ocr food preparation and nutrition- section C: cooking and food preparation

give 3 reasons why we cook food

destroy harmful bacteria, improve flavour and make it more attractive

what is conduction heating and example

where heat is transferred from one molecule to another e.g boiling

what is convection heating and example

where warm molecules rise and the cooler molecules fall closer to the source of heat e.g baking

what is radiation heating and example

where heat is passed by electromagnetic waves from one place to another e.g microwaving

temperature to simmer

85-99 degrees C

temperature to poach

85 degrees C

what is blanching

putting cooked food straight into ice cold water to stop enzyme action

what is braising

meat is browned in pan using a bit of fat then put in container with liquid and covered by a lid

4 types of frying

pan frying, dry frying, stir frying, deep frying

how do microwaves work

penetrate food and cause molecules to vibrate by radiation which causes friction when they vibrate against each other producing heat and water molecules continue to vibrate and generate heat after removed from microwave

what is coagulation

change in structure protein by heat, acids or mechanical action (to set something)

what is a colloidal structure

when 2 substances are mixed together

what is an emulsion

a mixture of 2 liquids

what is dextrinisation

when dry heat is applied to flour and it browns as the starch is changed into a sugar

what is caramelisation

at 154 degrees C the sugar changes colour from white to brown

what is a maillard reaction

when food containing proteins and carbs are cooked by dry heat methods they turn brown

what is aeration

trapping air into a mixture

what is an emulsifier

a substance that stops water and oil from seperating

what is plasticity

The ability of a solid fat to soften over a range of temperatures

what is shortening

When fat coats the flour grains and prevents the gluten from developing and absorbing the water, resulting in a crumbly mixture

what is denaturing

when proteins are heated or have acid added or mechanical action their chemical structure is changed

egg coagulation temperatures

egg white coagulates at 60 degrees C from opaque to white

egg yolk coagulates at 70 degrees C

when does syneresis happen

when egg is heated too quickly the liquid separates out and protein becomes tough

what is the protein and enzyme in egg whites

albumin and lecithin

what is oxidation

when fruit and veg are cut and their cells are exposed to air

what is enzymic browning

the reaction between a food product and oxygen resulting in a brown colour

3 ways to aerate mixtures

creaming, beating and sieving

2 proteins in wheat

gliadin and glutenin

how to do a triangle test

give someone 3 samples- 2 the same 1 different and ask them to identify odd one out (used for small changes)

what are high risk foods

foods which are ideal medium for growth of bacteria (moisture, food, oxygen and warm)

danger zone for bacteria

5-63 degrees C

what is a shelf life

how long a product can be kept safely and remain of high quality

what is cross contaminaton

when microorganisms transfer from raw to cooked food causing infection