► Class I preservatives or the natural preservatives such as salt, sugar, vinegar, syrup, spices, honey and edible oil; and
► Class II preservatives or the chemical preservatives such as benzoates, sorbates, nitrites and nitrates of sodium or potassium, sulfites, glutamates, glycerides and the like.
The food standards regulations require that not more than one class II preservative to be used on one particular food item.
Both, natural and chemical preservatives are categorized into 3 types:
► Antimicrobials that destroy or delay the growth of bacteria, yeast and molds. E.g. nitrites and nitrates prevent botulism in meat products. Sulfur dioxide prevents further degradation in fruits, wine and beer. Benzoates and sorbates are anti-fungals used in jams, salads, cheese and pickles.
► Anti-oxidants that slow or stop the breakdown of fats and oils in food that happens in the presence of oxygen(Oxidation) leading to rancidity. Examples of anti-oxidants include BHT, BHA, TBHQ, and propyl gallate.
► Anti-enzymatic preservatives that block the enzymatic processes such as ripening occurring in foodstuffs even after harvest. E.g. Erythorbic acid and citric acid stop the action of enzyme phenolase that leads to a brown color on the exposed surface of cut fruits or potato.
The following table shows the type of food preservatives used, the type of food products they are used in, and the permissible limits for their use.
|Food Preservative||Type of preservative||Type of food products||Maximum Permissible limit|
|Benzoates and sorbates||Antimicrobial||Pickles, margarine, fruit juices, jams, cheese||200 ppm (200 parts per million)|
|Propionates||Antimicrobial||Bakery products, cheese, fruits||0.32 percent|
|Sulfites and sulfur dioxide||Antimicrobial||Dry fruits and fruits, molasses, wine fried or frozen potatoes, prevent discoloration in fresh shrimp and lobster||200-300 ppm|
|Nitrites and nitrates||Antimicrobial||Meat products||100-120ppm|
|Propyl gallate||Antioxidant||Baked foods, meats||200 ppm|
|BHA (butylated hydroxyanisole) and BHT (butylated hydroxytoluene)||Antioxidants||Baked foods and snacks, meats, breakfast cereals, potato products||100 ppm for meat products, 50 ppm for breakfast cereals and potato products|
|Tert-Butylhydroquinone (TBHQ)||Antioxidant||Baked foods and snacks, meats||100 ppm|
|Erythorbic acid (iso-ascorbic acid) and citric acid||Antienzymatic||Soft drinks, juices, wine, and cured meats||200-350 ppm|