Microbial ecology and food safety of minas artisanal cheese from Araxá and Canastra, Minas Gerais, Brazil: from raw milk to ripened product

Abstract

Minas Artisanal Cheese (QMA) is a traditional Brazilian raw-milk cheese of high cultural and economic relevance in the state of Minas Gerais, particularly in the regions of Araxá and Canastra, whose safety and sensory identity are intrinsically associated with its autochthonous microbiota and traditional manufacturing practices. Considering the use of unpasteurized milk and the central role of microbial communities in determining product quality and typicity, this dissertation aimed to evaluate the microbiological safety and characterize the microbial ecology of QMA from both regions throughout ripening. Raw milk (n = 30), pingo (n = 30), and cheese samples (n = 180), collected at six ripening times (1–56 days) from 30 farms, were subjected to PCR for the detection of pathogens of public health relevance and to 16S rRNA gene sequencing for microbial community profiling. Listeria monocytogenes, Campylobacter spp., and Leptospira spp. were not detected; Staphylococcus aureus occurred sporadically at early ripening stages; and Salmonella spp. was identified as the main microbiological hazard, being predominantly detected in cheeses, suggesting contamination during processing. Microbial ecology analyses revealed diverse and dynamic communities, with a stable fermentative core dominated by Lactococcus and Streptococcus, as well as the persistence of genera associated with technological and potentially protective functions. In both regions, the structure and dynamics of microbial communities were shaped by the interaction among ripening time, farm-specific characteristics, and environmental and production conditions. Overall, the safety of QMA depends on strict hygienic control of Salmonella spp., while its regional identity is shaped, in Araxá, by a stable fermentative core dominated by Lactococcus and Streptococcus, influenced by pingo as an endogenous starter culture harboring Corynebacterium, Lactobacillus, and Lactiplantibacillus, together with environmental contributions of Flavobacterium and Lentilactobacillus, and, in Canastra, by the persistence of Lactococcus and Streptococcus throughout ripening, with Lactobacillus at lower relative abundance and farm-specific management practices supporting the maintenance of Acinetobacter and Lentilactobacillus.