Artificial preservatives are chemical substances added to foods. These substances may be sprayed on the outside of a food, or added to foods in medications. The exact definition of an artificial preservative is problematic , however, as many artificial preservatives are in fact derivatives of natural compounds.
Most commonly chemical preservatives are derived from acids and their main preservative function is that they raise the acidity of foods which kills microorganisms. Artificial preservatives may be organic (derived from a living organism e.g. a plant) such as Benzoates, Propionates and Sorbates or inorganic (derived from non living things e.g. rocks) such as Sulfites (Sulphites) and Nitrites/Nitrates.
Artificial food preservatives are subdivided into antimicrobial agents, antioxidants and chelating agents.
Some people are particularly sensitive to preservatives; while others are much less sensitive. Unfortunately, you cannot be certain of how sensitive or tolerant you might be; unless you are specifically tested for those sensitivities.
Antimicrobial agents are added to foods to destroy bacteria or inhibit the growth of mold on food. This division includes Benzoates, sorbates, proprionates and nitrates. Although you may not wish to use these products in home food preservation, it is important to be aware of their uses and potential health implications. Amongst other considerations, this may help you to show the benefits of your own products.
Use of Nitrates
Nitrates are salts of nitrous acid, the most commonly used nitrate being sodium nitrate which is added to meat and smoked fish where it helps prevent the growth of bacteria such as Clostridium botulinum- the bacterium responsible for Botulism (as described in chapter 2) Another benefit attributed to sodium nitrate is due to the fact that it interacts with the myoglobin in meat which helps to give meat a more appealing dark red appearance.
Nitrates have some health implications which have made them less appealing as a food preservative. Nitrates are toxic in large quantities and may also lead to the production of nitrosamines which are potentially carcinogenic (cancer causing).
Benzoates are compounds based on benzoic acid, they are most frequently used in the preservation of soft drinks such as carbonated drinks and squashes, but are also found in products such as pickles, flour, toothpaste and medicines. The most commonly used benzoate is potassium benzoate - the potassium salt of benzoic acid, which inhibits the growth of mold, yeast and bacteria. Sodium benzoate is also very widely used as a food preservative in the preservation of fruit juices, pickles, salads, margarine, jams and jellies.
Possible health considerations-
When combined with ascorbic acid (vitamin C) benzoates can form benzenes which are known to be carcinogenic. Benzoates have also been suggested to effect hyperactivity in children.
Proprionates are compounds of proponic acid, they are most frequently used to prevent the formation of mold in baked goods. One of the most commonly used proprionate is Calcium proprionate used to inhibit the growth of mold on bread. Sodium proprionate is also widely used in the preservation of bread, chocolate, cheese and pastry.
Possible health considerations
The health effects of proprionates are cumulative and build up over a period of time – weeks to months. Health effects can range from symptoms of irritable bowel syndrome to nasal congestion, restlessness, difficulty sleeping and attention deficit disorders.
Sorbates are compounds based on sorbic acid, they are frequently used to prevent food decay in products such as bread, dairy products, salad, fruit products and smoked fish. Potassium sorbate is the most commonly used food preservative in the world.
Possible health considerations
Some people develop an allergy to sorbates which, among other symptoms, can present as stomach ache, altered bowel habits or as an itchy mouth, throat, eyes or skin. Sorbates have also been associated with the development of migraines and Potassium sorbate can cause raised potassium levels in the blood (hyperkalemia) in patients with kidney disease.
These are a group of artificial preservatives which help to prevent food spoilage by slowing down the reaction of food with oxygen in the atmosphere. Some antioxidants are natural including retinoids (vitamin A) and ascorbic acid (vitamin C) which is found in fruits and vegetables. Artificial antioxidants include butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) which are used in bakery products, fats and oils. Some antioxidant preservatives are also naturally present in foods as well as being artificially synthesized to add to foods such as Sulphites (also spelt sulfites). Both natural and artificial antioxidants are used to preserve a variety of foods including vegetable oils and spreads, nuts, cheese and bread.
Sulphites are a group of compounds consisting of charged molecules of sulphur combined with oxygen. Sulphites have a long history in food preservation as they occur naturally in most wines. Today the antioxidant, antimicrobial properties of sulphites serves a variety of functions in food preservation which help to preserve aspects of food such as taste and colour e.g. preserving the pink colour of meat and fish. The main sulphite preservatives include sodium suphite, sodium bisulphite, sodium metabisulphite, potassium bisulphite, potassium metabisulphite and sulphur dioxide. Sulphites are generally applied to foods in a dipping solution through a spray.
Sulphites can cause allergies and other health conditions The most common symptoms include shortness of breath, wheezing, coughing, increased symptoms of asthma as well as skin rashes and nausea. Ingestion of foods containing sulphites can be a particular problem for patients with asthma or those who are allergic to acetylsalicyclic acid or asprin.
Chelating agents are chemicals added to foods in order to bind metal ions such as iron, cobalt and copper which would otherwise exert detrimental effects on the colour, texture, aroma and colour of food. The most commonly used chelating agent is EDTA (Ethylenediametetra acetic acid) which helps to prevent colour deteriation. EDTA is used in soft fats such as in mayonnaise, spreadable fats and sauces where it helps keep these products from going rancid preserving their taste and flavour. EDTA also helps to protect foods from bacteria by removing the metal cofactors that the bacterial enzymes require to grow and is added to canned foods to eliminate any metal taste from the can.
EDTA is safe to health in the quantities used in foods. Side effects are generally only seen where EDTA is used as a medicine.