BEER-SPOILAGE BACTERIA AND THEIR CONTROL WITH A PHOSPHORIC ACID – AMMONIUM PERSULFATE WASH

Abstract

Flavobacterium proteus, Acetobacter aceti, Acetobacter capsulatum, Pediococcus cerevisiae, and Lactobacillus pastorianus were isolated from contaminated yeast in certain Canadian breweries. F. proteus was most prevalent in ale yeast, while L. pastorianus and P. cerevisiae were most prevalent in lager yeast but the plant also affected the prevalence of the species.A phosphoric acid – ammonium persulfate wash was developed which has proved very effective in the breweries in which it has been used since 1960. Treatment time is very short (2 hours) and consequently a great saving in plant equipment and labor has resulted.The fermentative ability and viability of Saccharomyces cerevisiae is not affected nor is it killed even when it is treated with a phosphoric acid – ammonium persulfate wash that is six times as strong as the one recommended for use in the brewery.