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In this study, the addition of Lactobacillus casei Zhang in the manufacture of Minas Frescal cheese was investigated. Minas Frescal cheeses supplemented with probiotic bacteria (Lactobacillus casei Zhang) were produced by enzymatic coagulation and direct acidification and were subjected to physicochemical (pH, proteolysis, lactic acid, and acetic acid), microbiological (probiotic and lactic bacteria counts), and rheological analyses (uniaxial compression and creep test), instrumental color determination (luminosity, yellow intensity, and red intensity) and sensory acceptance test. The addition of L. casei Zhang resulted in low pH values and high proteolysis indexes during storage (from 5.38 to 4.94 and 0.470 to 0.702, respectively). Additionally, the cheese protocol was not a hurdle for growth of L. casei Zhang, as the population reached 8.16 and 9.02 log cfu/g by means of the direct acidification and enzymatic coagulation protocol, respectively, after 21 d of refrigerated storage. The rheology data showed that all samples presented a more viscous-like behavior, which rigidity tended to decrease during storage and lower luminosity values were also observed. Increased consumer acceptance was observed for the control sample produced by direct acidification (7.8), whereas the cheeses containing L. casei Zhang presented lower values for all sensory attributes, especially flavor and overall liking (5.37 and 4.61 for enzymatic coagulation and 5.57 and 4.72 for direct acidification, respectively). Overall, the addition of L. casei Zhang led to changes in all parameters and affected negatively the sensory acceptance. The optimization of L. casei Zhang dosage during the manufacturing of probiotic Minas Frescal cheese should be performed.

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The gastrointestinal tract (GIT) is a dynamic microecosystem containing a diversified microbiota of about 500-1000 different microbial species. Humans depend on their intestinal microbiota to carry out vital functions, and thus, equilibrium among intestinal groups of microorganisms is essential. In this review article, the use of traditional and molecular methods is discussed for the characterization of the intestinal microbiota, as well as its interaction with probiotics and their effects on health. An improved knowledge on intestinal microbiota composition and diversity and how changes in this microecosystem can cause or are associated with diseases remains far from being completely understood. Therefore, a better understanding of the GIT microbial populations is crucial, which will certainly contribute to the development of new strategies for the prevention and/or treatment of several diseases. The manipulation of the GIT microbiota by probiotics consumption is an interesting approach to maintain and restore human health.

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