... expecially mechanical pupls, it is the most fittable bleaching agent in pulps.3, it is used in bleaching kaolin ... compound of thiourea and other sulphides5 it is used as reducing agent in chemical industry.6, sodium hrdrosulfite food additive grade ... is used in foodstuffs, as bleaching agent andpreservative in dried fruits , dried vegetable ,vermicelli, glucose, sugar ...