Food Science Terms


substances that turn universal indicator aperture shades of red.  They form salts when they react with a base. Found in foods: citric acid in citrus fruits, tartaric acid in cream of tartar, ascorbic acid (vitamin C) in fruits and vegetables, amino acids in proteins.


substances that neutralise acids. Alkali is also called a base e.g. Acid plus base = salt plus water. Sodium bicarbonate is an alkali in cooking.

Amino acids: 

molecules made up from carbon, hydrogen, oxygen and nitrogen with linked phosphorus and sulphur.

Ambient temperature:

Normal room temperature around 18⁰C- 20⁰C


An additive, which prevents oxidative rancidity of fats in foods.

Biological value:

(BV)  The value a protein food gives to the human body to enable growth and repair in the body.


A process which occurs when sucrose is heated and changes in colour

from white to golden brown giving characteristic flavour change.


A substance made up from carbon, hydrogen and oxygen. Carbohydrate is a macronutrient, the major source of energy for the body.


A catalyst is a substance that increases the speed of a chemical reaction without being consumed by the reaction.


 An irreversible process where proteins denature, changing from a soluble to an insoluble structure. As proteins coagulate they form crosslinks between themselves which’ holds’ or ’sets’ mixtures e.g. Raw eggs are coagulated by heat.


The insoluble protein in connective tissue, tendons bones and skin of

animals and fish. It is converted to the soluble protein substance gelatine in the presence of

moist heat and therefore increases the tenderness of meat.


 a homogenous mixture made up of two phases one dispersed in another e.g. milk is a fat-in-water colloid.


Part of an experiment used to compare results


An alteration in the structure and shape of protein caused by heat, acid alkali or

mechanical action. It is an irreversible process.


the changed state of starch (dextrin) caused by application of dry heat.


Soluble compounds formed by the breakdown of starch by heat, enzymes or acids.  Dextrins are formed in the presence of dry heat when bread is toasted.

Emulsifying Agents:

Substances which help water and oily liquids to be uniformly dispersed together creating an emulsion.


is a natural emulsifying agent found in egg yolks that helps stablise emulsions e.g. when making mayonnaise.


 A mixture of two immiscible liquids which can be stabilised or separate out on standing.


Natural protein substances which control other bio-chemical reactions e.g. Ascorbic acid oxidase controls loss of vitamin C in cut fruits.


Chemical breakdown of sugars by the action of yeast or bacteria or enzymes e.g. grape juice to wine, soya milk to tofu, cream to créme fraiche.  Products labelled as cultured or soured.


Formed when gas or air is introduced in quantity into a liquid or semi-liquid. Masses of bubbles are a characteristic. Egg white meringue, ice-cream and whisked sponge mixture are all examples.


The addition of nutrients to manufactured foods to provide an increased intake and replace nutrients lost during processing. White flour is fortified with iron and Vitamin B (thiamin and niacin).


A process that occurs when starch is mixed with a liquid and heated. The

starch swells, absorbs and bursts as it gradually thickens the liquid. Used in sauce making.


A mixture of the low biological value (LBV)proteins glutenin and gliadin that combine to form gluten when water is added to flour. Dough is formed with characteristic elasticity.  Gluten is denatured by heat and loses elasticity. Gluten sets, holding the risen structure of baked goods.


Substances used in food manufacturing to stabilize emulsions. Gums are hydrocolloids. Guar Gum See: Xanthan gum


 A process where milk (a colloid) is forced through fine nozzles to break

fat globules into fine droplets which are dispersed and remain dispersed throughout the milk.  No cream line occurs on standing or during shelf life.


Substances used in food processing, such as glycerol, which inhibit the loss of moisture from manufactured baked products. Humectants hold the water and prevent crystallization of sugar in confectionery and growth of ice crystals in frozen foods.


The treatment of oils by the addition of hydrogen under pressure which attaches to unsaturated double bonds in the oil (lipid). Was used in margarine manufacture to firm up the oil to become a spreadable fat. Now other methods are used.


substance that absorbs moisture from the air.  Sugars are hygroscopic.


 Colloidal structures that hold water.e.g. Gums


A liquid that changes colour to indicate acid or alkaline.

Invert sugar:

Produced by the hydrolysis of sucrose. Used in the manufacture of sweets as it prevents the crystallization of sucrose.

Lactic acid:

produced by the fermentation of carbohydrate lactose in milk. Give characteristic flavour to fermented dairy products.


 Milk sugar. A disaccharide formed from one unit of glucose and one unit of galactose.


An emulsifier naturally present in egg yolk. Helpful in making fresh mayonnaise and in cakes.  Used as an emulsifier in manufactured foods.


the nutrients in the diet measured in g.  Protein, carbohydrate and fat.

Maillard reaction:

 A browning reaction, NOT due to enzymes, which occurs due to a reaction between carbohydrates and proteins during cooking at high temperatures. Responsible for meaty flavour and colour on the surface of roasted meat , and browning on baked goods where protein and carbohydrates are mixed e.g. cakes


A (a fungi) compressed to form Quorn.  An ingredient that provides a good source of protein.


the nutrients in the diet measured in milligrams or micrograms, vitamins and minerals


A mixture is a substance made by combining two or more different materials in such a way that no chemical reaction occurs. A mixture can usually be separated back into its original components. Some examples of mixtures are a tossed salad or salt water.


 A deep red tissue pigment that is responsible for the colour of meat. It holds

oxygen in the muscles and enables them to function

Oxalic acid:

A substance present in rhubarb leaves and spinach, which is poisonous if consumed in large amounts.


the chemical reaction of a product with oxygen which might adversely affect flavour texture or colour of a product and limit shelf life.

Oxidative rancidity:

Occurs in unsaturated fats and oils. The reaction is initiated by the

presence of some metals, ultra-violet light and high temperatures.


The heat process used to make safe food e.g. milk or fruit juices.  Helps to prolonging the keeping quality of products by heating to destroy harmful bacteria.

pH is the level of acid or alkaline concentration of a substance, on a scale of 0-14 where 0 is very acidic and 14 is very alkaline


Capacity of a fat to melt over a range of temperatures enabling it to be firm, spreadable or melt. 


A complex polysaccharide, formed by some plants. It forms gels in water and is used

in the setting of jam.


Long chains of amino acids used to form proteins.


Formed from long chains of monosaccharide units. Called starch, they are insoluble in cold water.


 Term used to describe the chemical structure of fatty acids with more than one double bond.

Pre-gelatinised starch:

Starches heat treated to speed up end cooking time e.g. quick cook pasta, quick cook rice, easy blend flour for sauces without lumps.


Substances added to some processed foods to prevent spoilage.


Live micro-organisms which are added to foods and thought to restore the

microbial balance in the intestine.


Essential constituents of all cells.  Composed of carbon, hydrogen, oxygen, nitrogen phosphorus and sulphur.


see mycoprotein


A chemical change in fats caused by oxidation or hydrolysis. It causes ‘off’ flavours to


Retrogradation (of starch):

the opposite of gelatinisation. The starch undergoes a colloidal

change and contracts due to the loss of water. Stabilizers are used in processed foods to

reduce retrogradation.

Saturated solutions:

A solution that has absorbed as much of a solute as possible at a given temperature. E.g. sugar in water


the liquid stage of a colloid e.g. gelatin  when cooled a sol become a gel.


a homogeneous mixture of two phases – the solute and the solvent.


Substances which absorb water and are often used as thickening agents or to keep an emulsion stable.


A long chain polysaccharide composed from units of glucose.


mixture with two phases solvent and solute that eventually separates.


Refers to overcooked eggs custard, when the proteins shrink as they coagulate and

squeezes out watery liquid ( Seen as holes in the baked custard).  Also degrading of a set white sauce as it shrinks.


The thickness of a liquid or a mixture related to flow, such as a sauce.

Xanthan gum:

Polysaccharide produced by bacterial fermentation and used as a thickening

agent to form gels and increase viscosity. Used to replace gluten in gluten free flour to achieve acceptable baked products.


Microbe and biological raising agent. Bakers yeast has the technical name, Saccharomyces Cerevisciae. A source of vitamin B. Ferments to produce carbon dioxide if it has food, moisture, warmth and time.


sugar-free sweetener