Foram analisadas microbiologicamente 100 amostras de carne bovina coletadas de supermercados na cidade de Barretos - SP. As amostras foram obtidas quando encontravam- se estocadas sob temperatura de -1 a 7°C. Na ocasião da amostragem 25 amostras de carne de primeira em pedaço foram pesadas em duas porções de 100 g, sendo uma delas moída na hora e a outra embrulhada separadamente. O mesmo procedimento foi obedecido para as 25 amostras de carne de segunda qualidade. Realizou-se contagem padrão em placas e isolamento de Yersinia enterocolitica para as 100 amostras coletadas. Verificou-se que nenhuma amostra de carne ultrapassou o limite de 3,0 x 10⁶ (nível máximo estabelecido pela Legislação Brasileira). No entanto, 16% das amostras de carne de primeira moída e 24% das amostras de carne moída de segunda mostraram contagens acima do nível permitido. As porcentagens de isolamento de Yersinia enterocolitica nas amostras foram respectivamente: carne de primeira em pedaço e segunda (8 e 12%); carne moída de primeira e segunda (12 e 16%). Ficou estabelecido que a moagem contribui significativamente para o aumento da contaminação da carne e também, com baixa evidência, pode cooperar para a disseminação de Y. enterocolitica em carne bovina.

A study of the effect of grinding on the microbiological quality of ground beef was conducted in Brazil, in the town of Barretos - São Paulo State. A hundred samples of beef of two different Brazilian cuts were collected. One cut (which we called "first cut") comprised: round and rumps sirloin, toin and rib. The other one (which we called "second cut") comprised: brisket, square chuck, shank, plate and flank. The samples were collected in a period of six months following the same standard procedures which stablished that whole part should be stored at the temperature range part should be stored at the temperature range and ground at the sampling moment. As an indication of microbiological quality, the total plate count test was performed on the whole and ground parts of the same sample and also the presence of the pathogenic bacteria Yersinia enterocolitica was investigated in all samples. The results of this study have shown that neither cuts of the whole beef had plate counts above 3.0 x 10⁶ UFC/g (maximum allowed by Brazilian Regulations). The presence of Yersinia enterocolitica was detected in 8% of the "first cut" and in 12% of the "second cut" in the whole parts. These levels have increased to 12% and 16% for the first and "second cuts" respectively after grinding procedures. These results indicated that the grounding process can contribute to a significant increase infection in only ground beef which indicates that new methods of cleaning up the grinding machine should be adopted so the problem could be overcome or at least reduced.