Effects of heat on food

Effects of Heat on Food and Cooking

Methods

Effects of Heat on Foods

• Coagulation – exposure of proteins to excessive heat toughens them and makes them dry. Most proteins complete coagulations or are cooked at 71’C to 85’C

PROTEINS

• By cooking properly, tough meats can be made tender.

• Acids, like lemon juice, vinegar and tomato products do two things to proteins:

1. speed coagulation 2. help dissolve some connective tissue

CARBOHYDRATES

• Caramelization

• Gelatinization

• Acids inhibits gelatinization

FRUITS AND VEGETABLES

• The softening of fruits and vegetables in cooking is, in part, the breaking down of fiber.

• Sugar makes fiber firmer

• Baking soda makes fiber softer.

FATS

• When fats are heated, they begin to break down.

Smoke point – the temperature at which the fat deteriorate rapidly and begins to smoke.

MINERALS AND VITAMINS

• Mineral components may be leashed out, or dissolved away from foods during cooking.

• Vitamins and pigments may also be destroyed by heat, by long cooking and by other elements present during cooking.

HEAT TRANSFER

A. Conduction

B. Convection

C. Radiation

1. When heat moves directly from one item to something touching it.

A. Conduction

2. When heat moves from one part of something to an adjacent part of the item.

B. Convection

1. Natural – hot liquids and gases rise while cooler ones sink.

2. Mechanical – heat is transferred more quickly to the food and the food cooks faster.

C. Radiation

1. Infrared – an electric element or ceramic element heated by a gas flame becomes so hot that it gives of infrared radiation which cooks the food.

2. Microwave – the radiation generated by the oven penetrates partway into the food, where it agitates the molecules of water.

COOKING METHODS

1. Moist-Heat Methods

Those in which the heat is conducted to the food product by water or water-based liquids such as stock and sauces or by steam.

2. Dry-Heat Methods

Heat is conducted without moisture, that is by hot air, hot metal, radiation or hot fat.