Processing of vegetables which are frozen before canning and sterilizing

摘要

The improved firmness obtained in frozen vegetables by a two-step blanch prior to freezing consisting essentially of a lower temperature blanch to activate pectin methyl esterase in the vegetable to increase firmness followed by a higher temperature blanch to inactivate enzymes thereby to prevent the development of off flavors during frozen storage is retained when the frozen vegetables are canned and heat sterilized. The firming effect is accentuated when the food grade calcium salt is added or when a food grade acid is added to reduce the pH below 4.5. The greatest firming effect is obtained when both a food grade acid and a food grade calcium salt are added.