Alcohol production from whey permeate by yeast and by a thermophile strain

Abstract

This paper describes research efforts exploring the potential of alcoholic fermentation of whey permeate as a means of whey disposal and utilization in Switzerland. The effluent lactose content of unconcentrated permeate can be reduced to 2% of the original value by continuous fermentation with K. fragilis at a dilution rate affording a volumetric ethanol productivity of almost 5 g 1−1 hr−1. Although K. fragilis also completely ferments whey permeate concentrated twice in a batch mode with similar kinetic and stoichiometric performance, lactose uptake characteristics were quite deficient in continuous fermentation of permeates that were concentrated up to three times. Alcohol inhibition was shown to be one of the main impediments for fermenting concentrated whey. In view of the possibility to remove the inhibitor on-line by vacuum or stripping, fermentation at high temperatures by the thermophile T. ethanolicus was investigated. The preliminary results seem promising.