Continuous production of non-alcohol beer by immobilized yeast at low temperature

Summary A system for production of non-alcohol beer is described. A limited fermentation is carried out with immobilized cells ofSaccharomyces cerevisiae in a packed bed reactor. In the reactor, combined stress factors such as low temperature (2–4°C) and anaerobic conditions limit cell metabolism. Of the available sugars only a small amount of glucose is metabolized, resulting in low concentrations of ethanol (<0.08%). The absence of oxygen affects the redox balance of the yeast cell, and thus stimulates formation of esters and higher alcohols. Products are formed by reduction of wort aldehydes, as well as reduction of intracellular metabolites. Despite the stress conditions, biomass increases during prolonged production periods. In batch experiments,S. cerevisiae strain W34 grows at low temperatures and a mininum growth temperature of –2 °C was found, indicating that a further reduction of temperature during production will not inhibit growth. The characteristics of the system allow its use in very different applications. Potential applications of the immobilized system are discussed.This paper is dedicated to Professor Herman Jan Phaff in honor of his 50 years of active research which still continues.