Food Science Flashcards
Reasons why we cook food
- to destroy harmful bacteria
- to develop flavour
- to change the colour (make it more attractive)
- to make it easier to digest
- to make food safe to eat
Methods of heat transfer
Conduction
Convection
Radiation
Colloidal structure
Is formed when two or more ingredients are mixed together
Flour
Bulks up ingredients
Forms main structure of product
When does dextrinisation occur ? Example ?
When dry heat I used on flour and the product becomes brown, the dry heat turns the starch into sugar.
E.g. toasting or baking
Gelatinisation (D)
When flour is mixed with a liquid, and the mixture thickens in the presence of moisture and heat
What happens during gelatinisation ? Temperatures ?
60 degrees - starch grains swell
80 degrees - starch grains burst and thicken
100 degrees - mixture boils
What does sugar do ?
Adds flavour
Adds colour
Caramelisation
It is when the sugar changes colour
Occurs at 154 degrees
Uses of sugar
Preserving - prevents growth of microorganisms
Aerating - when sugar is beaten with eggs
Bulking out ingredients - e.g. biscuits
Uses of fats (5)
Aeration - fat and sugar are creamed together trapping air
Shortening - fat coats the grains of flour and prevents gluten from developing (crumbly texture)
Flavour and moisture - butter (also means they have a longer shelf life)
Emulsions - oil and liquid are mixed
Frying - adds flavour and texture (crisp)
Eggs ( coagulation )
Coagulate when moist or dry heat is applied to them
Egg white coagulates at 60 degrees
Egg yolk coagulates at 80 degrees
Symeresis
When protein is over cooked
Uses of eggs (6)
Aeration - eggs are whisked, they trap air, can create a foam (just egg white)
Form an emulsion when mixed with fat, stops it separating
Adds colour - in sauces or as a garnish
Binding - e.g. fish cakes
Glazing - makes food more attractive
Enriching
Coating
Acid uses
Give flavour (sharp or sour)
Used to tenderise meat, break down the structure of protein
