Food preservatives are the substance that are used in the process of treating and handling of fruits to stop or greatly slow down spoilage (loss of quality, edibility or nutritive value) caused or accelerated by micro-organisms. It also includes processes to inhibit natural ageing and discoloration that can occur during food preparation such as the enzymatic browning reaction in apples which causes browning when apples are cut. Minimally processed fruits and vegetables are preserved by use of a flavonoid. Cut and peeled fruits or vegetables are sprayed or dipped in a solution containing a flavonoid and an anti-oxidant such as ascorbic acid, erythorbic acid or alpha lipoic acid. Juices are also preserved by the addition of a flavonoid and ascorbic acid if it is not already present.
The fresh fruit preservative preserves the texture, flavour, appearance, crispness, and color of the fresh fruit, particularly the exposed skin of the fresh fruit.
Sugar as fruit preservative
Sugar is used to preserve fruits, either in syrup with fruit such as apples, pears, peaches, apricots, plums or in crystallized form where the preserved material is cooked in sugar to the point of crystallisation and the resultant product is then stored dry. This method is used for the skins of citrus fruit (candied peel),and ginger. A modification of this process produces glacé fruit such as glacé cherries where the fruit is preserved in sugar but is then extracted from the syrup and sold, the preservation being maintained by the sugar content of the fruit and the superficial coating of syrup.
Sodium benzoate is a preservative, bacteriostatic and fungistatic under acidic conditions. It is used most prevalently in acidic foods such as jams and fruit juices. It is found naturally in cranberries, prunes, plums, cinnamon, ripe cloves, and apples. Concentration as a preservative is limited by the FDA to 0.1% by weight.
Sulphur di oxide
It is used as a preservative for dried fruits.
Citric acid is an organic (carbon based) acid found in nearly all citrus fruits, particularly lemons, limes, and grapefruits. It is widely used as a flavoring agent, preservative, and cleaning agent. Citric acid is produced commercially by the fermentation of sugar by several species of mold. As a flavoring agent, it can help produce both a tartness [caused by the production of hydrogen ions (H+)] and sweetness (the result of the manner in which citric acid molecules "fit" into "sweet" receptors on our tongues.
How to select
The fruit preservative should be selected depending upon the fruits to be preserved, the processing specifications and the desired end product i.e juice or dried fruit of pulp, etc. Check the expiry date before buying.
· The use of fruit preservative is to stop spoilage and discoloration in fruits.
· Fruit preservatives are added in preparation of jams, jellies, purees, juices.
How to store
Store fruit preservatives in an air tight container and keep it in the refrigerator.
· Though natural preservatives may be added to fruits while processing, one should avoid an excess use of artificial preservatives as their repeated use have shown to pose health risk.