Microbial contamination in industrial tofu/Contaminacao microbiana em tofu industrial

• Published in: Ciência rural 2017-03, Vol.47 (3)
• Main Authors: Ribeiro, Thais Teresa Brandao Cavalheiro, Costa, Gessica, da Costa, Marisa
• Format: Article
• Language: English
• ISSN: 0103-8478
• DOI: 10.1590/0103-8478cr20160234

This study aimed to evaluate the microbiological quality of tofu sold in supermarkets in Porto Alegre/Brazil. Bacteria counts were performed for Bacillus cereus, mesophilic, coliforms and Staphylococcus coagulase positive and negative. The presence of Listeria sp. was also evaluated. Two different brands of tofu (A and B) were collected, one lot per month, for six months. Five samples from each lot were analyzed. All lots presented mesophilic aerobic counts above 4.3 x [10.sup.5]CFU [g.sup.-1]. Four of the six lots from brand A and all lots from brand B showed E. coli and/or Staphylococcus coagulase positive counts above the Brazilian law accepted limits. The Staphylococcus coagulase negative counts were higher than those of coagulase positive in all lots. In all lots where Staphylococcus coagulase positive counts were above the legal limit, there were counts of coagulase negative above [10.sup.4]CFU [g.sup.-1]. B. cereus and Listeria sp. were not found in either brand. The majority of lots of brand A and all lots of brand B were unsuitable for human consumption. Our results showed that there are problems in tofu manufacturing in both industries analyzed. There is a need of improvement on its microbial quality to avoid problems of food-borne illness, and finally the need of a better control by the Brazilian inspection services. Key words: soy cheese, mesophile, coliforms, Staphylococcus, coagulase. Este estudo teve como objetivo avaliar a qualidade microbiologica de queijo tofu comercializados em um supermercado da cidade de Porto Alegre, RS. Foram realizadas contagens de Bacillus cereus, bacterias mesofilas, coliformes, Staphylococcus coagulase positive e negativo e, a pesquisa de Listeria sp. Foi realizada a coleta de duas diferentes marcas (A e B), com um lote por mes, durante seis meses; sendo analisadas cinco amostras de cada lote. Todos os lotes apresentaram contagens de mesofilos aerobios acima de 4,3 x [10.sup.5] UFC [g.sup.-1]. Quatro dos seis lotes da marca A e todos os lotes da marca B apresentaram contagens de E. coli e/ou Staphylococcus coagulase positive acima do permitido pela legislacao vigente. As contagens de Staphylococcus coagulase negativos foram superiores as contagens dos coagulase positivos em todos os lotes. Nos lotes em que foram encontradas contagens fora do padrao estabelecido para os Staphylococcus coagulase positivos, havia contagens dos coagulase negativos acima de [10.sup.4] UFC [g.sup.-1]. Nao foram isolados B. cereus e Lis