Sulphur dioxide, bisulphites and sulphites: Sulphites, as a source of sulphur dioxide, has been extensively used as preservatives in foods for quite sometime now. They are effective, versatile and economical additives which are used as antimicrobials in the preservation of a number of food items viz. jam, jelly, marmalade, hit, hit pulp and juices, syrups and sherbets, alcoholic beverages, confectionery, dry hits and meat products. They are also used as bleaching agents in the refining of sugar as antimicrobial agents, to control enzymatic and non-enzymatic browning reactions in dehydrated hits and vegetables and to provide protection against oxidative reactions.