food science

Caramelisation

A process which occurs when sucrose is heated and changes in colour from white to brown.

Coagulation

A process that involves the denaturation of proteins; changing from a soluble to an insoluble structure.

Cook-Chill

A method of food preparation in which the food is cooked then rapidly chilled and stored below 5°C, thus increasing the keeping quality of the product for a short time.

Denaturation

An alteration in the structure of protein caused by heat, acid, alkali, or mechanical action. It is an irreversible process.

Dextrinisation

Starch turns brown in the presence of dry heat when bread is toasted.

Fermentation

The chemical breakdown of sugars by the action of yeast or bacteria.

Foams

Formed when gas is mixed into a liquid (e.g. air whisked into egg white).

Gelatinisation

A process that occurs when starch is mixed with a liquid and heated; the starch thickens the liquid.

Gluten

A mixture of the proteins glutenin and gliadin which provide structure and hold gas during the rising of bread.

Homogenisation

A process where pasteurised milk is passed through fine sieves to break the fat globules into fine droplets which are dispersed throughout the milk.

Hydrogenation

The conversion of oils to solid fats by the addition of hydrogen to the unsaturated double bonds.

Maillard reaction

A non-enzymic browning reaction which occurs as a result of heating during cooking and processing, but also occurs in some stored products such as dried milk.

Pasteurisation

The process of prolonging the keeping quality of products such as milk by heating to destroy harmful bacteria.

Plasticity

The capacity of a fat to spread.

Peptide bond

A link between amino acids used in the formation of dipeptides, polypeptides, and proteins.

Preservatives

Substances added to some processed foods to prevent spoilage.

Rancidity

A chemical change caused by oxidation or hydrolysis. It causes 'off' flavours to develop.

Syneresis

Usually refers to eggs; if overcooked, the proteins shrink as they coagulate and separate from the watery liquid.