MOLKE ALS SUBSTRAT UND PROZESSWASSER FUR DIE PRODUKTION VON SCP

Abstract

The aim of our study was to develop a technique allowing the production of yeast protein from agricultural substrates by avoiding waste water. The product should be of high biological quality and harmless in terms of toxicity. Using Saccharomyces cerevisiae acidified whey, to which enzymatically hydrolysed wheat flour was added, was fermented in a 20 m’ plant in a two step procedure: 1. Conversion of the lactose in whey into a mixture of lactic acid/ammonium-lactate by lactic acid fermentation. 2. Fermentation of the suspension at high cell densities in the fermenter by deep jet aeration. Using a semi-continuous feeding system the RNS content in the yeast solids fell from 4,07 to 2,37 % within 21 h. In technical experiments carried out simultaneously on the reduction of the RNS content using heat shock treatment a yeast was obtained which contained 3,05 % RNS in the solids. After drying of the fermented material, the crude protein (less ammonia) and the ash contents in the final product accounted for 50 and 5,7 %, respectively. Residual humidity was 6,2 % (drying tower) and 8 % (roller-drying).