Abstract

Consumer preference for raw milk cheeses has increased in the past few years. This occurred partly due to their more diverse, enjoyable characteristics, but also due to claims that certain members of the autochthonous microbiota of milk can be beneficial to human health. These microorganisms can inhibit the growth of undesirable microorganisms and may also be used to establish a biogeographic identity for these products. The aim of this study was to assess the effect of a multi-strain probiotic preparation on the microbiological safety and composition of bacterial community of a traditional Brazilian raw milk cheese by means of culture dependent and methods and pyrosequencing. Probiotic enriched cheeses presented an average of 50% less sequence reads belonging to Enterobacteriaceae than control cheeses. Total and thermotolerant coliforms cell viability decreased throughout ripening in two seasons (summer and autumn), while in the winter the presence of these microorganisms was negligible since the beginning of ripening. Results obtained through culture dependent method did not correlate with culture independent method, which pointed to a relatively constant number of Enterobacteriaceae reads during ripening. Viable cells of coagulase positive Staphylococcus aureus stayed within legal limits in both groups of cheeses since the first day and decreased to zero at the 15^th day in probiotic enriched cheeses. Salmonella sp. and Listeria sp. were absent in both control and probiotic groups. Our results support that enriching raw milk cheeses with probiotic bacteria or other bioprotective bacteria may help mitigate off flavors produced by Enterobacteriaceae and result in safer products by inhibiting the growth of these microorganisms, while maintaining the microbial diversity that may be beneficial to sensory profiles and health-promoting characteristics. We also showed that this traditional cheese, if made under right the conditions, can meet legal parameters in much less than 60 days of ripening.

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