The Chemistry and Technology of the Pretreatment and Preservation of Fruit and Vegetable Products with Sulfur Dioxide and Sulfites

Abstract

This chapter summarizes present status of knowledge in the chemistry and technology of the pretreatment and preservation with sulfur dioxide and sulfites, which is restricted to foods of plant origin. The theoretically available sulfur dioxide content and the usual range of SO2 content for various preparations have been shown. The chapter summarizes that sulfur dioxide added to fruit and vegetable products as liquid sulfur dioxide, as gaseous sulfur dioxide, as solution of sulfurous acid in water, or as dry or dissolved sulfites will exist as the undissociated sulfurous acid, as the free bisulfate ion, as the free sulfite ion, and as combined sulfur dioxide in the form of the hydroxysulfonates. The chapter discusses the preservative value of sulfur dioxide in fruit and vegetable products and other foods and beverages. The possibility of removing the sulfite added as a preservative by heating to decompose the combined sulfur dioxide and remove the free sulfur dioxide by volatilization has been investigated. In addition to desulfiting by physical methods, chemical methods ranging from treatment with oxidizing agents like hydrogen peroxide to addition of substances to combine with free sulfur dioxide such as acetaldehyde have been proposed for the treatment of juices and dried fruits. The chapter discusses sulfur dioxide as an inhibitor of enzymic and nonenzymic browning and the source and application off sulfur dioxide are mentioned. It discusses the uses of sulfur dioxide in fruit juices, syrups, concentrates and purées, wine and vinegar making, dehydrated and dried fruits and vegetables product, and in transportation and storage of grapes and other products.