ost foods undergo a certain degree of processing. Even those foods considered whole, such as fruits and vegetables may have been processed to wash and prepare the foods for market. While a limited and slowly dwindling number of foods are presented at market in a minimally processed form, the requirement for raw ingredients by the consumer has fallen in recent decades. The result is that the vast majority of foods available are now processed and in a more ‘ready-to-eat’ condition. This causes problems for food manufacturers because such foods tend to spoil quickly due to the underlying chemical composition of the ingredients. There are a number of considerations that must be addresses during the processing steps such as the shelf-life, palatability, appearance and texture. In many cases, the manufacturers rely on a number of additives to modify the final product. While some of these additives are natural compounds, others can be synthetic chemicals.
Refrigeration and the use of heat to denature enzymes is used extensively to limit spoilage, and these techniques are successful in many cases. However, some additives can also help prevent spoilage. Benzoic acid (E210), propanoic acid (E280), sorbic acid (E200) and sodium metabisulphate (E223) are all commonly used preservatives. These have similar effects to salt and vinegar that have been used for centuries to limit food spoilage, and work by creating an environment in which microorganisms cannot grow. Problem microorganisms can include yeast, moulds and bacteria. Most modern preservatives have serial numbers in the 200s. Spoilage can also occur when foods become rancid due to oxidation, and this is a particular concern for foods containing polyunsaturated fatty acids. In this case, antioxidants such as butylated hydroxyl anisol (E320), butylated hydroxyl toluene (E321), propyl gallate (E310) and tocopherols (E306-309) are used. These antioxidants also preserve the content of some vitamins.
However, as well as spoilage, there are other considerations that must be addresses during the processing of foods, such as the palatability, appearance and texture. Emulsifiers such as monoglycerides and diglycerides of fatty acids (E471) and lecithin (E332) are used to allow oil, water and stabilisers to mix to prevent separation in products, such as with mayonnaise. Flavours such as monosodium glutamate (E621) and sodium inosinate (E631) tend to be controversial because they alter the taste properties of the foods artificially. Many artificial flavours are added, particularly in fast food preparations, that are designed to physically addict the consumer to the food. Thickeners are also used to increase palatability, and these include guar gum ((E421), locust bean gum (E410), pectin (E440) and carboxymethyl-cellulose (E466). These tend to be natural fibres that can decrease the glycaemic effect of food because of their ability to increase the viscosity of food.
Colours in foods can be lost during processing, and there is a pressure on the manufacturers to increase the visual appearance of some foods and to ensure batch conformity. Natural colours include beetroot red (E162), carbon black (E156), chlorophyll (E140) and β-carotene (E160). Egg yolks are often artificially yellowed with β-carotene through incorporation of carotenoid rich foods in the diet of the hens. In addition, some artificial colours such as tartrazine (E102), brown FK (kipper brown; E154) and erythrosine (E127) are also used but these are more controversial due to some published evidence showing behavioural reactions in sensitive individuals. Most colours have serial numbers in the 100-200 range. Sometimes when colours are added to foods, solvents must accompany them to assure uptake to the foods. The only permitted solvent in glycerol (E422), which helps dissolve the colour prior to addition to the food.
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