Studies on Fermentative Processing of Apple Fruit

Part XII. Maceration of ammonia-added apple pulp in cider-making

Abstract

The pH value of fresh apple pulp was adjusted from 3.0 to 3.8, 4.4 and 5.0 by addition of ammonia to increase activity and stability of malic enzyme of apple fruit during "maceration" treatment in cider-making. Decrease in malic acid content of the juice during maceration became appreciably larger by neutralization of the pulp; especially pH values above 4 caused remarkable decrease. Besides, pectin and tannin contents of the juice decreased more largely; amounts of lactic and succinic acid in the juice slightly increased; and yield of the pressed juice slightly increased, by high-pH-maceration. Alcholic fermentation of the juice obtained was rapid and ethanol content of the resulted cider was considerably high. About 85-95% of the added ammonia was assimilated by yeast and removed from the must during fermentation. Addition of an adequate amount of ammonia in the maceration treatment gives a fine cider which has an adequate acidity and no abnormal constituent or flavour.