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Acidity |
Foods are grouped into low acid foods that have a pH above 4.5, and high acid foods that have a pH below 4.3 The acidity of foods influences the types of micro-organisms that can grow in them, and thus the methods of processing needed to destroy them or inhibit their growth. Increasing the acidity of foods preserves them (e.g. vinegar in pickles and sauces, or fermentation to produce lactic acid in yoghurt). Acidity contributes to the taste of a food. |
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Eating quality |
The colour, flavour, texture and appearance of a food. |
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Enzymes |
Proteins that catalyse biological reactions. There are many hundreds of different enzymes in foods, some of which cause spoilage (e.g. by causing foods to darken or develop a rancid flavour). |
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Food poisoning |
Caused by some types of bacteria from raw materials or poor personal hygiene by people who handle foods. It can result from eating a food that has a large number of live bacteria, or from poisons (toxins) produced by bacteria in the food. Some types of toxin can withstand heat and remain in the food after the micro-organisms have been destroyed. It can be prevented by correct processing good quality raw materials, training workers in correct food handling and by adopting quality assurance techniques. |
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Food spoilage |
Changes in flavour or texture, loss of colour, shrivelling and drying out or damage caused by pests and by micro-organisms. |
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Gluten |
A protein found in wheat that creates the structure of bakery products. |
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Micro-organisms |
Minute creatures that cannot be seen until they are present in vast numbers (e.g. a spot of mould on bread). There are four basic groups: yeasts, moulds (or fungi) bacteria and viruses. Within each group, there are hundreds of different types. Some are safe and are used in processing, but others cause food spoilage or food poisoning. In general yeasts prefer more acidic wet foods (e.g. fruit products), bacteria prefer less acidic wet foods (e.g. meat, fish, milk) and moulds are able to tolerate dry foods better than the other types, (e.g. cereals or nuts). |
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Packaging |
Protects foods after production until they reach the consumer. The main hazards to foods are damage due to crushing or impact, environmental factors (moisture, air, heat, light etc.), damage caused by pests and micro-organisms, chemical and enzymic changes within the food (e.g. staling, rancidity, browning, etc.), theft, adulteration and tampering with products. Apackage should also keep the contents together without leakage until they are used. |
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Pathogens |
Food poisoning micro-organisms. |
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Pectin |
A substance found in fruits that forms the gel in jams. |
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Rancidity |
Unpleasant flavours in fats and oils caused by enzymes, micro-organisms or when they are broken down by heat or light. |
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Shelf life |
The time before a processed food begins to spoil. |
