MICROBIOLOGICAL EVALUATION OF YOGURT PRODUCED COMMERCIALLY IN ONTARIO

Abstract

One hundred and fifty-two commercially-produced yogurts were subjected to microbiological examination for lactobacillus/streptococcus ratio, staphylococcus count, coliform count, enterococcus count, yeast and mold count, and psychrotrophic count. These yogurts were produced by 13 different manufacturers and sold in Ontario. The desired 1:1 ratio of lactobacillus to streptococcus was found in 15.1% of the samples. Streptococci were predominant in 40.8% and lactobacilli in 44.1% of the samples. Staphylococci were found in 27.6% of the samples, enterococci in 36.2%, and coliform in 13.8%. Yeast counts in excess of 1000/g were noted in 26.3% of the samples and mold counts >10/g in 17.8% of the samples. Psychrotrophs at levels >1000/g were found in 11.8% of the yogurts examined.