Effects of cooking (will come up) Flashcards
What happens when proteins are cooked
The proteins denature (strands unravel) and coagulate
The structure of each protein is irreversibly changed by heat, acid or alkali resulting in a loss of moisture, shrinkage and becoming firm
Example of a protein being cooked
Egg whites changing from a clear liquid to a white solid
Nutritional effect on denatured protein
It is generally unchanged
Most denatured proteins are more easily digested by the body
What is the maillard reaction
When proteins and a carbohydrate are heated with a dry heat, many different flavour compounds are created
What happens when fats are cooked
As fats contain a small amount of water, they soften then liquefy when heated - this property is called plasticity and reflects the fact fat cannot evaporate
What does fat add to food once heated
Colour and flavour to foods
A shortcrust pastry would need to made using a hard fat
Why
It would melt slower than a soft fat
Main reasons why food is cooked
To make it easier to digest
To develop flavours,
To improve texture and appearance
To make it safe to eat (to avoid food contamination)
What is conduction
The transfer of heat by direct contact from a hot surface, heat passes through the base of the pan into the water
Eg lamb chops, bacon sausages touching the hot surface of a frying pan
Uses - dry frying, griddling, searing
Diagram - base of pan on fire
What is convection
The transfer of heat by the mass movement of heated particles into a cooler mass or area, the heat moves around by a convection current
Eg hot water, air or oil surrounding the food such as boiled potatoes, roast beef
Uses - dry heat - baking, roasting
wet heat - boiling, braising, simmering
Diagram - Arrows moving around in a fan oven or in a pan of water
What is radiation
The transfer of heat using electromagnetic radiation: waves of heat or light strike the food. No physical contact between the heat source and food being cooked,
Eg waves of heat pass through the air from the grill to make the surface of the bread go brown.
sausages bacon, kebabs
Uses - toast, grilling and bbqing foods
Diagram - arrows coming down from a heat source eg grill and going towards food
How to retain water soluble vitamins (green veg)
Cook in as little water as possible Cook for as short time as possible Use the cooking water for gravy Chop and prepare veg just before needed Steam instead of boil Do not presoak
Why may a sponge sink
Why may a sponge sink
Underbaked
Undermixed
Why may a sauce goes lumpy
Too much flour
Not enough milk
