers Nanofiltration Activated charcoal Figure 8.13. Basic nonenzymatic browning treatments.

200 Fruit Manufacturing 10000000 Transportation 1 month 1000000 30% 1 day 100000 Time (s) 10000 10% 1h Storage 1 min 1000 100 Clarification Evaporation 10 1 0 20 40 60 80 100 120 Temperature (؇C) Figure 8.14. Time–temperature plot during the processing of clarified apple juice concentrate (broken lines indicate percentage of color increase). Hence it is common to consider the browning expressed as the absorbance or optical density at a given light wavelength, namely 420 nm, when measured on the pure or single- strength juice. Less common, but still well known, is the qualification of the color through their three-tristimulus parameters (e.g., Hunter L, a, and b). 8.3.1.2. Process Optimization Concentration by evaporation is a very common practice in the fruit juice and pulp industry. Multiple-effect evaporators used in the fruit juice processing plants were designed to eliminate water under vacuum at relatively low temperatures. However, it is not unusual in practice to find very high temperatures in the first stage of processing. This can lead to changes both in color and flavor of the juice, mainly due to NEB. Process control has been increasingly adopted in the food industry during the last 30 years both to improve quality and reduce energy costs (Frost, 1977; Lozano et al., 1984). In order to properly adopt control strategies it is necessary to obtain either the empirical or the simulated dynamic model of the process by itself, without considering any control loop. Tonelli et al. (1990) presented a versatile computer package useful for the simulation of the open-loop dynamic response of a triple-effect evaporator for the concentration of fruit juice. In addition to fluid dynamics and thermal considerations some attention should be paid to the potential damage, which could be induced during concentration. However, selection of the pair values t–T to perform a given process is not a trivial task, but a trade-off between opposite considerations. For instance, low temperatures are more expensive because of the demand for a larger area, but high temperatures introduce the risk of scaling. Morgan (1967) showed that process side heat transfer coefficient dropped 10 times after 1 h operation in a tomato paste evapor- ator as a consequence of fouling. It is also known that heat transfer coefficient increases with the temperature difference between the heating medium and the solution, which makes advisable to work at high vacuums, low temperatures. But that means high vapor volumes, and larger piping and related pieces of equipment to maintain pressure drop within practical limits, which in turn means larger investment capital. If, alternatively, higher-pressure steam is used, the process is more expensive.

8 . Inhibition and Control of Browning 201 The formation of 5-hydroxy-methyl-2-furfuraldehyde (5-HMF), an intermediate of browning reactions in apple juice, has been directly related to the severity of heating in fruits and honey (Chapter 7). Toribio and Lozano (1986) found that this reaction follows a zero-order kinetics, after an induction period where no buildup of 5-HMF is detected. Babsky et al. (1986) also found that accumulation of 5-HMF achieves maximum accumulation after a long period of storage. These results may indicate that rate of formation of 5-HMF is similar that of a second-order autocatalytic reaction. However, no further advances were made to develop a complete and realistic mechanism of reaction based on the theory available. From an operational point of view and damage introduced by the thermal treatment, it is apparent that time is more critical than temperature: residence times of several minutes are common in evaporators for which relatively small changes in temperature may produce a dramatic increase in HMF concentration. Alternatively, if time can be kept within small values, the same temperature step does not provoke a significant HMF growth (Toribio and Lozano, 1986). This confirms the accepted practice of moving to lower time–higher tempera- ture combination whenever foods are to be thermally processed. It is experimentally known that actual residence times are several times longer than those calculated on the assumption of piston flow. For instance, in recirculating equipment, Moore and Pinkel (1968) showed that the actual holding time for 97% replacement of the liquid volume is 3.6 times greater than the average calculated as plug flow. There are, in addition, dead times in the distributors, pipes, pumps, and vapor separators, in which the juice is at the same temperature, which should be taken into account, as the damage is also in progress. However, this analysis is restricted to the liquid transit along the tubes since those times cannot be accurately estimated, and can be assumed to be the same in both configurations for comparison purposes. EXAMPLE 8.1 Application to multiple-effect evaporator design: evaporator selection Selection of a given type of evaporator is a task governed by many considerations. When fruit juice damage is considered, the falling film evaporator is an attractive alternative, since it imposes only short residence times to the solution, allowing for relatively low temperatures. Tonelli et al. (1990) simulated an actual 3-effect falling film unit, by means of a program specially formulated for that purpose, which provides mass flow rates and concentrations, at the entrance and discharge of each effect, as well as temperatures live steam consumption, and mass and enthalpy balances, for both backward and forward feed. It takes into account the rise in boiling point of solutions, and allows for feed preheating and vapor thermal recompression. The computer package simulates a triple- effect horizontal flash concentrator (Fig. 8.15), with a capability to concentrate about 7,600 kg/h of a 16.38Brix clarified apple juice (Table 8.8). A more complete description of the simulation model and the industrial unit was given previously (Tonelli et al., 1990). Once flow rates and temperatures were known, physical properties and Reynolds numbers in the tubes were easily computed. Film widths were calculated by means of the equation presented by Sideman (1981), at entrance, discharge, and arithmetic average. Holdup was calculated as a single value for average conditions. Finally, velocities and residence times were calculated for average conditions. All data are presented in Table 8.9.

202 Fruit Manufacturing Tap water Vapors Steam Barometric foot 1st effect Preheating Concentrate 2nd effect Feed 3rd effect Figure 8.15. Sketch of a triple-effect flash concentrator. By applying the correlation for damage as a function of time, temperature, and concen- tration to each effect for both backward and forward flow arrangements, the values of HMF formation shown in Table 8.8 are obtained. It is apparent that forwarded flow is much less harmful, the concentration being one order of magnitude lower than that produced in the countercurrent or backward arrangement. This is proof of the generalized practice in favor of the parallel flow for heat-sensitive materials. In both cases the first effect becomes the most damaging one, while in the counter- current one, the reduction in viscosity of the more concentrated product due to the higher temperature, is not enough as to reduce the residence time significantly, so the juice is submitted to the most unfavorable combination of the relevant variables. It is seen that while in the forward flow the first effect provokes 78% of the damage, in the backward one it is 99.3%, the absolute figure being ten times greater. Regarding the aroma-stripping operation the calculation on the commercial unit installed with the 3-effect evaporator did not indicate HMF formation for the prevailing conditions. Lozano et al. (1995) studied the open-loop dynamic response of an apple juice evapor- ator, based on the kinetics of 5-HMF formation. Results indicated that 5-HMF content of concentrated juice is strongly dependent on the temperature at the 1st effect. Level of 5-HMF was below 30 mg/L, a proposed reasonable limit (Toribio and Lozano, 1987) for clarified apple juice. Table 8.9 also lists the estimated increase in 5-HMF as affected by a variation in the temperature at the first effect of the simulated evaporator and with the set of industrial Table 8.8. Experimental industrial operating conditions. Feed flow rate (kg/h) 7650.0 Feed concentration (8Brix) 16.3 Feed temperature (8C) 45.0 Steam pressure (kPa) 182.0 Thirst effect pressure (kPa) 10.0

8 . Inhibition and Control of Browning 203 Table 8.9. Formation of 5-HMF as affected by temperature at the first effect. Temperature,8C Soluble solids,8C 5-HMF, mg/L 1st effect 3rd effect 100.1 60 5.02 104.4 60 7.80 109.1 60 12.63 100.1 70 6.6 104.4 70 10.8 109.2 71 16.8 100.0 75 7.4 105.1 75 12.5 109.1 75 18.6 operation conditions given in Table 8.8. The authors concluded that the knowledge of the dynamic response of heat-exchange equipment, like multiple-effect evaporators, together with the appropriate kinetics equations of deteriorative reactions is important to estimate and reduce the heat damage. This reduction can be achieved by the implementation of an appropriate control configuration. 8.3.1.3. Ion Exchange Treatment Ion exchange resins have been used in the industry for discoloration of syrups (Harris, 1986), the hydrolysis of lactose (Guerin and Lancrenon, 1982), and the anthocyanin recovery from fruit bagasses (Chiriboga and Francis, 1973) among other applications. Ion exchange treat- ments of liquid foods are legally permitted in several countries (Rankine, 1986; Johnson and Chandler, 1986). Ion exchange resins, as well as different types of adsorbers, have also been used in fruit juices (Withy et al., 1978) to elucidate the role of amino acids and polyphenols in the formation of brown color polymers (Cornwell and Wrolstad, 1981) and for deacidifica- tion and debittering (Johnson and Chandler, 1986). Pr´ıncipe and Lozano (1990) studied the effect of such treatments on the quality of the juices, as well as the operative applications of these processes. The exchange process is largely confined to a narrow region in the resin bed, which, within a short time after the liquid to be treated is flowing, moves down the bed at a constant rate and leaves the column at a point called the break through point. At that point the absorbed compound suddenly increases its concentration in the effluent, resulting in a typical S-curve. In order to calculate bed capacities the following equation can be used: ð Ve (8:1) Ct ¼ (X À X0)dV=Vra 0 where Ct is the total capacity of the column, Vra the average volume occupied by resin in the bed, X and X0 are the concentrations of compound to be absorbed in effluent and influent, respectively, V the volume eluted at any time, and Ve the volume at which exhaustion of column results. If integration takes place up to the breakthrough point (Vt) only, the resulting column capacity is called effective capacity. Figure 8.16 shows the reduction in the total amino acids (AA) when apple juice (158 Brix; pH ¼ 3:8) is passed through a cation exchange column (DOWEX 50 Â 8), as a function of the volume of effluent collected per gram of dry resin (Pr´ıncipe and Lozano, 1990).

204 Fruit Manufacturing 1.6 Amino acids, mg/100ml 0.9 3rd 0.2 2nd 1st Vt 50 100 150 Effluent, ml/g Figure 8.16. Effluent amino compound concentration versus effluent volume per gram of cation resin, with the number of column regenerations as a parameter. Vt is the volume at which break through point occurred (Reprinted from Lebens. Wiss. Technol., 24, Pr´ıncipe, L. and Lozano, J.E., Reduction and control of non-enzymatic browning in clarified apple juice by absorption and ion-exchange, pp. 34–38 (copyright) 1991, with permission from Elsevier). In general, successive regenerations did not reduce the column capacity and the resin may be used many times. Progress of the ion exchange may be monitored by pH readings in the outlet juice variable (Fig. 8.17). In order to recover the original juice pH, the cation- exchanged juice may be passed through an anion-exchange resin. The anion-exchange column also reduced the color of the juice. PH 4.0 3.0 Anion exchange 2.0 Cation exchange 20 40 60 80 100 Effluent, ml/g Figure 8.17. pH of column effluent as a function of effluent volume per gram of resin (Reprinted from Lebens. Wiss. Technol., 24, Pr´ıncipe, L. and Lozano, J.E., Reduction and control of non-enzymatic browning in clarified apple juice by absorption and ion-exchange, pp. 34–38 (copyright) 1991, with permission from Elsevier).

8 . Inhibition and Control of Browning 205 8.3.2. Restorative Methods During fruit juice discoloration, chromophoric components are eliminated, without modify- ing if possible, the other components of the product. While in the case of apple juice polyphenols are to be removed, red coloration in orange juice is caused by anthocyanins. The adsorption capacity of certain substances eliminating coloring matter by adsorption is exploited for discoloration. Properties such as grain size, surface area, and porosity define adsorbers’ capacity. This could be attributed to polyphenol adsorption. Adsorption forces are ruled by weak Van der Waals’ forces, which are temperature depen- dent. Adsorption of color is usually performed by adding activated carbon (AC) as a slurry to the juice, since this gave better dispersion than the addition of dry carbon. Table 8.10 lists the average characteristics of a typical AC used for apple juice discoloration (Pr´ıncipe and Lozano, 1990). The ACs listed in Table 8.10 had practically the same adsorption capacity and kinetics, which was in accordance with the similarity in their characteristics. Absorption of solutes from a dilute solution, as in the case of brown compounds in apple juice, can be described by an empirical isotherm similar to that attributed to Freundlich: Y ¼ m  Xn (8:2) where Y ¼ C=C0, color at the equilibrium/initial color; X is the units of color adsorbed (L juice/g AC), and m and n are constants experimentally determined. Discoloration is basically a batch operation where the amount of insoluble adsorbent (activated carbon) is very small with respect to the amount of product treated and the highly colored compounds removed are much more strongly adsorbed than the other juice constituents (sugars, acids, etc.). A solute, or color, balance is: A=J ¼ (Y0ÀYf )=(Xf ÀX0) (8:3) where A is the mass of activated carbon, J the volume of juice to be treated; X0 and Xf are the initial and final color adsorbed/mass of carbon, and Y0 and Yf are the initial and final color of the treated juice. Since the AC used ordinarily is fresh (X0 ¼ 0), substitution of (8.3) in (8.2) gives: A=J ¼ (Y0ÀYf )=(Yllm)l=n (8:4) This equation permits the calculation of the carbon to juice ratio, for a given change in the juice color from Y0 to Yf . Table 8.10. Properties of activated carbons. Appearance Black powder pH 4.5–5.5 Activity (blue methylene test) 20(minimum) Water content (%) 10 –15 Particle size (%): mesh 200 5 mesh 325 10 Density (apparent, kg/l) 0.34 – 0.38 Ash (%) 7 (maximum) Sulfates (%) 0.6 (maximum) Iron (ppm) 100

206 Fruit Manufacturing Example 8.2 Application of activated charcoal for apple juice discoloration Consider the need to reduce by 78% the color of a juice with activated charcoal. Adsorption of color by AC is fast and strongly dependent on the amount of AC used. On the other hand, the influence of temperature between acceptable working values (40 –808C) was practically negligible. The application of the Freundlich-type equation (8.2) to the equilibrium data resulted in: Y (C=C0) ¼ 44:38X 4:42(ÁC=gr:ÁC) (8:5) This equation was plotted in Fig. 8.18, which represents a typical equilibrium curve for a single-stage discoloration process. Figure 8.18 also shows the operating line between the initial relative color (Y0 ¼ 1) and the coordinates of point (Xl, Yl). If sufficient contact time is allowed and equilibrium is reached, the operating line intersects the Freundlich isotherm at Xl. The operating line in the example was a slope A=J ¼ 2:75, which directly determined the necessary amount of AC. 8.3.2.1. Effect of Storage Figure 8.19 shows the effect of prolonged storage on clarified apple juice color, after de- amino acid treatment. Sample ‘‘a’’ browned at approximately the same rate as the control juice, while ‘‘b’’ showed a reduced rate of browning. This behavior can be explained by considering that free amino acids remained in juice. Therefore, the heated juice had practically the same amino acid content as the fresh juice, which was demonstrated to directly enhance the rate of NEB (Babsky et al., 1986). 1.0 n = 4.52 .8 Y , C/Co .6 Operating line. slope = A/J .4 .2 (X1 , Y1) .1 .3 X , color / g c.a Figure 8.18. Nonenzymatic browning of apple juice concentrate as a function of time of storage, at 378C. Control: untreated juice. Sample ‘‘a’’: Fresh processed juice discolored with AC. Sample ‘‘b’’: Long-term storage, highly colored, AJC rediluted and treated with AC (Reprinted from Lebens. Wiss. Technol., 24, Pr´ıncipe, L. and Lozano, J.E., Reduction and control of non-enzymatic browning in clarified apple juice by absorption and ion-exchange, pp. 34–38 (copyright) 1991, with permission from Elsevier).

8 . Inhibition and Control of Browning 207 Red Del.: 75 BrixAbsorbance 420 Nm 1.8 37ЊC Sample “a” 1.4 1.0 o.6 Sample “b” o.2 0 40 80 120 Storage time, days Figure 8.19. Freundlich equilibrium curve for a single-stage discoloration of apple juice (Reprinted from Lebens. Wiss. Technol., 24, Pr´ıncipe, L. and Lozano, J.E., Reduction and control of non-enzymatic browning in clarified apple juice by absorption and ion-exchange, pp. 34–38 (copyright) 1991, with permission from Elsevier). On the other hand, in sample ‘‘b’’ most of the amino compounds, already reacted to form melanoidins, were adsorbed by the ACs, and NEB reactions scarcely developed. Figure 8.20 shows a typical browning curve during storage of apple juice with different levels of total amino acid content. RED DELICIOUSAbs., 420 nm 1.8 37ЊC Control 1.4 1.0 Sample “a” 0.6 Sample “b” 0.2 0 20 40 60 80 Time of storage, days Figure 8.20. Color of ion exchange-treated AC as a function of storage time, at 378C. Sample ‘‘a’’: Initial amino acid content, 57 mg/L. Sample ‘‘b’’: Initial amino acid control, 38 mg/l (Reprinted from Lebens. Wiss. Technol., 24, Pr´ıncipe, L. and Lozano, J.E., Reduction and control of non-enzymatic browning in clarified apple juice by absorption and ion-exchange, pp. 34–38 (copyright) 1991, with permission from Elsevier).

208 Fruit Manufacturing Table 8.11. Effect of ion-exchange treatment on apple juice. Before After Values determined in natural apple juice in natural Total amino acids (meq/l) 7.0 5.8 3 –30 Acidity (g/l) 3.7 4.5 2.4 –7.6 Malic acid, L (g/l) 4.1 4.0 Total phenols (ppm) 39.3 15.4 — Calcium (mg/100 g) 30.1 0.7 < 300 Sodium (mg/100 g) 23.s $0.1 Iron (ppm) 12.4 1.2 >3 Soluble solids (8Brix) 15.4 15.3 — Initial color (Abs4z($) 0.337 0.124 < 18 — < 0:5 *Babsky et al. (1986); Pr´ıncipe and Lozano (1991). Partially treated juice suffered some compositional changes, with the major components retaining acceptable values, but significant reductions in concentrations of calcium and iron were observed. Results of the experimental treatment of apple juice with ion-exchange resins are listed in Table 8.11. Calcium, amino acids, and other nutrients have been shown to affect the growth of microorganisms. Treated juices became much less susceptible to microbiological spoilage. On the other hand, Fe levels greater than 8 ppm are practically unacceptable in clarified apple juice. Adsorption, or ion exchange treatment, can modify the color attributes of the apple juice. Treated juices were more purple than fresh juice, and displayed a more natural chromaticity after several days of storage (Fig. 8.21). Pr´ıncipe and Lozano (1990) concluded that AC treatment should only be used to reduce the color of fruit juice concentrates subjected to prolonged and/or high temperature condi- tions of storage. Carbon adsorption of fresh juices will not reduce the rate of NEB. Yellow Orange Db 20 10 78 days Green 0 15 days 10 15 Da red –5 0 5 7 days –10 Purple –20 blue Figure 8.21. Hunter Da and Db parameters with time of storage at 378C. (&) Untreated juice, (O) AC-treated juice, (x) ion-exchange treated juice (Reprinted from Lebens. Wiss. Technol., 24, Pr´ıncipe, L. and Lozano, J.E., Reduction and control of non-enzymatic browning in clarified apple juice by absorption and ion-exchange, pp. 34–38 (copyright) 1991, with permission from Elsevier).

8 . Inhibition and Control of Browning 209 The process of discoloration with AC included tedious steps like clarification with bentonite and gelatin, filtration with a filterpress or vacuum filter, and reconcentration to original soluble solids’ content. On the other hand, fresh clarified fruit juice can be treated with cation þ anion exchange resins in order to reduce the amino compound content to levels low enough to satisfactorily reduce the rate of Maillard-type browning. Additionally, ion exchange treatment can also adjust the pH values and reduce the amount of micronutrients, which could make the juice more stable from a microbiological standpoint. AC and resins are readily available, and resins can be reactivated economically and simply, and used over and over again without significant working capacity reduction. 8.3.2.2. Use of PVPP (Polyvinyl Polypyrrolidone) The synthetic polymer polyvinyl polypyrrolidone (PVPP), which has been used in the bever- age industry since several years, is an absorbent, which shows selective affinity to polyphenols and tannins (Binnig, 1992). PVPP is used not only for discoloration of fruit juices, but also to prevent haze formation after processing. The regenerability of PVPP is the advantage of this product compared with the AC treatment. The application of PVPP can be realized either by batch process or with continuous dosage using a precoat filter for the elimination. For a significant discoloration as much as 3 g/L must be added (Hoffsommer and Cook, 1991). Regeneration of PVPP is done by alkaline solution followed by an acid neutralization. Polyvinyl polypyrrolidone (PVPP) shows a high selectivity for adsorption of polyphenols and has been established as a final stabilization treatment after UF (Gu¨ nther and Stocke´, 1995). 8.3.3. Miscellaneous Methods for Inhibition and Control of Nonenzymatic Browning 8.3.3.1. Color Reduction by Combined Methods Various pre- and post-treatments are available to avoid post-turbidity and discoloration of fruit juices. Stabilization of beverages by gelatin, bentonite, and silica gel is a widespread conven- tional treatment. Pretreatment techniques, including hyperoxidation of raw juice with PPO prior to UF, have been used as an alternative (Giovanelli and Ravasini, 1993; Maier et al., 1994). The use of combined adsorbent resins for clear apple juice stabilization has gained increasing importance as a final treatment after clarification (Schobinger et al., 1995; Weinand, 1995). However, such treatments imply an additional cost in existing juice processing lines. Polyphe- nols that are responsible for haze formation and browning during storage of clear apple juice and concentrate, could be selectively removed by an UF process using membranes of poly- ethersulfone and polyvinylpyrrolidone (Go¨ kmen et al., 1998). The authors compared their results with those from commercial UF membranes made out of regenerated cellulose acetate. The effects of laccase treatment on removal of polyphenols and color in apple juice were also investigated. Custom membranes were effective in reducing the amount of polyphenols. A remarkable desired color removal of apple juice could also be achieved using these membranes. Resulting products were stable in color and had clarity at 508C for up to 6 weeks. Laccase treatment increased the percentage removal of polyphenols from apple juices. However, laccase- treated samples were more susceptible to coloration and haze formation during storage. Kacem et al. (1987) studied the NEB during the storage of single-strength orange juice and synthetic orange drinks under aerobic and anaerobic conditions. The effect of free amino acids on browning was linear, with concentration being more pronounced in the presence of high

210 Fruit Manufacturing 0.7 0.6 4.2 mg/100mL 38 mg/100mL 0.5 71.8 mg/100mL 0.4 0.3 0.2 0.1 0 0 4 8 12 16 20 Figure 8.22. Effect of ascorbic acid concentration on browning of orange drinks with 0.66% amino acids. Solid line indicates juice stored in retort pouch, while dashed line represents juice stored in polyethylene pouch (Kacem et al., 1987 with permission). levels of ascorbic acid. Ascorbic acid was found to be the most reactive constituent of orange juice (Fig. 8.22). Packaging in polyethylene pouch greatly accelerates loss of ascorbic acid. 8.3.3.2. Use of Chemical Inhibitors Bolin and Steele (1987) investigated the effect of various treatments on NEB of dried apples, and determined that cysteine incorporation did not reduce browning during storage. The same was valid for manganese and tin addition. Many nonsulfite compounds have been shown to exhibit NEB protection in a variety of foods. Trehalose has been found to retard reaction between dry proteins and reducing sugars (Loomis et al., 1979). Bolin et al. (1976) used packaging with nitrogen headspace, to reduce the darkening rate in sulfured dried peaches. The authors attributed only 20% of the NEB to Maillard-type reactions. Tamaoka et al. (1991) studied the effect of high pressure (up to 500 MPa at 508C) on Maillard reaction between amino compounds with carbonyl compounds. Results indicate that the high pressure may suppress the browning process. 8.4. CONCLUSIONS The heating of the fruit mash or juice immediately after crushing the fruit appears to be the most effective way to control EB in many fruit products. The addition of sulfur dioxide, ascorbic acid, or cysteine has been used to retard browning during the heating period. The effect of a definite amount of AA in apple fruit pulp showed a very well-defined breaking point after which browning proceeds at the usual rate. Nontraditional methods, like UF of liquid fruit products, use of supercritical carbon dioxide, or sonication, in combination with heat treatments have been used by researchers since the last decade.

8 . Inhibition and Control of Browning 211 Although foreign additives are considered ever more undesirable in foods in general (for health reasons), the inhibition of chemicals will play primary role in the prevention of EB, at least in the very near future. The search for effective safe inhibitors of the NEB is stimulated by the need to: (1) prevent undesirable Maillard reactions, and (2) find alternatives to the use of sulfites. Organoleptic considerations are the major barrier to the use of some Maillard inhibitors (O’Brien and Labuza, 1994). Cysteine appears to be a good alternative to the use of sulfite in foods at present. REFERENCES Adams, J.B. (1991). Review, enzyme inactivation during heat processing of foodstuffs. Int. J. Food Sci. Technol. 26: 1–20. Anese, M., Nicoli, M.C., Dall Aglio, G. and Lerici, C.R. (1995). Effect of high pressure treatments on peroxidase and polyphenoloxiadse activities. J. Food Biochem. 18: 285–293. Arnold, J.F., Sinha, N.K. and Cash, J.N. (1992). Effect of immobilized proteases on polyphenol oxidase inhibition and associated degradation of anthocyanins in plum juice. Presented at Annual Meeting, Institute of Food Technologists, New Orleans, LA. Arreola, A.G., Balaban, M.O., Marshall, M.R., Peplow, A.J., Wei, C.I. and Cornell, J.A. (1991). Supercritical carbon dioxide effects on some quality attributes of single strength orange juice. J. Food Sci. 56: 1030–1033. Ashoor, S.H. and Zent, J.B. (1984). Maillard browning of common amino acids and sugars. J. Food Sci. 49: 1206 –1207. Babsky, N.E., Toribio, J.L. and Lozano, J.E. (1986). Influence of storage on the composition of clarified apple juice concentrate. J. Food Sci. 51(3): 564–567. Binnig, R. (1992). Light colour-stable cloudy apple juices. Fruit Process. 2: 133–136. Bolin, H.R. and Steele, R.J. (1987). Nonenzymatic browning in dried apples during storage. J. Food Sci. 52: 1654 –1657. Borestein, R. (1965). The comparative properties of ascorbic acid and erythorbic acid. Food Technol. 19: 1719. Cano, M.P., Marin, M.A. and Fuster, C. (1990). Freezing of banana slices. Influence of maturity level and thermal treatment prior to freezing. J. Food Sci. (USA) 55(4): 1070 –1072. Cheftel, J.C. (1991). Applications des hautes pressions en technologie alimentaire. Actualite’ des Industries alimen- taires et Agro-Alimentaires 108(3): 141–153. Cheftel, J.C. (1992). Effects of high hydrostatic pressure on food constituents: an overview. In High Pressure and Biotechnology, Balny, C., Hayashi, R., Heremans, K. and Masson, P. (eds.). Editions John Libbey Euro-text, Montrouge, pp. 195–209. Chen, J.S., Balaban, M.O., Wei, C.I., Marshall, M.R. and Hsu, W.Y. (1992a). Inactivation of polyphenol oxidase by high-pressure carbon dioxide. J. Agric. Food Chem. 40: 1233 –1236. Chen, J.S., Balaban, M.O., Wei, C.I., Marshall, M.R. and Hsu, W.Y. (1992b). Inactivation of polyphenol oxidase by high-pressure carbon dioxide. J. Agric. Food Chem. 40: 2345 –2349. Chen, L., Metha, A., Berenbaum, M. and Engeseth, N. (1998). The potential use of honey as an inhibitor of enzymatic browning. Presented at Annual Meeting, Institute of Food Technologists, Atlanta, GA. Chiriboga, C.D. and Francis, F.J. (1973). Ion exchange purified anthocyanin pigments as a colorant for cranberry juice cocktail. J. Food Sci. 38: 464 – 467. Chobot, R. and Horulaba, A. (1983). Stabilization of naturally cloudy apple juices by mechanical and heat treatment of must. Przemysl Spozywczy 37: 409– 411. Cornwell, C.J. and Wrolstad, R.E. (1981). Causes of browning in pear juice concentrate during storage. J. Food Sci. 46: 515–5l8. Dijkstra, L. and Walker, J.R.L. (1991). Enzymatic browning in apricots (Prunus armeniaca). J. Sci. Food Agric. 54: 229–234. Dimick, K.P., Ponting, J.D. and Makower, B. (1951). Heat inactivation of polyphenol oxidases in fruit pure´es. Food Technol. 6: 237–240. El-Shimi, N.M. (1993). Control of enzymatic browning in apple slices by using ascorbic acid under different conditions. Plant Foods Hum. Nutr. 43: 71–76. Farr, D. (1990). High pressure technology in the food industry. Trends Food Sci. Technol. 1: 14 –16.

212 Fruit Manufacturing Fennema, O.R. (1975). Preservation of food by storage at chilling temperatures. In Physical Principles of Food Preservation, Karel, M., Fennema, O.R. and Lund, D.B. (eds.). New York, Marcel Dekker, pp. 133–171. Finkle, B.J. and Nelson, R.F. (1963). Enzyme reactions with phenolic compounds: effect of o-methyl transferase on a natural substrate of fruit polyphenol oxidase. Nature 197: 902–905. Flores, J.H., Heatherbell, D.A., Hsu, J.C. and Watson, B.T. (1988). Ultrafiltration (UF) of white riesling juice: effect of oxidation and pre-UF juice treatment on flux, composition, and stability. Am. J. Enol. Vitic. 39: 180 –187. Frankos, V.H., Schmitt, D.F., Haws, L.C., McEvily, A.J., Iyengar, R., Miller, S.A., Munro, I.C., Clydesdale, F.M., Forbes, A.L. and Sauer, R.M. (1991). GRAS evaluation of 4-hexylresorcinol for use as a processing aid for prevention of melanosis in shrimp. Reg. Toxic Pharmacol. 14: 202–212. Frost, A.A. and Pearson, R.G. (1961). Kinetics and Mechanisms. John W. Wiley and Sons, New York. Frost, H.C. (1977). Role of computers in thermal food process control. Food Prod. Develop. 11(10): 11–17. Fukutani, K., Sano, K., Yamaguchi, T. and Ogana, H. (1986). Production of turbid apple juice and apple puree. Basic Patent JP 62259568 A2 871111. Galeazzi, M.A.M., Sgarbieri, V.C. and Costantinides, S.M. (1981). Isolation, purification and physicochemical characterization of polyphenol oxidase (PPO) from a dwarf variety of banana (Musa cavendishii L.). J. Food Sci.46: 150 –155. Genovese; D.B., Elustondo, M.P. and Lozano, J.E. (1997). Color and cloud stabilization by steam heating during crushing in cloudy apple juice. J. Food Sci. 62: 1171–1175. Gierschner, K. and Baumann, G. (1988). New method of producing stable cloudy fruit juices by the action of pectolytic enzymes. Ind. Obst-Gemuesev. 54: 217–218. Giovanelli, G. and Rasasini, G. (1993). Apple juice stabilization by combined enzyme membrane filtration process. Lebesm. Wiss. Technol. 26: 1–9. Go¨ kmen, V., Borneman, Z. and Nijhuis, H.H. (1998). Improved ultrafiltration for color reduction and stabilization of apple juice. J. Food Sci. 63(3): 504–507. Gola-Goldhirsh, A., Whitaker, J.R. and Kahn, V. (1984). Relation between structure of polyphenol oxidase and prevention of browning. Adv. Exp. Med. Biol. 1777: 43–51. Goodwin, C.O. and Morris, J. R. (1991). Am. J. Enol. Vitc. 42: 347–353. Goupy, P., Amiot, M.J., Duprat, F., Aubert, S. and Nicolas, J. (1995). Enzymatic browning of model solutions and apple phenolic extracts by apple polyphenoloxidase. J. Food Sci. 60(3): 497–501. Guerin, B. and Lancrenon, X. (1982). Ion exchange in the food industry. Modern Ind. Plants New Technol., 6: 379 –386. Gu¨ nther, S. and Stocke´, R. (1995). Scho¨ nen von Fruschtsa¨ften (6): Aktivkohle und PVPP. Flu¨ss. Obst. 62: 254. Halim, D.H. and Montgomery, M.W. (1978). Polyphenol oxidase of D’Anjou pears (Pyrus communis L.). J. Food Sci. 43: 603–608. Harris, E.W. (1986). Activated carbon in sugar refining. Ind. Eng. Chem. 34: 1057–1060. Hoffsommer, H.J. and Fisher-Ayloff-Cook, K.P. (1991). New technological aspects: decoloration and de-acidification of fruit juices. Fruit Process. 1(6): 99–101. Hoover, D.G., Metrick, C., Papineau, A.M., Farkas, D.F. and Knorr, D. (1989). Biological effects of high hydro- static pressure on food microorganisms. Food Technol. 43(3): 99–107. Janovitz-Klapp, A.H., Richard, F.C., Goupy, P.M. and Nicolas, J.J. (1990). Inhibition studies on apple polyphenol oxidase. J. Agric. Food Chem. 38: 926. Johnson, R.L. and Chandler, B.V. (1986). Reduction of bitterness and acidity in grapefruit juice by adsorptive processes. J. Sci. Food Agric. 33: 287–293. Kacem, B., Cornell, J.A., Marshall, M.R., Shiremen, R.B. and Matthews, R.F. (1987). Nonenzymatic browning in aseptically packed orange drinks: effect of ascorbic acid, amino acids and oxygen. J. Food Sci. 52(6): 1668– 1672. Kahn, V. (1985). Effect of proteins, protein hydrolysates and amino acids on o-dihydroxyphenolase activity of polyphenoloxidase of mushroom, avocado, and banana. J. Food Sci. 50(1): 111–115. Knorr, D. (1995). High pressure effects on plant derived products. In High Pressure Processing of Foods, Ledward, D.A., Johnston, D.E., Earnshaw, R.G. and Hasting, A.P.H. (eds.). Nottingham University Press, pp. 123–135. Kunugi, S. (1992). Effect of pressure on activity and specificity of some hydrolyticenzymes. In High Pressure and Biotechnology, Balny, C., Hayashi, R., Heremans, K. and Masson, P. (eds.). Editions John Libbey Euro–Tex, Montrouge, pp. 129–137. Labuza, T.P. and Saltmarch, M. (1981). The nonenzymatic browning reaction as affected by water in food. In Water Activity: Influences in Food Quality, Rockland, L.B. and Stewart, G.F. (eds.). Academic Press, London, UK, pp. 605–623.

8 . Inhibition and Control of Browning 213 Labuza, T.P. and Riboh, D. (1982). Theory and Application of Arrhenius kinetics to deterioration of foods. Food Technol. 36: 66–74. Labuza, T.P., Lillemo, J.H. and Taukis, P.S. (1990). Inhibition of polyphenol oxidase by proteolytic enzymes. Fruit Process. 2: 9–13. Lakakul, R., Beaudry, R.M. and Hernandez, R.J. (1999). Modeling respiration of apple slices in modified-atmosphere packages. J. Food Sci. 64: 105–110. Langdon, T.T. (1987). Prevention of browning in fresh prepared potatoes without the use of sulfiting agents. Food Technol. 41(5): 64 –67. Lee, C.Y., Smith, N.L. and Pennesi, A.P. (1983). Polyphenol oxidase from DeChaunac grapes. J. Sci. Food Agric. 34: 987–991. Loomis, S.H., O’Dell, S.J. and Crowe, J.H. (1979). Anhydrobiosis in nematodes: inhibition of the browning reaction of reducing sugars with dry protein. J. Exp. Zool. 208: 355–360. Lopez-Leiva, M. (1988). The use of electrodialysis in food processing. Part 1: Some theoretical concepts. Lebens. Wiss. Technol. 21: 119–125. Lozano, J.E., Elustondo, M.P. and Romagnoli, J.A. (1984). Control studies in an industrial apple juice evaporator. J. Food Sci. 49: 1422–1427. Lozano, J.E., Biscarri, R.D. and Ibarz, A. (1994). Enzymatic browning in apple pulps. J. Food Sci. 59: 1– 4. Lozano, J.E., Porras, J.A., Errazu, A. and Tonelli, S. (1995). Prediction of 5-HMF formation in an industrial apple juice evaporator. J. Food Sci. 60: 1292–1294. Lozano-de-Gonzalez, P.G, Barrett, D.M., Wrolstad, R.E., Durst, R.W. (1993). Enzymatic browning inhibited in fresh and dried apple rings by pineapple juice. J. Food Sci. 58(2): 399– 404. Luo, Y. and Barbosa-Ca´novas, G.V. (1996). Preservation of apple slices using ascorbic acid and 4-hexylresorcinol. Food Sci. Technol. Int. 2: 315. Maier, G., Frei, M., Wucherpfenning, K., Dietrich, H. and Ritter, G. (1994). Innovative processes for production of ultrafiltrated apple juices and concentrates. Fruit Process. 5: 134 –136. Mani, K.N. (1991). Electrodialysis water splitting technology. J. Membrane Sci. 58: 117–138. Mart´ınez, J.H., Solano, F., Penadiel, R., Galindo, J.D., Iborra, J.L. and Lozano, J.A. (1986). Comparative study of tyrosinase from different sources: relationship between halide inhibition and the enzyme active site. Comp. Biochem. Physiol. 83B: 633. Matsui, S., Ito, S. and Murata, N. (1957). Studies on apple juice processing. 1: Prevention of oxidative darkening in apple juice during processing. Tokai Kinki Nosikenkyu Hokoku 4: 1–18. McEvily, A.J., Iyengar, R. and Otwell, W.S. (1992). Inhibition of enzymatic browning in foods and beverages. Crit. Rev. Food Sci. Nutr. 32: 253–273. McKenzie, D.L. and Beveridge, T. (1988). The effect of storage, processing and enzyme treatment on the micro- structure of cloudy Spartan apple juice particulate. Food Microstruct. 7: 195–203. Mertens, B. and Knorr, D. (1992). Development of nonthermal processes for food preservation. Food Technol. 46(5): 124 –133. Molnar-Perl and Friedman, M. (1990). Inhibition of browning by sulfur amino acids, apples and potatoes. J Agric. Food Chem. 38(8): 1652–1656. Montgomery, M.W. (1983). Cysteine as an inhibitor of browning in pear juice concentrate. J. Food Sci. 48: 951–952. Montgomery, M.W. and Petropakis, H.J. (1980). Inactivation of Bartlett pear polyphenol oxidase with heat in the presence of ascorbic acid. J. Food Sci. 45: 1090 –1091. Moore, J.K. and Pinkel, E.B. (1968). When to use single pass evaporators. Chem. Eng. Prog. 64(7): 39–44. Morgan, A.I. (1967). Evaporation concepts and evaporators design. Food Technol. 21: 1353–1359. O’Brien, J.M., Labuza, T.P. (1994). Symposium provides new insights into nonenzymatic browning reactions. Food Technol. 48(7): 56 –58. Ogawa, H., Fukuhisa, K., Kubo, Y. and Fukumoto, H. (1990). Pressure inactivation of yeast, molds and pectines- terase in Satsuma mandarin juice, effect of juice concentration, pH and organic acids and comparison with heat sanitation. Agric. Biol. Chem. 54(5): 1219–1225. Oszmianski, J. and Lee, C.Y. (1990). Inhibition of polyphenol oxidase activity and browning by honey. J. Agric. Food Chem. 38: 1892–1898. O¨ zoglu, H. and Bayindirli, A. (2002), Inhibition of enzymic browning in cloudy apple juice with selected antibrown- ing agents. Food Control 13(4 –5): 213–221. Park, E.Y. and Luh, B.S. (1985). Polyphenoloxidase of kiwifruit. J. Food Sci. 50: 678–683. Pierpoint, W.S. (1966). The enzymatic oxidation of chlorogenic acid and some reactions of the quinone produced. Biochem. J. 98: 567.

214 Fruit Manufacturing Pifferi, P.G., Baldassari, L. and Cultrera, R. (1974). Inhibition by carboxylic acids of an o-diphenol oxidase from Prunus avium fruit. J. Sci. Food Agric. 25: 263–270. Pr´ıncipe, L. and Lozano, J.E. (1991). Reduction and control of non-enzymatic browning in clarified apple juice by absorption and ion-exchange. Lebens. Wiss. Technol. 24: 34 –38. Raghavan, G.S.V., Alvo, P., Garie´pi, Y. and Vigneault, C. (1996). Refrigerated and Controlled Modified Atmosphere Storage. in Processing Fruits: Science and Technology. 1. Biology, Principles, and Applications, Somogyi, L.P., Ramaswamy, H.S. and Hui, Y.H. (eds.). Technomics Publishing Company, Inc., Lancaster, USA, pp. 135 –167. Rankine, B. (1986). Using ion-exchange to alter acidity. Aust. Grapegrower Winemaker 22, 9–10. Reynolds, T.H. (1965). Chemistry of nonenzymatic browning—II. Food Res. 14: 167–175. Roozen, J.P. and Pilnik, W. (1971). On the stability of adsorbed in water deficient systems. V. The effect of storage irradiation by electrons on the stability of alkaline phosphatase, Lebens. Wiss. Technol. 4: 196–200. Sapers, G.M. (1991). Control of enzymatic browning in raw fruit juice by filtration and centrifugation. J. Food. Proc. Preserv. 15: 443–456. Sapers, G.M. and Douglas, F.W. (1987). Uptake and fate of ascorbic acid-2-phosphate in infiltrated fruit and vegetable tissue. Measurement of enzymatic browning at cut surfaces and in juice of raw apple and pear fruits. J. Food Sci. 52: 1258–1262. Sapers, G.M. and Ziolkowski, M.A. (1987). Comparison of erythorbic and ascorbic acid as inhibitors of enzymatic browning in apples. J. Food Sci. 52: 1732–1737. Sapers, G.M., El-Atawy, Y.A., Hicks, K.B. and Garzarella, L. (1989). Effect of emulsifying agents on inhibition of enzymatic browning in apple juice by ascorbyl palmitate, laurate and decanoate. J. Food Sci. 54: 1096. Sapers, G.M., Miller, R.L., Douglas, F.W. and Hicks, K.B. (1991). Uptake and fate of ascorbic acid-2-phosphate in infiltrated fruit and vegetable tissue. J. Food Sci. 56: 419. Schlimme, D.V. (1995). Marketing lightly processed fruits and vegetables. HortScience 30: 15–17. Schobinger, U., Barbic, I., Durr, P. and Waldvogel, R. (1995). Phenolic compounds in apple juice. Positive and negative effects. Fruit Process. 6: 171–174. Seib, P.A. and Liao, M.L. (1987). Ascorbate-2-phosphate esters and method of making the same. US Patent 4,647,672. Seyderhelm, I., Boguslawski, S., Michaels, G. and Knorr, D. (1996). Pressure induced inactivation of selected food enzymes. J. Food Sci. 61: 308–310. Shannon, C.T. and Pratt, D.E. (1967). Apple polyphenol oxidase activity in relation to various phenolic compounds. J. Food Sci. 32: 479– 483. Siddiq, M., Arnold, J.F., Sinha, N.K and Cash, J.N. (1994). Effect of polyphenol oxidase and its inhibitors on anthocyanin changes in plum juice. J. Food Proc. Preserv. 18: 75–84. Sideman, S. (1981). Film evaporation and condensation in desalination. In Heat Exchangers: Thermal-hydraulic fundamentals and design, Kakac et al. (eds.). Hemisphere Publishing Company, p. 357. Sims, C.A., Johnson, R.P. and Bates, R.P. (1989). Quality of a non-sulfited vitis rotundifolia and a Euvitis hybrid white wine produced from ultrafiltered juice. Am. J. Enol. Vitic. 40: 272–276. Tamaoka, M., Itoh, N. and Hayashi, R. (1991). High pressure effect on Maillard reaction. Agric. Biol. Chem. 55: 2071–2074. Taoukis, P.S., Labuza, T.P., Lillemo, J.H. and Lin, S.W. (1990). Inhibition of shrimp melanosis (black spot) by ficin. Lebens. Wiss. Technol. 23: 52–54. Thomas, P. (1984). Radiation preservation of food of plant origin. Part 1. Potatoes and other tuber crops. Crit. Rev. Food Sci. Nutr. 19: 327–379. Thomas, P. (1986). Radiation preservation of food of plant origin. Part 3. Tropical fruits: bananas, mangoes, and papayas. Crit. Rev. Food Sci. Nutr. 23: 147–205. Tonelli, S., Romagnoli, J.A. and Porras, J.A. (1990). Computer package for transit analysis of industrial multiple- effect evaporators. J. Food. Eng. 12: 267–281. Toribio, J.L. and Lozano, J.E. (1986). Heat induced Browning of clarified apple juice at high temperatures. J. Food Sci. 51(1): 172–177. Toribio, J. and Lozano, J. (1987). Formation of 5-HMF in clarified apple juice during heating at elevated temper- atures. Lebens. Wiss. Technol. 20: 59–63. Tronc, J.S., Lamarche, F. and Makhlouf, J. (1997). Enzymatic Browning inhibition in cloudy apple juice by electrodialysis. J. Food Sci. 62: 75–78. Va´mos-Vigya´zo´ , L. (1995). Prevention of enzymatic browning in fruits and vegetables. In Enzymatic Browning and its Prevention, Lee, C.Y. and Withaker, J.R. (eds.). ACS Symposium Series 600, American Chemical Society, Washington, DC.

8 . Inhibition and Control of Browning 215 Walker, J.R.L. (1976). The control of enzymatic browning in fruit juices by cinnamic acids, J. Food Technol. 11: 341–345. Walker, J.R.L. and Wilson, E.L. (1975). Studies on the enzymatic browning of apples. Inhibition of apple o-diphenol oxidase by phenolic acids. J. Sci. Food Agric. 26: 1825–1831. Weemaes, C., Rubens, P., de Cordt, S., Ludikhuyze, L., Van Den Broeck, I., Hendrickx, M., Heremans, K. and Tobback, P. (1997). Temperature sensitivity and pressure resistance of mushroom polyphenoloxidase. J. Food Sci. 62: 261–266. Weemaes, C., Ludikhuyze, L., Van der Broeck, I. and Hendrickx, M. (1998). High pressure inactivation of poly- phenoloxidases. J. Food Sci. 63: 873–877. Weinand, R. (1995). Adsorbent resins in the beverage industry. Fruit Process. 6: 166. Weller, A., Sims, C.A., Matthews, R.F., Bates, R.P. and Brecht, J.K. (1997). Browning susceptibility and changes in composition during storage of carambola slices. J. Food Sci. 62(2): 256 –260. Withy, L.M., Heatherbell, D.A. and Strachan, G. (1978). The chemical composition of some New Zealand apples and their juices. NZ J. Sci. 21: 91–97. Yemeniciog¨ılu, A., Ozkan, M. and Cemerog¨ılu, B. (1997). Heat inactivation kinetics of apple polyphenoloxidase and activation of its latent form. J. Food Sci. 62(3): 508–510. Zemel, G.P., Sims, C.A., Marshall, M.R. and Balaban, M. (1990). Low pH inactivation of polyphenoloxidase in apple. J. Food Sci. 55: 562–565.

INDEX A Apple juice (cont.) storage-related loss of, 153, 154 Absorbance spectrophotometry, 99–104 Acetic acid, as preservative, 8 browning in, 162, 204 Acetoin, 153 canned, 24 N-Acetyl-L-cysteine, as browning inhibitor, 192 clarification of, 35–37 Acidity, 157 clarified measurement of, 7 boiling point rise in, 94, 95 ripening-related decrease in, 21 comparison with cloudy apple juice, 110 as taste component, 136 concentration of, 198–200 Activated carbon, use in browning control, 203–207 effect of storage on, 204–207 Activity coefficients, of aroma components, 5-hydroxymethylfurfural in, 175, 176 118–125 thermophysical properties of, 93–95 experimental values, 124, 125 cloudy, 109 NRTL model, 121, 122 browning inhibition in, 186, 194 UNIFAC model, 121, 123 comparison with clarified apple juice, 110 UNIQUAC model, 121–123 pH of, 194 Wilson equation, 121, 122 starch granules in, 40, 41 Agglomeration, 67–71 viscosity of, 116–119 selective (spherical), 71 color difference development in, 186 Air, chemical composition of, 12, 13 concentration of, 36 Aligning, as fruit sorting method, 29 density of, 93, 94 Alkaline phosphatase, radiation-related inactivation of, enzymatic browning in, 193 195 enzymatic browning inhibition in, 188–192 Aluminum cans, 6 enzymatic processing of, 36–38 Amino acids, 136. See also names of specific amino acids frozen, 24 in browning, 164, 165, 199, 200 nonenzymatic browning in 5-hydroxymethylfurfural in, 173, 175–178 effect of ascorbic acid on, 207, 208 kinetics of, 169–171 in fruit juice, storage-related loss of, 153–155 Maillard-type reactions in, 167 g-Aminobutyric acid, 153, 170 storage-related, 204–207 Amylase, 40 nonenzymatic browning inhibition in, 196–198 Amyloglucosidase, 35 with activated carbon, 203–205 AnalySIS 2.1, 113 with ion-exchange resins, 201, 202, 205–207 Anions, as browning inhibitors, 187, 189 organic acid content of, 157 Anthocyanidins, 149, 150 pasteurization of, 56 Anthocyanins, 99, 148, 149, 157 pH of, 35, 40 recovery from fruit bagasses, 199 effect of ion exchange on, 202 storage-related loss of, 158 reducing sugars in, 156 Anthoxanthins, 148 specific heat of, 81 Antibrowning agents, 187–193 starch content of, 40, 41 nonconventional, 187, 191–193 sucrose hydrolysis in, 156 Antoine equation, 95, 121 sugar content of, as natural preservative, 36 Appearance, as food quality indicator, 99, 161 viscosity of, 91, 92 Apple butter, pH of, 138 Apple juice concentrate, nonenzymatic browning in, 171, Apple juice 172 amino acid content of, 153 Apple pulp enzymatic browning inhibition in, 192 as browning cause, 204 217

218 Index Apple pulp (cont.) Arginine, 135, 136, 170 enzymatic processing of, 36, 37 L-Arginine, 153 light-colored, 165 Aroma Apples formation during ripening, 21 aroma/aroma components of, 119, 146, 147 properties of, 123 browning in, 99 Aroma compounds, 144, 146, 147 bulk density of, 78 activity coefficients of, 118–125 canned, 22 chemical composition of, 134, 135 experimental values, 124, 125 cooling methods for, 12 NRTL model, 121, 122 dried, 22, 23 UNIFAC model, 121, 123 enzymatic browning in, 162 UNIQUAC model, 121–123 inhibition of, 192, 195, 196 Wilson equation, 121, 122 luminosity in, 165 effect of storage on, 152, 153 measurement of, 164, 165 volatile, 119–120 in unripe fruit, 164, 165 infinite dilution coefficients of, 120, 121 frozen, 22 relative volativity of, 119 harvest time for, 157 vapor pressure of, 121 lightly processed, 193 Aroma stripping and recovery, 26, 35, 119–125, 146 major commercial applications of, 4 by flash condensation, 124–126 milling processing of, 30, 31 Arrhenius relationship, 183, 184 pectin content of, 140 Ascorbic acid pH of, 138 in browning, 162, 206, 207 pigment content of, 134 Maillard reactions in, 171 polyphenol oxidase content of as browning inhibitor, 187–192 heat-inactivation kinetics of, 183 fruit content of, 144, 145 substrates for, 163 processing and storage-related destruction of, 150–152 protein content of, 136 vegetable content of, 144 red skin color of, 157 Ascorbic acid derivatives, as browning inhibitors, 192 scientific name of, 4 Ascorbic acid-6-fatty acid esters, as browning inhibitors, specific heat of, 81 188, 189 starch content of, 35, 139 Ascorbic acid-2-phosphate esters, as browning starch granules, 139, 140 inhibitors, 188, 189 storage life of, 12 Ascorbic acid-2-triphosphate esters, as browning storage temperature for, 9, 157 inhibitors, 188, 189 unripe, starch content of, 35 Ascorbyl fatty acid esters, as browning inhibitors, washing of, 27 188–189 water content of, 134 Ascorbyl-6-fatty acid esters, as browning inhibitors, 192 world production of, 2, 4 Ascorbyl phosphate esters, as browning inhibitors, 188 Asparagine, 153–155, 170 Apple sauce, 22 Aspartic acid, 153, 154 pH of, 138 Aspergillus niger, 38 specific heat of, 81 Atomization, in spray drying, 65 viscosity of, 93 Avocados enzymatic browning inhibition in, 192, 195, 196 Apricot products, enzymatic browning inhibition in, 186 fat content of, 140 Apricots major commercial applications of, 4 polyphenol oxidase phenolic substrates in, 163 dried, 22 protein content of, 136 frozen, 22 scientific name of, 4 major commercial applications of, 4 storage temperature for, 186–176 pectin content of, 140 world production of, 4 pH of, 138 polyphenol oxidase phenolic substrates in, 163 B protein content of, 136 scientific name of, 4 Bag filters, for powder recovery, 65, 66 world production of, 4 Bananas Arabanase, 37, 38 Arabans, 40 browning in, 162 Arabinose, 139

Index 219 Bananas (cont.) C chemical composition of, 135 enzymatic browning inhibition in, 192, 195 Caffeic acid, 148 esters content of, 144, 146 Cage presses, 32, 33 major commercial applications of, 4 Calcium polyphenol oxidase content of heat-inactivation kinetics of, 183 as apple preservative, 193 phenolic substrates of, 163 fruit content of, 140, 141 protein content of, 136 Calcium chloride treatment, of harvested scientific name of, 4 fruits, 7, 8 specific heat of, 81 Calorimetry, differential scanning, 80 starch content of, 139 Candy, 3 storage temperature for, 186–176 Canned fruits, 21, 22 world production of, 2, 4 Carambola juice, sugar content of, 139 Carambolas Basic Four food guide, 6 enzymatic browning inhibition in, 192 Beans, protein content of, 136 oxalic acid content of, 137 Beer-Lambert law, 101 protein content of, 136 Beer’s law, 100–102 starch content of, 139 Belt conveyors, 29 Caramel, 150 Bentonite Caramelization, in nonenzymatic browning, 165–167 as browning inhibitor, 207 Carbohydrates. See also Sugars as clarification agent, 35, 36 fruit content of, 134, 135, 137–140 Benzaldehyde, flash condensation recovery of, 126 production and function of, 137, 138 Benzoic acid, as browning inhibitor, 164 Carbon dioxide Berries diffusion through packaging film, 14–17 frozen, 22 effect on plant respiration, 13 refrigeration of, 186 in fruit storage facilities, 14 Beta-carotene, 135 in modified atmosphere packaging, 15 Binder media, in agglomeration, 68, 70 supercritical, 194 Bin food driers, 63 Carbon dioxide processing, 56 Bins, use in food processing, 27 b-Carotene, 148 Birdseye, Charles, 6 Carotenoids, 135, 147–148 Blackberries, 4 degradation of, 157 Blanching, as enzymatic browning control Catechins, 148–150, 163, 164 method, 182, 183 Catecholase. See Polyphenol oxidase Blueberries Cellars/caves, as fruit storage areas, 11 cooling methods for, 12 Cellulases, 37 pectin content of, 140 Cellulose, 21, 78, 135, 137, 138 storage life of, 12 Centrifugation Boiling point rise, 94, 95 as enzymatic browning control Boysenberries, 4 Bread, protein content of, 136 method, 185 Breadfruit, 4 as extraction process, 34 Brix-to-acid ratio, 7 Cereals, protein content of, 136 Bromelain, as browning inhibitor, 187, 193 Champagne, 3 Brown extractors, 30 Chelating agents, as browning inhibitors, 187 Browning Chemical composition, of as deterioration cause, 161–179 fruits and fruit products, 133–160 enzymatic. See Enzymatic browning amino acids, 136 inhibition and control of, 181–212 carbohydrates, 137–140 nonenzymatic. See Nonenzymatic browning effects of processing or storage on, 150–158 reducing sugars in, 156 organic acids, 136, 137 Bruising, in harvested fruits, 7 pectin, 140 Butanol, as aroma component, 125 proteins, 136 flash condensation recovery of, 126 proximate, 133–150 Butyl acetate, as aroma component, 124 starch, 138–140 flash condensation recovery of, 126 Chemical peeling, 29

220 Index Chemical preservatives, See also names of specific Color, of fruits and fruit products. See also Browning; preservatives 7,8 Pigments (cont.) definition of, 7, 8 attributes of, 106 for semiprocessed fruit products, 17, 18 effect of processing and storage on, 147 measurement of, 7, 99–108 Chemical treatment, of harvested fruits, 7, 8 absorbance spectrophotometry-based, 99–104 Cherries tristimulus colorimetry-based, 99–104 visual systems-based, 100 frozen, 22 relationship to pigment concentration, 108 major commercial applications of, 4 mineral content of, 141 Color compounds. See Pigments pectin content of, 140 Colorimeters/colorimetry pH of, 138 protein content of, 136 applications of, 108 scientific name of, 4 definition of, 102 world production of, 4 tristimulus, 99, 104–108 Chill injury, 186, 187 Chitosan, as browning inhibitor, 187, 192 CIELAB method, 106–108 Chlorophyll, 147 Commission Internationale de L’Eclerage (CIE) breakdown during ripening, 21 CIELAB method, for surface color quantification, system, 106–108 106–108 Compaction, as size enlargement process, 67 Cinnamate, as browning inhibitor, 189, 192 Concentration, of fruit juices, 26, 35–36 Cinnamic acid, as browning inhibitor, 164, 192 through evaporation, 175, 198 Cinnamic acid esters, as polyphenol oxidase effect of boiling point rise on, 94, 95 substrates, 163, 164 Citric acid, 21, 136, 157 Concentrators, triple-effect, 198–201 as browning inhibitor, 192 Condensation, formation on stored fruit, 8 in peaches, 171 Conduction, 74, 75 as preservative, 8 Citronellon, 153 Laplace equation of, 83 Citrus fruit. See also Lemons; Limes; Oranges Continuous belt presses, 32, 33 aroma components of, 118, 119 Continuous pressure filters, 42 Citrus juice. See also Lemon juice; Orange juice Convection, 74, 75 nonenzymatic browning in, 167 Cooling, of harvested fruits, 8–12 Citrus juice extractors, 30 Clarification processes, 26, 35, 36 methods, 9–12 centrifugation, 35 alternative methods, 11 concentration, 26, 35 forced-air cooling, 9, 10, 12 of partial concentrates, 35, 36 hydrocooling, 9–12 temperature for, 40 package icing, 9 Clausius-Clapeytron equation, 95 room cooling, 9, 10, 12 Clostridium botulinum, 13 top icing, 9, 11 Coagulation, 109 vacuum cooling, 9 Coconuts, 4 Cold wall forced-air cooling, 10 purpose of, 9 Colloidal particles Copper, 141, 144, 152, 157 as fruit juice viscosity cause, 115–118 Coring, of harvested fruit, 29 size, shape, and distribution measurement of Coumaric acid, 148 p-Coumaric acid, as browning inhibitor, 164, 192 with electron microscopy, 112, 115 Crab apples, 4 with photon correlation, 115 with sedimentation methods, 113, 114 pectin content of, 140 Colloidal stability, 109, 111 Cranberries, 4 DVLO theory of, 111 Colloidal systems, types of, 110 pectin content of, 140 Colloids, 109 Cranberry sauce, 22 Color, of fruits and fruit products, 161. See also Cream of tartar (potassium hydrogen Browning; Pigments tartrate), 137 Cucumbers, pH of, 138 Currants, 4 pectin content of, 140 pH of, 138 Cutting, of harvested fruit, 29 b-Cyclodextrans, as browning inhibitors, 194 Cyclodextrin, as browning inhibitor, 187 Cyclone collectors, for powder recovery, 65, 66

Index 221 Cysteine, as browning inhibitor, 187, 189, 192 Dodecanal, 153 Cystine, 136 Dried fruits, 21, 23 Dried products, definition of, 62 D Drying, as preservation method Deacidification, 199, 200 dehydration-related shrinkage during, 125–128 Debittering, 199, 200 historical development of, 3 Debye length, 111 Deep freezing, invention of, 6 E Dehydrated products, definition of, 62 Dehydration, as fruit processing Eggplants, polyphenol oxidase phenolic substrates in, 163 method, 62–67 critical moisture content (Xcr) in, 63 Egyptians, 3 definition of, 62 Elderberries, 4 driers for, 63–67 Electrodialysis, as enzymatic browning inhibition belt, 64 method, 194 bin, 63 Electromagnetic waves, 73, 74, 100 cabinet, 64 Electron microscopy, of colloidal particles, 112, 113, 115 continuous belt or conveyor, 64 Electrostatic (charge) repulsion, in food dispersions, 111 drum, 64 Electrostatic forces, 69 explosion puffing, 65 Encapsulation, as size enlargement process, 67 fluidized bed, 63, 65 Endocarp, 1, 2 microwave, 65 Enthalpy, 73, 74, 80 osmotic bed, 65 Enzymatic browning, 161–165 spray, 62, 65–67 sun or solar, 64 effect of temperature on, 165 three-stage, 67 inhibition and control of, 163, 181–195 tunnel, 64 two-stage, 67 with chemical treatments, 183, 187–190 vibrofluidizers, 63 with color measurement, 163–165 drying curve in, 63 with miscellaneous methods, 193–195 fruit shrinkage during, 125–128 with nonconventional chemical treatments, 183, shrinkage coefficient, 127, 128 Dehydroascorbic acid, in browning, 162 191–193 Dehydroascorbic acid (DHAA), 165 with thermal treatments, 182–187 Density, 73, 74, 77–79 kinetics of, 163–165 bulk, 77–79 phenolic compounds and oxidases in, 161–163 definition of, 77 susceptibility to, 162 of fruit juice, 93, 94 Enzymes. See also specific enzymes measurement of, 77–79 apple content of, 134 particle, 77 in fruit and fruit juice processing, 36–41 substance, 77 inactivation of Depectinization, 35, 36, 40 Arrhenius relationship in, 183, 184 Destarching, of fruit juices, 36 with chemical agents, 183, 187–190 Deterioration, of fruits and fruit products for enzymatic browning control, 182–187 browning-related, 161–179 with miscellaneous methods, 193–195 color measurement of, 99 with refrigeration, 186, 187 mechanisms of, 161, 162 with thermal methods, 182–187 postharvest, 6, 7 Erythorbic acid, as browning inhibitor, 188, 190–192 DHAA (dehydroascorbic acid), 165 Essential amino acids, 136 Diffusion, as extraction process, 34 Essential oils, in apples, 134 Dihydroquercetin, 163 Esters, 144, 146 3,4-Dihydroxy phenylalanine, as polyphenol oxidase Ethanol, as aroma component, 125 substrate, 163, 164 flash condensation recovery of, 126 Diphenols, transformation to melanins, 164 Ethyl acetate, as aroma component, 124 Dispersibility, 68 flash condensation recovery of, 126 Dispersions. See Food dispersions Ethyl butyrate, as aroma component, 124, 153 flash condensation recovery of, 126 Ethylene, 13, 21 Ethylenediamine tetraacetic acid (EDTA), as browning inhibitor, 187, 189

222 Index Ethyl valerate, as aroma component, 124 Filtration methods and filters (cont.) flash condensation recovery of, 126 filter press (plate and frame), 43 vacuum filters, 45 Evaporated products, definition of, 62 vertical and horizontal pressure leaf, 43, 44 Evaporation, 58–62 Fining, 26, 35, 36 as concentration method, 175, 198 Fining agents, 35 effect of boiling point rise on, 94, 95 Flavan, 148 Flavones, 148, 149 condensers for, 58 Flavonoids, 162 definition of, 58 Flavonols, 148, 149 heat exchangers for, 58–60 Flocculating agents, 35 vacuum system for, 58 Flocculation, 109 vapor separator for, 58–60 FMC citrus juice extractors, 30 Evaporators, 58–62 Folic acid, vegetable content of, 144 batch pan (calandria), 58, 59 Folin-Ciocalteau reagent, 157 falling film, 60 Food dispersions, 109–118 multiple-effects, 61, 62, 198–200 characterization of, 111, 112 with aroma recovery, 124–126 Debye length in, 111 mechanical vapor recompression, 61, 62 definitions of, 109–111 thermocompression, 61, 62 electrostatic (charge) repulsion in, 111 rising film, 59 particle size, shape, and size distribution in, 112–114 scraped-surface, 60, 61 stability of, 109, 111 Exocarp, 1, 2 steric repulsion in, 111 Extraction processes, 30–34 Z-potentials in, 111 centrifugation, 34 Food guides for citrus fruits, 30 Basic Four, 6 diffusion, 34 Food Guide Pyramid, 6, 133–135 for pome fruits, 30, 31 Forced-air cooling, 9, 10, 12 pressing, 32, 33 Formic acid, as preservative, 17, 18 Free radicals, ionizing radiation-related F production of, 194 Freeze-drying, invention of, 6 Fats Freeze-thawing peeling, 29 bulk density of, 78 Freezing, of fruits and fruit products fruit content of, 140 of semiprocessed fruit products, 17, 18 structural damage during, 129 Feret diameter, of colloidal particles, 112, 113 thermophysical properties during, 75 Fermentation, 3 Freundlich equilibrium curve, 203, 204 Ferulic acid, 148 Frozen fruits, 21–23 Fructose, 138 as browning inhibitor, 164, 192 D-Fructose, 155 Fiber, dietary, 133 Fructose/glucose ratio, 156 Ficin, as browning inhibitor, 187, 193 Fruit products. See also specific fruit products Figs, 4 pH of, 138 Fruits. See also specific fruits dried, 22 biology of, 1, 2 protein content of, 136 classification of, 1, 3 Filter presses, 32–33 definition of, 1 Filtration methods and filters, 42–53 recommended daily servings of, 133 driving force-type, 42 world production of, 1 filter aid and processing, 42, 43 Fruit salads, 22 filtrate in, 42 Fruor, 1 membrane-type, 45–53 G hollow fiber membranes, 47 microfiltration membranes (MF), 46, 47 Galacturonic acid module structures of, 47, 48 in browning, 171, 172 nanofiltration membranes (NF), 46 reverse osmosis (RO) membranes, 46 ultrafiltration membranes (UF), 46–53 operating cycle-type, 42 pressure-type, 42–45 candle filters, 44, 45

Index 223 Galacturonic acid (cont.) Heat capacity, prediction of, 81, 82 methoxylation of, 140 Heating, as juice haziness cause, 36 Heat transport, 73, 74 Gelatin Heat transport properties as browning inhibitor, 207 as clarification agent, 36 calculation of, 75 as fining agent, 35 definition of, 73 thermal conductivity, 73 Genetics, development of, 6 Geometric method, of bulk density measurement, 77, 78 definition of, 82 Glass transition, effect on nonenzymatic measurement and prediction of, 82–86 thermal diffusivity, 73–75 browning, 177, 178 definition of, 83 Glucose, 138 measurement and prediction of, 85, 88 Heavy metals, 152 bulk density of, 78 Heptulose, 139 D-Glucose, 21, 155 Hexanal, as aroma component, 124 Glucose oxidase, 38 flash condensation recovery of, 126 Glutamic acid, 153, 154 Hexanol, as aroma component, 125 Glutamine, 155 flash condensation recovery of, 126 Glutathione, as browning inhibitor, 187, 192 Hexylresorcinol, as browning inhibitor, 187, 192 Glyceric acid, 137 High-intensity pulsed light, 56, 57 Glycine, 136 High-pressure methods, for browning inhibition, 195–197 Gooseberries, 4 High-pressure sterilization, 56–58 Histidine, 136 pectin content of, 140 Honey Granulation, as size enlargement process, 67 as browning inhibitor, 187, 192 Grapefruit as preservative, 3 Horizontal pack presses, 32 frozen, 22 Hot gas peeling, 29 major commercial applications of, 4 Hue, 106, 107 pH of, 138 Hue angle, 184, 185 protein content of, 136 Humidity world production of, 4 in fruit storage facilities, 8, 9 Grape juice during postharvest cooling, 9, 10 canned, 24 Hunter color values, 107, 108 density of, 93, 94 Hydraulic presses, 33, 34 frozen, 24 Hydrocooling, 9–12 5-hydroxymethylfurfural content of, 173 Hydrometric method, of bulk density tartartrates content of, 137 measurement, 77, 78 viscosity of, 91 Hydroxybenzoic acid, 148 Grapes Hydroxycinnamic acid, 148 enzymatic browning in, 162 5-Hydroxymethylfurfural, 199–201 formation of, 172–178 inhibition of, 195, 196 during nonenzymatic browning, 168, 172–178 major commercial applications of, 4 during processing, 175–178 pectin content of, 140 during storage, 172–176 polyphenol oxidase content of I heat-inactivation kinetics of, 183 phenolic substrates for, 163 Ion exchange resins, as browning inhibitors, 199–202, protein content of, 136 205–207 world production of, 2, 4 Grater mills, 31 Iron Greeks, ancient, 3 effect on carotenoid degradation, 157 Grinding mills, 31 fruit content of, 141, 144 Guavas, 4 protein content of, 136 Irradiation starch content of, 139 as browning inhibition method, 193–195 as food preservation method, 6, 56 H Irrigation, invention of, 3 Hammer mills, 31 Harvesting, of fruits, 6–8 Harvest time, 11

224 Index Isinglass, as clarification agent, 36 Lactose, hydrolysis of, 199 Isobutyrate, flash condensation recovery of, 126 Lambert’s law, 100, 101 Isocitric acid, 137 Laplace equation, of heat conduction, 83 Lead, 152 J Lemonade, 3 Lemon juice, canned, 24 Jackfruits Lemons protein content of, 136 starch content of, 139 frozen, 22 major commercial applications of, 5 Juice, 24. See also Apple juice; Grape juice; Lemon juice; pH of, 138 Orange juice; Peach juice; Pineapple juice; Plum protein content of, 136 juice; Prune juice; Tangerine juice world production of, 5 amino acid content of, effect of storage on, 153–155 Leucoanthocyanins, 148–150 appearance of, 99 Lightness. See Luminosity aroma of, effect of storage on, 152, 153 Limes, 5 aroma recovery in, 119 protein content of, 136 canned, 24 Limonene, 118, 119 categorization of, 21 Linalool, 153 clarification temperature for, 40 Liquefaction, enzymatic, 37 cloudy, 109 Longans, 5 processing of, 25, 26 Loquats, 5 viscosity of, 115–119 Lovibond Tintometer, 108 enzymatic browning in, 162 Luminosity, 106 effect on luminosity, 184, 185 effect of enzymatic browning on, 165, 184, 185 inhibition of, 184–186 Lychees enzymatic hydrolysis of starches in, 40, 41 fat content of, 140 frozen concentrated, 24 major commercial applications of, 5 ‘‘natural,’’ 157 protein content of, 136 nonenzymatic browning inhibition in, 196–208 world production of, 5 pasteurization of, 55 Lycopene, 147, 148 powdered, instantizing of, 67, 68 pressurized, 56 M processing of, 21–54 centrifugation method, 34 Maceration, enzymatic, 37 diffusion method, 34 Magnesium, fruit content of, 141, 143 extraction processes, 30–34 Magnus-Taylor pressure tester, 27 final grading, inspection, and sorting, 28, 29 Maillard reactions, 162 front-end operations, 27–29 nonthermal, 56 cysteine-related inhibition of, 189 pressing method, 32, 33 in nonenzymatic browning, 165–172 reception procedures, 27, 28 stages of, 25, 26 basic reactions, 167, 168 semiprocessed, 17 effect of amino acids on, 168, 170, 172 storage-related vitamin loss in, 150 effect of fructose-to-glucose ratio on, 169, 170 world trade of, 21 effect of organic acids on, 171 effect of reducing sugars on, 168, 169, 172 K effect of soluble solids on, 168, 169 effect of temperature on, 171, 172 Kayleigh scattering, 103 kinetics of, 168 Kieselsol, 36 Maleic acid, 137 Kiwifruits, 5 Malic acid, 21, 136, 137, 157 in nonenzymatic browning, 171 protein content of, 136 in peaches, 171 Kumquats, 5 Maltodextran, 177, 178 Maltose, 138, 139 L Manganese, effect on carotenoid degradation, 157 Mangoes Laccase, 207 major commercial applications of, 5 Lactic acid, 137 polyphenol oxidase phenolic substrates in, 163 protein content of, 136

Index 225 Mangoes (cont.) Nonenzymatic browning (cont.) starch content of, 139 restorative methods, 196, 197, 203–207 storage temperature for, 186–176 with temperature control, 196–198 world production of, 5 Maillard reactions in, 165–172 Mango puree´, sugar content, 139 basic reactions, 167, 168 Marmalade, 24 effect of amino acids on, 168, 170, 172 Martin diameter, of colloidal particles, 112, 113 effect of fructose-to-glucose ratio Mature fruit, definition of, 21 on, 169, 170 Meat Inspection Act, 6 effect of organic acids on, 171 Melanins, 162, 181 effect of reducing sugars on, 168, 169, 172 Melanoidins, 166, 168, 204 effect of soluble solids on, 168, 169 Melons effect of temperature on, 171, 172 kinetics of, 168 frozen, 23 phases in, 166 honeydew, protein content of, 136 major commercial applications of, 5 pyrolysis in, 165, 166 world production of, 5 tristimulus parameters for, 168 Mendel, Gregor, 6 Nuts Mesocarp, 1, 2 fat content of, 140 Metabisulfite, as browning inhibitor, 192 protein content of, 136 Metals, fruit content of, 141, 144 2-Methyl-butanol, flash condensation O recovery of, 126 Methyl paraben, as preservative, 8 Octanal, 153 Microwave food driers, 65 Oils, fruit content of, 140 Microwave technology, 6, 56 Olives Milling and millers, 30, 31 Molds (fungi). See also Yeast fat content of, 140 in fruit storage rooms, 8 major commercial applications of, 5 Monochromators, 102 pH of, 138 Mulberries, protein content of, 136 protein content of, 136 Mushrooms, polyphenol oxidase in, 195 world production of, 5 Opacity, 100, 103 N Orange juice aroma of, effect of storage on, 152, 153 Nanofiltration, 46 dehydrated, amino acid content of, 170 Nano-thermosonication, 194 density of, 93, 94 Nectarines 5-hydroxymethylfurfural in, 176 nonenzymatic browning in, 207, 208 protein content of, 136 pH of, 138 world production of, 5 specific heat of, 81 Nephelometry, 103 viscosity of, 91 Nitrogen Orange marmalade, 24 apple content of, 134 Oranges as browning inhibitor, 189, 190 chemical composition of, 135 in modified atmosphere packaging, 15 ester content of, 144, 146 Nitrogen compounds, browning reactions of, 161 major commercial applications of, 5 Nitrogen-containing substances, in fruits, 136 mandarin, protein content of, 136 Nonenzymatic browning, 161, 162, 165–178, 194 navel, 6 absorbance in, 168 pH of, 138 caramelization in, 165–167 storage-related vitamin loss in, 150, 151 effect of glass transition on, 177, 178 world production of, 2, 5 effect of pH on, 171 Organic acids. See also Citric acid; Malic acid; Quinic 5-hydroxymethylfurfural in, 168, 172–178 acid inhibition and control of, 195–208 in browning, 157 as browning inhibitors, 187 factors affecting, 195 fruit content of, 133, 135–137 with ion exchange, 199–202 processing and storage-related miscellaneous methods, 207, 208 preventive methods, 196–202 changes in, 157 with process optimization, 197–199 Orthodiphenol oxidase. See Polyphenol oxidase

226 Index Oxygen Pears diffusion through packaging film, 14–17 bulk density of, 78 effect on plant respiration, dried, 23 in fruit storage facilities, 14 enzymatic browning in, 162 in modified atmosphere packaging, 15 inhibition in, 195, 196 major commercial applications of, 5 P milling processing of, 30, 31 polyphenol oxidase content of Package icing, 9 heat-inactivation kinetics of, 183 Packaging, modified atmosphere (MAP), 13–17 phenolic substrates for, 163 protein content of, 136 advantages of, 14 world production of, 5 browning inhibition inside, 193 disadvantages of, 15 Peas effect on respiration in fruits, 13–16 pH of, 138 Packaging materials, for high-pressure protein content of, 136 food processing, 58 Palletizing (tabletting), as size enlargement Pectic enzymes. See Pectinases process, 67 Pectic substances, ripening-related hydrolysis of, 21 Panthothenic acid, 151 Pectin Papain, as browning inhibitor, 187, 193 Papayas, 5 chemical structure of, 140 irradiation of, 6 fruit content of, 140 Particles. See Colloidal particles viscosity of, 93 Passion fruits, 5 Pectinases, 36, 37 protein content of, 136 activity determination of, 38, 39 Pasteur, Louis, 6, 55 as browning inhibitors, 189, 190 Pasteurization, 6, 55–57 as clarification agents, 36, 171 batch, 55 Pectinesterase, 36, 38–40 high-temperature, short-time (HTST), 55 Pectin esterase, 56 invention of, 6 radiation-related inactivation of, 195 nonthermal, 56, 57 Pectinlyase, 36, 38, 39 of semiprocessed fruit products, 17, 18 Peeling methods, 29 UHT (ultra-high temperature), 55–56 Peel oil, 118, 119 Pasteurized products, 55 Penicillum italicum, 39 Peaches Penicillum spp., 39 browning in, 162 Pentyl acetate, as aroma component, 124 cooling methods for, 12 flash condensation recovery of, 126 dried, 23 Pericarp, 1, 2 frozen, 23 Permeate flux, in ultrafiltration membrane major commercial applications of, 5 filtration, 48–53 mineral content of, 141 effect of volume concentration ratio (VCR) organic acid content of, 171 pectin content of, 140 on, 50–53 pH of, 138 as function of time, 50, 51 polyphenol oxidase phenolic substrates in, 163 stationary, 49, 50 protein content of, 136 Peroxidase, radiation-related inactivation of, 195 storage life of, 12 Persimmons, 5 world production of, 5 fat content of, 140 Peach juice pH acidity of, 171 effect on pectic enzyme activity, 39, 40 amino acid content of, 155, 157 for enzymatic browning inhibition, 194 nonenzymatic browning in, 170, 171 of fruit products, 138 Pear juice Phenolase, 150 enzymatic browning inhibition in, 189, 192 Phenolic acids nonenzymatic browning in, 167 in enzymatic browning, 162, 163 reducing sugars in, 156 subgroups of, 148 viscosity of, 91, 93 Phenolic compounds in browning, 157, 164 as browning inhibitors, 164 as polyphenol oxidase inhibitors, 164

Index 227 Phenolic compounds (cont.) Porosity, 77, 78 as polyphenol oxidase substrates, 163, 164 Postharvest handling, of fruits, 8–12 processing and storage-related changes in, 157, 158 Potassium, fruit content of, 141, 142 Potassium hydrogen tartrate (cream of tartar), 137 Phosphate-based agents, as browning inhibitors, 189 Potassium sorbate, 8 Photometers, 102 Potassium tartrate (Rochelle salt), 137 Photon correlation technique, 115 PPO. See Polyphenol oxidase Phytofluene, 148 Preservation, of fruits and fruit products. See also Pigments, 147–150 Dehydration; Freezing; Storage apple content of, 134 with chemical preservatives, 7, 8 concentration of, relationship to color, 108 of semiprocessed fruit products, 17, 18 effect of processing and storage on, 157 Pressing, as extraction method, 32, 33, 37 natural, 147–150 Pressure, effect on viscosity, 92, 93 Pineapple juice Pressure infiltrates, of antibrowning agents, 191, 192 as browning inhibitor, 193 Pressure sterilization, 56–58 pH of, 138 Proanthocyanidins, 149, 150 Pineapples Processing, of fruits and fruit juices, 21–54 ester content of, 144, 146 clarification and fining processes, 26, 35, 36 frozen, 23 major commercial applications of, 5 centrifugation, 35 pectin content of, 140 concentration, 26, 35 protein content of, 136 filtration, 42–53 storage-related vitamin loss in, 150, 151 of partial concentrates, 35, 36 world production of, 5 enzymatic, 36–41 a-Pinene, 153 extraction processes, 30–34 Pitting, of harvested fruit, 29 centrifugation, 34 Plastic, as high-pressure processing packaging for citrus fruits, 30 material, 58 diffusion, 34 Pliny the Elder, 3 for pome fruits, 30, 31 Plum juice, enzymatic browning in, 193 pressing, 32, 33 inhibition of, 186, 192 front-end operations, 27–29 Plums final grading, inspection, and sorting, 28, 29 enzymatic browning inhibition in, 195 reception procedures, 27, 28 frozen, 23 history of, 2–4 major commercial applications of, 5 overview of, 1–19 pectin content of, 140 Processing facilities, 24 pH of, 138 Process optimization, 197–199 polyphenol oxidase phenolic substrates in, 163 Proline, 153, 170 protein content of, 136 Propranol, as aroma component, 125 world production of, 5 flash condensation recovery of, 126 Polyethersulfone membranes, 207 Proteases, as browning inhibitors, 193 Polygalacturonase, 36, 38–40 Proteins Polymer films, permeability coefficients of, 16, 17 bulk density of, 78 Polyphenol oxidase (PPO) fruit content of, 135, 136 as browning catalyst, 161–163 Proteolytic enzymes, as browning inhibitors, 187 inhibition of, 181 Provitamin A, 148 Prune juice, pH of, 138 with chemical antibrowning agents, 187–193 Prunes, 5, 22 with cold temperatures, 186, 187 color of, 162 with miscellaneous methods, 193–195 Pulps, 17 with thermal inactivation, 183 apple phenolic compound-oxidizing activity of, 162 enzymatic browning inhibition in, 192 phenolic substrates for, 163, 164 enzymatic processing of, 36, 37 Polyphenols, 37 light-colored, 165 in juice, ion exchange resin control of, 199, 200 raspberry Polyvinyl polypyrrolidone (PVPP), 177, 178, 207 color stability of, 158 Polyvinyl pyrrolidone membranes, 207 effect of processing and storage on, 158 Pomegranates, 5 storage-related vitamin C loss in, 151, 152 protein content of, 136

228 Index Pulsed electric fields (PEF), 56 Ripening Pulsed technologies, 56, 57 in harvested fruits, 7 Pumpkins process of, 21 pH of, 138 Rochelle salt (potassium tartrate), 137 protein content of, 136 Romans, 3 starch content of, 139 Room cooling, 9, 10, 12 Puree Rotary drum pressure filters, 42 processing of, 24–26 Rotary presses, 30 Puree´ mango, sugar content of, 139 S Pure´es-marks, 17 Pure Foods Act, 6 Saccharomyces cerevisae, 57 Pycnometry, 78 Sapotes, 5 Pyrolysis, in nonenzymatic browning, 165, 166 Saturation, 106 Pyruvic acid, 137 Saturation index, 184, 185 Scalding, 198 Q Screw presses, 32, 33 Sedimentation methods, for particle size Q10 (temperature coefficient), 184, 186 Quercetin, 163 determination, 113, 114 Quinces, 5 Seeds, of fruits, 1 Semiprocessed fruit products pectin content of, 140 protein content of, 136 categories of, 17 Quinic acid, 157, 171 preservation of, 17, 18 o-Quinone, 163, 187 Senescence, in fruits, 21 Quinones, 158, 162 Serpentine forced-air cooling, 10 Shade, 11 R Shikimic acid, 137 Shimadzu Centrifugal Particle Size Analyzer, 114 Rack and cloth presses, 32 Shrinkage, in dehydrated fruits, 125–128 Radiation, 73, 74 shrinkage coefficient, 127, 128 Radiofrequency (RF) energy, 57 Sieve diameter, 112 Raisins, 23 Silica gel, as browning inhibitor, 207 Silo systems, 27 color of, 162 Sinapic acid, as browning inhibitor, 192 pH of, 138 Sintering, as size enlargement process, 67 Raman scattering, 103 Size enlargement processes, 67–72 Raspberries agglomeration, 67–71 economic importance of, 157 mineral content of, 141 selective (spherical), 71 Raspberry pulp compaction, 67 color stability of, 158 encapsulation, 67 effect of processing and storage on, 158 granulation, 67 storage-related vitamin C loss in, 151, 152 instantizing, 67, 68 Rasp mills, 31 sintering, 67 Reel washers, 28 tabletting (palletizing), 67 Refrigeration, 8-12. See also Freezing Sodium, fruit content of, 141, 143 as enzymatic browning control method, 186, 187 Sodium benzoate, as preservative, 8, 17, 18 Refrigerators, invention of, 6 Sodium bisulfite, as browning inhibitor, 190 Rehydration, 67 Sodium diacetate, as preservative, 8 Relative volatility, 119 Sodium nitrate, as preservative, 8 Resorcinols, as browning inhibitors, 189 Sodium propionate, as preservative, 8 Respiration, in harvested fruits, 7, 8 Soft drinks in controlled atmosphere storage (CAS), 12, 13 invention of, 3 in modified atmosphere packaging (MAP), 13–16 in plastic bottles, 6 Retrograding, of starches, 40, 41 Sorbates, as preservatives, 17, 18 Reynolds’ number, 114 Sorbic acid, as preservative, 17, 18 Rhubarb, pectin content of, 140 Sorting, of harvested fruit, 28, 29 Ripe fruit, pectin content of, 140 Sparkolloid, 36 Specific heat, 73, 74, 80, 81

Index 229 Specific heat (cont.) as taste components, 136 measurement of, 80–82 Sulfiting agents, as browning inhibitors, 187 Sulfur dioxide Specific volume, 73 relationship to density, 79 as browning inhibitor, 187 as preservative, 8, 17 Spectrophotometers, 101–104 Sulfydryl compounds, as browning inhibitors, 188, 193 components of, 101–103 Sumerians, 3 ultraviolet (UV), 102 Surfactants, 7, 8 visible light, 101, 102 Sweetness, of fruit, 21 Syrups, ion exchange treatment of, 199 Spectrophotometry, absorbance, 99–104 Spray drying, 65, 66 T powder recovery process in, 65–67 Tabletting (palletizing), as size enlargement process, 67 Starches Tangerine juice, 24 Tangerines, world production of, 5 fruit content of, 138–140 Tannins, 35, 134, 158 fruit juice content of Tartaric acid, 21, 136, 137 Tartness, 21, 136 enzymatic hydrolysis of, 40, 41 Taste as haziness cause, 35, 36 retrograding of, 40, 41 acidity-based, 136 ripening-related decrease in, 21 sugar-based, 136 Steam, use in fruit processing, 56 Temperature Steam blanching, as enzymatic browning control for agglomeration, 70 method, 182, 183 in dehydration processes, 64 Steam peeling, 29 effect on enzymatic browning, 165 Stefan-Boltzmann law, 74 effect on 5-hydroxymethylfurfural formation, 175, 176 Steric repulsion, 111 effect on modified atmosphere packaged fruit, 16 Sterile products, 55 effect on viscosity, 92, 93 Sterilization techniques, 56, 57 for fruit juice clarification, 40 Stokes’ law, 112–114 in fruit storage facilities, 9 Storage, 7 in pasteurization, 55, 56 controlled atmosphere (CAS), 12, 13 Temperature coefficient (Q10), 184, 186 refrigerated, 8–12, 186, 187 Terpinene-4-ol, 153 relative humidity during, 8, 9 Terpinolene, 153 temperature during, 9 Texture, measurement of, 7 effect on ascorbic acid (vitamin C) content, Thermal conductivity, 73 definition of, 82 150–152 measurement and prediction of, 82–86 Storage life, postharvest, 6, 7 Thermal diffusivity, 73–75 Strawberries definition of, 83 measurement and prediction of, 85, 88 canned, pigment instability in, 158 Thermal methods chemical composition of, 135 for browning control mineral content, 141 D value in, 183 pectin content, 140 elevated temperatures, 182–186 protein content, 136 in enzymatic browning, 182–187 cooling methods for, 12 Q10 value in, 184 major commercial applications of, 5 refrigeration-related methods, 186–187 pH of, 138 as scalding cause, 198 storage life of, 12 Thermal radiation, 73, 74 world production of, 5 Thermodynamical properties Stress crack formation, 126 definition of, 73 Succinic acid, 137 enthalpy, 73, 80 Sucrose, 138 specific heat, 73, 74, 80, 81 hydrolysis of, 155, 156, 169 measurement of, 80–82 Sugar/acid ratio, 6, 7, 21, 136 specific volume, 73 Sugars. See also Fructose; Glucose relationship to density, 79 effect of storage on, 155, 156 as energy source, 138 fruit content of, 133, 135 hydrolysis products of, 155 ripening-related increase in, 21 specific heat of, 81

230 Index Thermophysical properties, 73–98 Van der Wall’s (dispersion) forces, 68, 69, 203 density, 73, 74, 77–79 Vegetables. See also names of specific vegetables enthalpy, 73, 74, 80 experimental data and prediction models for, 76–95 fruits classified as, 1 during freezing, 75 vitamin content of, 144 identification of, 73–75 Viscosity specific volume, 73, 74 of cloudy fruit juices, 115–118 viscosity, 73, 74 definition of, 85, 86 of cloudy fruit juices, 115–118 effect of temperature and pressure on, 92, 93 definition of, 85, 86 measurement of, 87–94 effect of temperature and pressure on, 92, 93 measurement of, 87–94 in Newtonian fruit products, 89–91 Newtonian, 85–87, 89–91 in non-Newtonian foods, 88, 89 in non-Newtonian fruit products, 91, 92 Tin, 152 Newtonian, 85–87, 89–91 Tomato concentrate, viscosity of, 93 Vitamin(s), 141 Tomatoes, protein content of, 136 fruit content of, 135, 144, 145 Tomato juice, pH of, 138 processing and storage-related destruction of, 150–152 Tomato paste, viscosity of, 93 vegetable content of, 144 Top icing, 9, 11 Vitamin B1, vegetable content of, 144 Total anthocyanin (TA), 99 Vitamin B6 Trans-2-hexenal, as aroma component, 124 processing and storage-related destruction of, 151 vegetable content of, 144 flash condensation recovery of, 126 Vitamin C. See Ascorbic acid Translucency, 103 Vitamin E, vegetable content of, 144 Transparency, 103 Vitamin K, vegetable content of, 144 Trimming, of harvested fruit, 29 Volatile compounds, of fruit aroma, 146–147 Tristimulus colorimeters/colorimetry, 99, 104–108 Volatility of the volatile, 119 Volume fraction of particles (Ø), 116 CIELAB method, 106–108 Trucks, refrigerated, 12 W Tryptophan, 136 Turbidimetry, 103 Washing, of harvested fruit, 27, 28 Turbidity, 103 Water Tyrosine, as polyphenol oxidase substrate, 163, 164 bulk density of, 78 U fruit content of, 21, 133–135, 145 Water content, effect on thermophysical properties, 75 Ultrafiltration Watermelons as enzymatic browning inhibition method, 193–195 cooling methods for, 12 polyvinyl polypyrrolidine-based stabilization of, 207 storage life of, 12 Web scrubbers, for powder recovery, 65, 66 Ultrafiltration membrane filtration, 46–53 Well water, 11 permeate flux in, 48–53 Whiskey distilleries, 3 as function of time, 50, 51 influence of volume concentration ratio (VCR) on, X 50–53 stationary, 49, 50 Xanthophyll, 147–148 Xylose, 139 Ultrapasteurized products, 55 Ultraviolet light processing, 56 Y Ultraviolet pressure processing, 56 United Nations Food and Agricultural Organization Yeast, removal from fruit juice, 35 (FAO), 1, 2 Z Unripe fruit Zinc enzymatic browning rate in, 164, 165 fruit content of, 144 pectin content of, 140 orange juice content of, 152 V Z-potentials, 111 Vacuum cooling, 9 Vacuum infiltrates, of antibrowning agents, 191, 192