Cooking Food 🔥
Why do we cook food? (Reasons for cooking food)
Methods of heat transfer
- Develop colour, aroma and flavour of food
2. Improve digestibility
3. Improve food safety and keeping quality
1.Conduction
- Convection
- Radiation
heat travels from the heat source to the food by direct contact. heat cause molecules in the frying pan to vibrate more vigorously and collide with one another to vibrate more as well. heat is transferred from the heat source continuously --> to the frying pan --> to surface of the food --> to centre of the food
Example: 🐓Chicken when roasted, skin becomes golden brown with attractive aroma and flavour, making the dish more appetising.
Example: Soften the cellulose of the green leafy vegetables, 🥦making it easier to chew and swallow.
🥛Heat used in cooking kills in harmful microorganisms, which reduces the risk of food poisoning. Example Raw soya beans contain toxins that needs to be boiled to make it safe to consume
example: a piece of beef steak is cooked through conduction
heat is transferred by the movement of liquid or gas. as liquid or gas is heated, the hotter portion rises, while the cooler portion sinks, creating a convection current. this current passes energy from the hot liquid or gas to the food.
example :cake batter or chicken in the oven by the movement of hot air created by convection currents
transfer of energy from the heat source to the food in the form of infrared waves or microwaves. without a medium for heat transfer
example, grilled meat absorb heat from infrared rays emitted by hot charcoal and gets cooked
Different methods of cooking
dry heat
baking, dry frying, stir-frying/sauteing, shallow frying, deep frying and grilling
moist heat
boiling, steaming and simmering
others
microwave cooking
baking. definition: food is placed in hot enclosure (e.g. hot oven) and preheated from 150 to 220C to make sure food starts to cook immediately. heat transfer: conduction, convection and radiation. advantage browning of the food surface as well as flavour and texture. more food can be baked at the same time. healthier cooking method as little or no oil is used disadvantage: high temperature lead to loss of heat sensitive vitamins and slow cooking method and high energy consumption
grilling definition: by placing food on top or below a heat source (e.g. glowing charcoals) and brushed with a thin layer of oil to prevent charring and improve flavour. heat transfer: radiation by infrared waves. advantage: relatively quick method of cooking, most nutrients are well retained, browned surface and distinctive flavour, and texture, low fat cooking method disadvantage:, constant attention, loss of b group vitamins and vitamin c, risk of carcinogen compounds
example cooking thin or tender cuts of meat, sausages, seafood and thinly sliced vegetables
example starchy or flour based food - potatoes and cakes, poultry and fish
dry frying definition food is cooked in its own fat. food high in fats