Nutripro Magazine Healthy Cooking Methods

FOOD N° 2 6 / 06 COOKiNG CONTENTS METHODS • Moist-heat cooking methods – Boiling – Poaching – steaming – stewing/Braising – Pressure cooking – Microwave cooking • dry-heat cooking methods – Roasting – sautéing – grilling – Baking • Fry-cooking methods – deep-frying – Pan-frying – stir-frying/Wok

2 Cooking Methods Moist-heat • When practical, save the cooking Steaming: cooking liquid for use in stocks, sauces and m­ ethods casseroles. Cooking at a temperature of about 100°C (212° F) in steam, with the food • To add vitamins, sprinkle some and cooking liquid completely sepa- fresh herbs onto the cooked food. rated. You can use a commercial steamer or a pot with a rack that Generally, moist-heat cooking meth- Poaching: suspends the food above a small ods use a liquid for cooking – usually amount of simmering liquid. water, stock or steam. The advan- Cooking in liquid at a temperature Tips: tage of steam is that it transfers more under the boiling point (75°– 95° C / • Use a flavoured liquid like stock, heat at the same temperature. As a 167°– 203° F). result, the food cooks faster and Tips: wine, water infused with herbs, fewer nutrients are lost. The cooking • Not ideal for nutrient retention in lemon, etc. temperature may vary from 70° – 120° C (158° – 212° F). These methods vegetables and potatoes, because a Stewing / Braising: are particularly suitable for prepar- long cooking time results in addi- ing pasta, rice, pulses and vegeta- tional nutrient loss through osmosis Meat is often browned before liquid bles. The methods referenced below, (nutrients boiled out into the liquid). is added. Meats and vegetables can though not exhaustive, are the more • Use a pot with a large diameter. be cooked or steamed in their own common techniques. • If possible, add herbs or spices to juice. A particular way of stewing the poaching liquid rather than salt is to glaze: vegetables (carrots, small Boiling: or sugar. onions) become covered with the stew stock, which is reduced and Cooking in a lot of liquid at a tem- ­enriched with a little sugar. perature of about 100° C (212° F). Tips: • Generally use as little water as ­possible to minimize the loss of ­vitamins and minerals. GOOD TO KNOW GOOD TO REMEMBER Blanching +Moist-heat cooking methods Nutrition – Food Purpose: • Deactivation of enzymes Boiling • food (e.g. vegeta- • no fat / oil is needed • great loss of nutrients bles) for soups; (osmosis) e.g. water- • Preservation of the colour hot pots soluble vitamins (folate, vitamin B1, C) • Killing of microorganisms that may • starches such as be present rice, potatoes and pasta Note: loss of about 20 – 30% of vitamin C, but vitamin retention improves Poaching • meat with little • no fat / oil is needed • great loss of nutrients during subsequent storage (chill- connective tissue freeze process). Tips: • eggs, fish, poultry, • Drain and refresh in cold or iced small sausages w­ ater immediately to prevent fur- Steaming • vegetables, fish, • nutrient-friendly – ther vitamin loss through cooking. method • potatoes • Do not leave the food in the water as this will cause further loss of • minimal loss of ­nutrients through osmosis and will vitamins soften the texture of the food. Note: Osmosis: Nutrients in food leak or diffuse to liquid with lower con- centration. Therefore, it is important to use this liquid for the sauce or as stock for soups because it is rich in vitamins and minerals. NutriPro Food 6/06

3 Cooking Methods Tips: Tips: GOOD TO KNOW • Use leftover water for the sauce • It is important to keep to the e­ xact Phytochemicals or as stock for soups. cooking time, as the food over- • Use a pot with a tight-fitting lid cooks very quickly. The term phytochemicals refers to a • Suitable for producing large batches class of substances (at the moment (as wide and flat as possible). (portion by portion) of food (vegeta- 60 000 – 100 000 are known), which bles, potatoes, fish), or for producing exist only in plants. They are classi- Pressure cooking: a smaller amount of food (e.g. for fied into several groups (e.g. carote- diet recipes). noids, flavonoids, phytoestrogens, Cooking in an airtight pressure glucosinolates) and rated as health- cooker at about 105° – 120° C supporting substances. They have, (221° – 248° F). for example, antioxidant, anti-carci- Note: higher temperature equals nogenic and anti-inflammatory shorter cooking time. The steamer is ­effects and may also reduce blood also suitable for blanching, poaching cholesterol. These effects can only and reheating. be verified when the phytochemi- cals are obtained from whole foods in fruits and vegetables. Their effect when taken as supplements cannot currently be verified. Their loss dur- ing cooking varies greatly. Some are soluble and sensitive to heat and air; others are better obtained from well-done foods (lycopene in cooked tomatoes). Tip: The best way to serve a variety of phytochemicals is to create a diet that includes every colour of the rainbow (red, orange, yellow, green, blue/violet). NutriPro Food 6/06 – NESTLÉ Professional Nutrition Magazine

4 Cooking Methods GOOD TO KNOW Microwave cooking: Dry-heat cook- ing methods How does a microwave Cooking with electromagnetic waves, work? either with or without a small amount Heat is transferred through air or fat. of added liquid. The food can be The cooking temperature is between In other cooking methods food browned or given a crust only if com- 120° – 150° C (248° – 302°F), and for warms up from the outside in. But bined with a dry-heat method such short periods up to 300°C (572° F). with the microwave, the heat comes as grilling. It is ideally suited for Suitable for foods rich in proteins, from inside the food, from its water r­ eheating food. like meat, fish and seafood and molecules. The electromagnetic Tips: where a crust is desired. waves of the microwave cause these • The food may cook unevenly and water molecules to vibrate and Roasting: the resulting heat cooks the food. have hot and cold spots. Deciding factors for determining Note: Cooking with browning on the stove the required cooking time of certain ––For liquids: stir about halfway or in the oven with or without products can be water content, ­adding fat, at a temperature of m­ olecular density, the starting tem- through the cooking time to dis- 140°– 200°C (284°– 392° F). A special perature of the food, as well as the tribute heat more evenly. form of short roasting is sautéing. penetration or strength of the rays ––For solid food: let sit for several Tips: (normally 2 – 4 cm). According to minutes after cooking or reheat- • Important: roast at intense heat to current findings there is no risk of ing, before serving. radiation exposure if microwave • If the thickness of food (e.g. piece of seal the juices inside the meat, ­ovens are used properly. meat) is more than the penetration then cook at low heat until done. of the microwaves, there is a risk of This reduces the loss of vitamins, the core remaining raw. As a result, minerals and moisture. any existing microorganisms (e.g. • Use vegetable oils that are high in salmonellae in poultry) may not be polyunsaturated or monounsaturat- killed. ed fats like canola oil and sunflower • Frozen products do not conduct oil. Roast meat in its own juice. heat well, so there is a risk of the • Brush vegetables with a minimum outside area overheating while the of oil to decrease fat absorption inside remains raw. during cooking. Note: defrost on low heat and cook • For a low-fat meal: do not serve or immediately. eat the crust as it contains the • Suitable dishes: glass, porcelain, roast’s fat. and microwave-safe plastic dishes. Remove the dark brown or black crust before eating, as it could con- GOOD TO REMEMBER tain carcinogenic (cancer-causing) substances. Moist-heat cooking methods Nutrition – • A special method: cooking at a low temperature – cook the meat at a +Food temperature between 68°– 80° C (154,4°– 176°F) in the oven until Stewing/ • vegetables (e.g. • vitamin and mineral • addition of some fat done (up to 24 hours). Braising filled vegetables), retention if cooking if used for cooking or • Roasting in the pan or grilling bet- fruits liquid is kept for fur- fat released from ter preserves the vitamins and ther use meat during cooking minerals in meats, fish or chicken • fish, meats (with which is then ab- than roasting in the oven or boiling, more connective • light cooking method sorbed by the sauce due to heat, cooking time and loss tissue) of nutrients. • nutrient-friendly • heat-sensitive vita- method mins are partially d­ estroyed • minimal loss of vitamins – Pressure • see boiling, • comparable with – cooking steaming, stewing steaming and stewing • reheating • less cooking time Microwave • any kind of food • minimal loss of vita- mins and minerals cooking but only in small • short cooking time quantities NutriPro Food 6/06

5 Cooking Methods Sautéing: • Place food on a rack so fat can GOOD TO KNOW drain.When using a grill plate sim- Dry-heat cooking method in which ply brush the plate with a mini- Cook & Chill heat is conducted by a small amount mum of oil (polyunsaturated or mo- of fat (the food is kept in motion). nounsaturated vegetable oil) before Cook & chill is a food preparation Tips: heating. Never grill cured (pickled) system, not a cooking method. • Use for tender cuts of meat and meat, because cancer-causing The principle: the food is cooked to ­substances (nitrosamine) may be 90 – 95% (depending on the system of vegetables. formed. regeneration/reheating), and all of • If meat is marinated, dry before the cooking methods described here • Avoid overly moist marinades or may be used, except grilling. cooking to ensure proper ­browning. fat dripping from the grilled food This is followed by shock-chilling • Cook only single layers, don’t over- onto hot coals or heating elements, to a temperature of 1° – 3° C as this may cause toxic compounds (33,8° – 37,4° F), packing the food in crowd the pan. to be released into the resulting single or multiple portion contain- smoke. ers, and storing. The storage time Grilling: depends on the special cook & chill Baking: method and lasts between 3 and 21 Cooking with radiant heat or contact days. The rapid cooling ensures heat, with or without added fat. Cooking with browning in dry heat m­ inimum vitamin and mineral loss. Grilling techniques: at a temperature of 120°–250°C The loss of vitamins depends on Over-heat grilling: food is placed on (248°– 482°F). the choice of cooking method and a rack or grill over a gas, charcoal or on the storage time. barbecue grill. Note: the longer the food is stored, Under-heat grilling: food is placed the greater the vitamin loss. ­under a gas or electric salamander or heating element. Between-heat grilling: this method uses radiant heat, convection heat or a combination of both. Tips: • Dry meat browns better than moist meat. The grill must be hot before the food is added. This way the juic- es are quickly sealed into the meat and are better retained, as are vita- mins and minerals. • Don’t salt the food before grilling. Salt draws the juices out of the meat, resulting in a loss of vita- mins, minerals, and moisture. GOOD TO REMEMBER Dry-heat cooking methods + Nutrition – • sometimes no fat added through • heat-sensitive vitamins are par- Food cooking tially destroyed Roasting • meat, fish • some loss of water/fat vitamins if • vegetables, potatoes stock is not kept for the sauce • eggs • if fat is used, the fat content of the food becomes higher • formation of acrylamide Grilling • fish, meat (food with not • fat drains out • heat-sensitive vitamins are Baking much connective tissue) ­partially destroyed • vegetables, potatoes • no loss of vitamins and minerals • heat-sensitive vitamins are • fruit into liquid ­partially destroyed • dough products • potatoes • hard digestible dough and crusts • formation of acrylamide become light and easy to digest NutriPro Food 6/06 – NESTLÉ Professional Nutrition Magazine

6 Cooking Methods GOOD TO KNOW Fry-cooking Pan-frying: methods The forming of a­ crylamide A special form of deep-frying; brown- Cooking with browning in hot oil ing raw or prepared foods in shallow Acrylamide is formed from proteins at a temperature of 140° – 190°C amounts of fat. and sugars in potatoes and cereal (284°– 374°F). The methods are Tips: products at temperatures over d­ efined according to the amount of • Cook at proper temperature and 100° C (212° F). It is only produced fat used. Correct frying of potatoes through the dry-heat cooking meth- and vegetables preserves vitamins make sure the food is well-breaded; od during the browning stage. and minerals better than boiling or this minimizes fat absorption and steaming, but increases the amount sogginess in the finished products. Note: of fat and energy. • The amino acid asparagine and Stir-frying / Wok: Deep-frying: sugar (glucose, fructose) are the A traditional Chinese method for main precursors of acrylamide. The food is entirely submerged c­ ooking food in a frying pan in hot fat. (e.g. wok) with a small amount of oil. • Acrylamide content increases con- Tips: • Soak food in a low-fat marinade sistently with higher temperatures • Fry as quickly as possible. Longer and longer cooking times. before cooking. This may be all the Acrylamide may cause cancer. frying time increases fat absorp- oil necessary. At this time there is no maximum tion. • Use spray oil or a pastry brush to for the reception of acrylamides. • The smaller the food being fried, coat food to avoid higher fat ab- the greater the amount of fat sorption or coat the pan with a Tips for reducing the content of ­absorbed. minimum of oil. ­acrylamide: • The higher the fat content of the • Non-leafy vegetables (e.g. broccoli, • Avoid heavy roasting in favour meat, the less oil is absorbed. shredded carrots) absorb about as • To reduce the formation of acryl­ much oil as leafy vegetables. of light browning. amide, fry at maximum 170° C • If food sticks to the pan during (338° F) for a slightly longer time. cooking, add a little stock or water • Boil potatoes before roasting. • Drain the food of oil before ­serving. rather than oil. • Avoid reusing the frying oil. • Bake at a maximum temperature • When oil smokes, throw it away of 180° C (356° F) in an oven with immediately. It may become toxic, air circulation, 200° C (392° F) producing free radicals. in an oven without air circulation. • Fry at a maximum temperature of 170° C (347° F) and in small por- tions. Proportion of frying food to oil should be 100 g to 1 – 1,5 l. • French fries: thick fries are better than thin ones due to surface area. GOOD TO REMEMBER Fry-cooking methods + –Nutrition Frying Food • no loss of water-­ deep-frying: soluble vitamins • meat, fish, • high absorption of shellfish • only a small amount fat (energy rich) of heat-sensitive vi- • vegetables, tamins are destroyed • formation of acryl- potatoes, amide • possible increase of • poultry vitamin E based on oil used for cooking NutriPro Food 6/06

7 Cooking Methods Vitamin loss – Canned vegetables: GOOD TO R E M E M B E R • Never boil canned vegetables. Tips to prevent • The best way to heat them is the Stability of vitamins vitamin loss: microwave warm up the liquid first, then add the Vitamin Acid Alkali Heat Light O2 • Whenever possible, wash vegeta- v­ egetables. low pH high pH >70°C bles whole and before peeling • Avoid excessive stirring while ­under running water. w­ arming. C • Use the juice to cook the vegeta- • Peel thinly or cook with skin on. bles in, or add to soups or stocks. B6 • Cut into large pieces. A • Raw vegetables and fruit salads: – Frozen vegetables: • Don’t thaw them before cooking. D add a little lemon juice or vinegar • Heat the water first, then add the to slow down vitamin C loss. vegetables. E • Use the smallest amount of water • If you use them for cold food necessary. items, cook them thoroughly no effect sensitive very sensitive • Cook with the lid on. b­ eforehand. • Cook until just tender, not mushy. • The best way to heat them is in water-soluble vitamins (C, B vitamins) • Serve immediately keeping food the microwave (less vitamin loss). fat-soluble vitamins (A, D, E, K) warm causes a vitamin C loss of 4 – 17% in one hour and GOOD TO KNOW 7 – 34% in two hours. Vitamin loss by different cooking methods Cooking Vitamin loss methods in % (C, B1, B2, B6) Boiling 35 – 60 Poaching Less than boiling Steaming 10 – 25 Pressure cooking 5 – 10 Microwave cooking 5 – 25 Roasting 10 – 47 Stewing/Braising 10 – 12 Grilling 10 – 12 Baking 10 – 12 Frying 7 – 10 1. Which of the following cooking Quiz 7. What is important to remember, methods is a moist-heat cooking if you use frozen vegetables? method? 4. For which cooking method can you use a steamer? N Don’t thaw them before cooking A Grilling I Add lemon juice to cooking S Poaching I Boiling C Baking T Roasting l­iquid to slow down vitamin C A Stewing loss 2. Which of the following cooking R Use a lot of fat methods is a dry-heat cooking 5. With reference to fat intake, which method? cooking method is ­better? 8. Which cooking method causes the greatest vitamin loss? U Steaming M Deep-frying L Pressure cooking A Stir-frying R Microwave cooking T Roasting T Pan-frying P Baking G Boiling 3. What is the reason for b­ lanching 6. How are vitamins classified? vegetable? I Water-soluble and 1 2 3 4 5 6 7 8 O To increase vitamin loss fat-soluble substances R To soften the texture of A Major and trace substances the food Answer: STEAMING E To minimize vitamin loss during storage NutriPro Food 6/06 – NESTLÉ Professional Nutrition Magazine

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