Preservatives are substances added to food to prolong their shelf life. They prevent or reduce bacterial or fungal growth. Examples of preservatives are salt, nitrites, sulphur dioxide, propionate, and benzoate.
Antioxidants are added to oils and fats to stop them going rancid because of oxidative damage. They may also be added to fruits and vegetables. Examples of antioxidants are butylated hydroxytoluene, ascorbate, and a-tocopherol.
Emulsifying, stabilizing, and thickening agents are added to food to improve consistency, stability, and homogeneity of the product. Examples are monoglycerides and diglycerides, agar, and various vegetable gums.
Colouring agents are added to make food and drink look more appealing. Some are synthetic, for example tartrazine and erythrosine, while others are natural, for example carotene and annatto.
Flavouring agents and enhancers are used to create or improve the flavour of a particular foodstuff. This is the biggest group of additives. Some flavours are natural, for example plant extracts and resins, while others are synthetic, for example esters and ketones. The most widely used flavour enhancer is monosodium glutamate.
Artificial sweeteners are use to sweeten food or drink without adding calories. Examples of artificial sweeteners are saccharin, aspartame, and acesulfame K.
Nutrients are considered as food additives only in the USA, and not in other countries. The group includes vitamins, minerals, and essential amino acids.
Miscellaneous additives, including acidity regulators used to adjust the pH of fruit juices, for example; anticaking agents (for example, magnesium stearate, silicon dioxide) which are added to sugar or salt so that they flow freely; anti-foaming agents to stop liquids foaming; flour treatment agents which improve baking properties; glazing agents, like shellac and carnauba wax; propellants; and raising agents.
The use of food additives has increased enormously in the past thirty years, especially as the Western diet now comprises many processed foods. This means that we are exposed to a variety of food additives. Are all of these additives necessary? And what are their effects on our bodies?
Some additives clearly serve an important function. Preservatives help to prevent food from spoiling and enable processed food to be stored for much longer. They reduce the likelihood of bacterial contamination in the food we eat. Sodium nitrite is added to cured meat, for example, to prevent the growth of organisms like Clostridium botulinum, which causes severe toxicity, botulism (see pp. 249-51). Preservatives also reduce chemical degradation and so allow food to have a longer shelf life. Other additives may also have a beneficial function, for example artificial sweeteners reduce the sugar intake of people who suffer from diabetes or obesity.
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