Preservatives are used to prevent bacteria, yeast and mould growth, preserve colour and flavour and keep food from going bad by preventing oxidation.
It can be hard to avoid preservatives as they can be found in almost any type of food or drink.
There are many natural preservatives such as salt, vinegar and sugar, but most of the preservatives used by food manufacturers are synthetic.
In a study done in Turkey, potassium sorbate was found to be genotoxic to the human peripheral blood lymphocytes in vitro (ie: causes damage to the DNA).
Sodium Benzoate (211) is used in carbonated drinks, oral medications, mouthwashes and added to acidic foods such as pickles, fish and oyster sauces, salad dressings, jams and fruit juices to enhance their flavour.
Even though sodium benzoate is found naturally in cranberries, plums, prunes, apples, cloves and cinnamon, it does not play the role of a preservative in these fruits and spices.
Sodium benzoate has anti-fungal and anti-bacterial properties. It works by entering the individual cells in the food and increasing the overall acidity of the food, thus creating an environment in which microbes and fungi cannot grow and spread.
When mixed with vitamin C, sodium benzoate forms benzene, a known carcinogen. The rate at which benzene is formed is affected by exposure to light and heat, as well as the time spent on the shelf from production to consumption.
Some studies have shown that sodium benzoate along with artificial food colourings may increase hyperactive behaviour in some children.
Sulphites inhibit bacterial growth, reduce spoilage, prevent browning of fresh food and help preserve medication.
Sulphites release sulphur dioxide, which is the active component that helps preserve food and medication.
According to The Australasian Society of Clinical Immunology and Allergy (ASCIA), sulphites can cause allergy and hay fever like reactions, wheezing in asthmatics, occasionally hives and very rarely severe, life-threatening anaphylactic reaction.
Recently, propionates are also permitted in cheese, fruit and vegetable products.
Very few people realise they are affected by this preservative as most people only notice a difference if they switch to preservative free bread.
Reported side effects include migraine, headaches, stomach upsets, skin rashes, nasal congestion, depression, tiredness, irritability and restlessness.
Bakers who keep their baking equipment clean and mould-free by wiping with vinegar daily, do not need to use propionates as mould inhibitor because a freshly baked loaf of bread does not contain any mould.
However, in large scale, commercial baking factories, hot loaves of bread are commonly put in plastic bags and this predispose to mould formation.
Sodium Nitrate (250) and Sodium Nitrite (251) are used in processed meat such as bacon, ham, sausages, hot dogs, luncheon meats, cured meats and smoked fish to preserve the meats and inhibit the growth of bacteria that causes botulism.
They are also used as a colour fixative to give meat the bright red colour and makes old, dead meats appear fresh and appetising.
When used for curing, nitrates react with the meat tissues to form nitrites. Nitrites can react with amines in meats to form nitrosamines, a class of potent carcinogens found in cigarette smoke.
Food Standards Australia New Zealand restrict food manufacturers from putting these preservatives in baby foods but not on foods typically consumed by many children such as hot dogs and luncheon meat.
Infants are very susceptible to nitrate toxicity as they can develop methaemoglobinemia or “blue baby syndrome.” Nitrates may convert to nitrites in the digestive tract. Nitrites can combine with haemoglobin to form methaemoglobin which lacks the ability to carry oxygen in the blood.
So, are these preservatives safe?