Uses and examples

Packaged foods and drinks must state their contents by law. Until 1875, there were few effective controls on the contents or quality of food and drink on sale to the public. In the early nineteenth century, some of the commonly used substances added to food were meant to deceive the public.

To whiten bread, for example, bakers sometimes added alum (K₂SO₄.Al₂(SO₄)₃.24H₂O) and chalk to the flour, while mashed potatoes, plaster of Paris (calcium sulphate), pipe clay and even sawdust could be added to increase the weight of their loaves. Rye flour or dried powdered beans could be used to replace wheat flour and the sour taste of stale flour could be disguised with ammonium carbonate. Brewers too, often added mixtures of bitter substances, some containing poisons such as strychnine, to 'improve' the taste of the beer and save on the cost of hops.

By the beginning of the nineteenth century the use of such substances in manufactured foods and drinks was so common that town dwellers had begun to develop a taste for adulterated foods and drinks; white bread and bitter beer were in great demand. By the middle of the century, some legislation was in place - but the ability to enforce any such legislation required suitable analytical methods to identify the problem and then enforce the legal requirements. Today, analytical and legal controls in the EU and much of the rest of the world mean that food additives have to be pure and used at safe levels.

Typical reasons for analysing food products, raw materials and ingredients, include the following. These provide the basis for the examples covered in KT10:

• determining composition and checking for contaminants
• verifying authenticity and detecting adulteration
• surveillance and enforcement
• assessing suitability for purpose
• supporting product development and product formulation
• analysing flavour and flavour changes
• researching the chemistry and behaviour of food materials.

The examples that are given do not necessarily fit neatly into these categories - they usually overlap considerably and this reflects the reality of the situation. For instance, there have been examples of food adulteration that have led to contamination and serious safety problems.

Read the introduction to Section 4 and Sections 4.1 to 4.2 of KT10 (pages 83-94) to find out more about uses and examples of food analysis.

The following SAQs will help you to test your understanding of some of the applications of food analysis.