COMPARISON OF COMBINATIONS OF DILUENTS AND MEDIA FOR ENUMERATING ZYGOSACCHAROMYCES-ROUXII IN INTERMEDIATE WATER ACTIVITY FOODS

Combinations of five diluents (0.1% peptone, 40 and 50% glucose, and 18 and 26% glycerol) and three enumeration media (tryptone glucose yeast extract, dichloran 18% glycerol and malt extract yeast extract 50% glucose (MY50G) agars) were evaluated for recovering a xerotolerant yeast, Zygosaccharomyces rouxii, from foods with intermediate water activity (a(w)). Combinations of 40% (a(w) 0.936) or 50% (a(w) 0.898) glucose diluent and MY50G agar (a(w) 0.890) were superior in recovering highest populations. The type of solute in the diluent, as well as a reduced a(w), influences efficiency of recovering viable cells.