Food additives and fortification: the functions of additives (preservatives, antioxidants, colours, flavourings, emulsifiers and stabilisers, sweeteners); the E-number system and the control of additives; and the fortification and enrichment of foods, including the reasons for adding nutrients and examples of fortified foods.

A 6-mark answer needs each additive named with what it does and why, two marks each.

Preservatives extend the shelf life of food by slowing or stopping the growth of micro-organisms. This keeps the food safe and saleable for longer and reduces waste; examples include the nitrites used in cured meats and sulphur dioxide in dried fruit.

Antioxidants slow oxidation. They stop fats and oils going rancid and stop cut fruit and vegetables browning, by reacting with oxygen before it can damage the food. Vitamin C (ascorbic acid) and vitamin E are common natural antioxidants.

Emulsifiers allow ingredients that do not normally mix, such as oil and water, to form a stable emulsion. They have a hydrophilic and a hydrophobic end, so they coat droplets and keep them suspended, improving texture and stopping products splitting; lecithin is an example.

Markers reward two points for each additive: (1 and 2) preservatives slow microbial growth to extend shelf life, (3 and 4) antioxidants slow oxidation to prevent rancidity and browning, and (5 and 6) emulsifiers hold immiscible ingredients together for a stable texture.

A 4-mark answer needs the definition plus two clear public-health reasons.

Fortification is the deliberate addition of one or more nutrients to a food, either to replace nutrients lost in processing (enrichment) or to add nutrients that were not there before, to improve the nutritional value of the food and the diet.

Reasons include: to address a known deficiency in the population, for example adding folic acid or B vitamins and iron to flour and breakfast cereals, or vitamin D to spreads; to restore nutrients lost during processing, such as the vitamins removed when white flour is milled; and to help specific groups meet their needs, such as adding vitamins to infant formula.

Markers reward (1) fortification is adding nutrients to a food, (2) to improve nutritional value or replace losses, and (3 to 4) two valid reasons such as tackling a population deficiency and restoring nutrients lost in processing, with an example.