Microbiological Quality of Commercial Tempeh in The Netherlands

Abstract

A survey of the microbiological quality of commercial tempeh was done in The Netherlands. A total of 110 samples were examined. Most (98%) of the samples had an aerobic plate count above 107 CFU/g. Numbers of Enterobacteriaceae exceeded 105 CFU/g in 67% of the samples, whereas numbers of lactic acid bacteria exceeded 107 CFU/g in 81% of the samples. Staphylococcus aureus was found in 13%, Bacillus cereus in 11% and Escherichia coli in 3% of the samples at levels of 105 CFU/g. Yersinia enterocolitica was found in six samples, whereas Salmonella was absent in 25 g of all the samples examined. Many (69%) of the samples had a yeast count above 105 CFU/g. Trichosporon beigelii was the most frequent yeast species. Besides Rhizopus oryzae and Rizopus oligosporus, which obviously represent the mold species responsible for the fermentation, Mucor indicus was often associated with the mycoflora of the tempeh. The reasons for the poor microbiological quality are discussed and some recommendations are proposed.