functional properties of food Flashcards
What is coagulation (proteins)?
The changing of a protein from a liquid to a solid when heated or agitated. eg:
When an egg is cooked both the liquid yolk and white will become firm and change colour.
what is denaturation?
Refers to a permanent change in the structure of the protein in food.
what is emulsification?
Joining together ingredients that don’t normally mix. E.g:
Creating a stable mixture of oil and water; butter, ice cream, milk, salad dressings, mayonaise.
what is emulsification?
What is aeration?
The process of incorporating air into food products, can be done mechanically, chemically, or biologically eg:
cake, mouses and meringues
what are the browning reactions?
dextrinisation, caramelisation, and enzymatic browning.
what is dextrinisation?
Starch + dry heat = browning
occurs when food containing starch (which is a type of carbohydrate) is cooked by a dry heat method (such as baking, roasting, grilling or frying) and the starch changes to dextrin’s, causing the food to become brown.
e.g: toasting of bread
what is caramelisation?
When sugar is heated to a high temperature, it will melt and become a brown liquid. e.g:
1) toffee
2) caramel sauce
3) fruit cakes
4) brulee
Caramelisation occurs in dry heat cooking methods. The browning of vegetables with a high sugar content, such as carrots and sweet potatoes, is likely to be caused by caramelisation.
what is enzymatic browning?
Enzymatic browning occurs in particular raw fruits and vegetables that are peeled and exposed to air. Oxygen activates enzymes in fruits and vegetables – such as bananas, apples and potatoes – causing a chemical reaction and resulting in surface browning.
what is maillard reaction
when food is heated resulting in the browning of a foods outside e.g: cooked meat, cakes.
Protein + sugars + heat = browning
What is Geletinisation?
Starch dissolves in liquid when heated, causing thickening.
The starch substance in a recipe can be flour, cornflour or rice, and is often referred to as the thickening agent.
Cakes, sauces and gravies rely on the gelatinisation of starch for their consistency.
What is an emulsifier?
An ingredient added to a mixture to prevent it from separating which is attracted to both oil and water, allowing the two to mix.
What is the natural emulsifier egg yolk contains?
Lecithin
Where is lecithin found (2 examples)
1) Egg yolk
2) Soy beans
3) Sunflower seeds
What are 3 examples of denaturation?
1) Adding heat
2) Mechanical action
3) Adding acids or alkali (causes amino acid chains to uncoil)
What are examples of coagulated foods?
1) cheese (formerly milk)
2) cooked egg (formerly raw)
3) cooked meat (formerly raw)
what happens when you overcool protein foods? (over-coagulation)
The product becomes dry and tough because the protein shrinks and forces the moisture our. This is evident when meat or poultry is over cooked.
What is another term for chemical and biological aeration?
leavening
What is an ingredient used for biological aeration
Yeast; is a single-celled microorganism that gives off carbon dioxide during growth – it needs food (sugar), moisture and warmth to grow (e.g. used in bread making
What are some examples of mechanical aeration?
Whisking and beating (meringues, whipped cream), sifting, rubbing in (rubbing in butter into flour for biscuits)
What is chemical aeration? + examples of ingredients used.
Where Chemical raising agents are a mixture of acid and alkalis in a ratio of 2 parts alkali to 1 part acid.
The acids and alkalis react in the presence of moisture to give off carbon dioxide gas.
The carbon dioxide can be produced in a number of ways:
-Self-raising flour: contains baking
powder
-Bicarbonate of soda plus an ingredient with acids, e.g. cream of tartar, sour cream, milk, golden syrup, citrus or fruit juice
-Baking powder: a mixture of an acid and an alkali with rice flour to prevent the chemical from reacting.
what are some ways to prevent enzymatic browning?
covering the food with water, or, as in the case of fruit, a sugar syrup
Blanching the food can also destroy the enzymes. Blanching occurs when food is immersed in boiling water for a short period of time and then plunged into cold water to stop the cooking process
