functional properties of food - term 2 Flashcards
what are the functional properties of food?
how ingredients behave during preparation and cooking. And how they affect the finished food product in terms of how it looks, tastes, and feels.
- how ingredients behave during preparation and cooking
- how they affect the finished product in terms of how it looks, tastes and feels
what are the factors that influence functional properties?
- oxygen or pH level
- temperature
- mechanical action agitation
- acidity
- enzyme
- addition of other ingredients.
what are the macro nutrients that are commonly found in food
- Protein
- Carbohydrates
- Lipids
what is protein
A macronutrient
One of the main nutrients found in foods are meat, eggs, wheat and dairy
Composed of amino acids which are joined together by peptide bonds
structure of proteins
- fibourous protein
- globular protein
- amino acid
- peptide bond
what are the functional properties of protein
denaturation
coagulation
gelation, foaming
browning and gluten
formation of proteins
what are dipeptides and polypeptides:
When two amino acids form a bond between each other, a dipeptide is formed.
A polypeptide is created when many amino acids are joined together.
A typical protein may contain 500 or more amino acids, joined together by peptide bonds.
what is protein folding
Each protein has its own specific number and sequence of amino acids.
The chains of amino acids making up the structure are also held together by bonds, often between sulfur atoms.
The molecule’s shape is important as it often determines the protein’s function.
what is denaturation
Denaturation is the change in the structure of protein molecules.
The process results in the unfolding of the protein’s structure.
It is a partially reversible change
what are factors that contribute to denaturation
- heat
- salts
- pH (acidity)
- mechanical action
what is an example of denaturation
when an egg white is whisked it incorporates air to form a foam
what is coagulation
Coagulation follows denaturation
The heat causes egg proteins to unfold from their coiled state and form a solid, stable network.
This change is irreversible.
what is an example of coagulation
For example, when egg white is cooked it changes colour and becomes firmer (sets)
what is flour strength
Products that require short (non-elastic) textures, such as biscuits and cakes, use flours with lower protein contents.
The lower the amount of gluten, the more crumbly and less elastic the final dough will be.
The amount of kneading is also important, as the more a dough is kneaded, the more gluten formation occurs
what is gelation
Gelatine is a protein that is extracted from collagen, present in animal connective tissue.
When it is mixed with warm water, the gelatine protein molecules start to unwind.
On cooling, a stable, solid network is formed, trapping the liquid.
In some cases gelation is reversible
what is an example of gelation
jelly, lollies and fruit based spreads
what is foaming
A foam results when gas (air) is dispersed (spread) through a liquid.
An example of this is egg whites which have an excellent ability to foam when denatured by agitation (beating).
Beaters create spaces for the air to enter and then becomes trapped in the stretched de natured proteins
what is an example of foaming
whipped cream
what ways can browning occour
- Enzymatic browning
- Myoglobin browning
- Millard reaction
what is enzymatic browning
Enzymes are proteins that speed up chemical reactions.
This effects light coloured fruits e.g. potatoes, bananas, apples and avocado.
Enzymatic browning is reduced by covering foods, coating in citric acid and submerging in water
what is myoglobin browning
blood protein myoglobin in meat heats and denatures changes color from pink to brown.
Oxygen in the air can cause fresh meat to brown. Oxidation iron in the meat exposed to oxygen (air)
what is Millard reaction (browning)
refers to denatured proteins recombining with sugars under the presence of dry heat.
This results in the brown color and flavour
