Preparation and evaluation of an animal feed byproduct produced by solid-state fermentation of apple pomace

Abstract

After solid-state fermentation (SSF) with different yeasts and removal of ethanol, dried apple pomace powders were found to be enriched in crude protein (3 times), fat (1.5–2.0 times) and vitamin C (2 times). There was also an increased content of minerals (Zn, Cu, Mn and Fe), crude fibre and ash. The products were free from aflatoxin. However, soluble protein content increased slightly while sugar content was reduced. The colour, Ca, Mg and energy values of the dried apple pomace remained almost unaffected. Among the yeasts, Candida gave the highest crude protein, Saccharomyces better soluble proteins, Torula the lowest fat content with comparable total sugar but different acid contents. The yield of dried apple pomace varied from 54 to 65% with dehydration (4.35:1) and rehydration ratios (1:4.20 to 1:4.60) quite comparable to the dried, unfermented apple pomace. It is concluded that apple pomace used concomitantly for ethanol production by fermentation with Saccharomyces and dried after ethanol removal could be used profitably as an animal feed.