Caracterização microbiológica e físico-química do Queijo Minas Artesanal da região Serras da Ibitipoca, ao longo da maturação nos períodos seco e chuvoso

Abstract

Minas Gerais stands out for its cheese production, especially Minas Artisanal cheese (MAC), famous for reviving local historical traditions. This cheese is made from raw milk, pressed by hand and matured at room temperature. Natural variations in the milk, pingo (endogenous starter), and cheese result in unique characteristics distinct from each producing region. This study aims to characterise the physicochemical and microbiological quality of Minas Artisanal cheese from the Serras da Ibitipoca region. Water, milk, pingo and cheese samples were collected from six properties and analysed over 60 days of ripening during the rainy and dry seasons. In the rainy season, the water samples met the pH standards; this analysis was not carried out in the dry season. Free residual chlorine showed no significant difference (P>0.05) between the seasons. For the microbiological analyses of the water, there was no difference (P>0.05) between the averages of total and thermotolerant coliforms of the seasons. However, they were higher than required by legislation. In the analyses of somatic cell count (SCC), standard plate count (SPC), and total and thermotolerant coliforms analysed in the milk, there were no differences (P>0.05). On the other hand, Staphylococcus spp., coagulase-positive Staphylococcus and lactic acid bacteria (LAB) showed differences (P<0.05) between the seasons. The averages of the milk analyses showed significant differences (P<0.05) for fat, defatted dry extract (DDE), lactose, tritable acidity and pH. There were no differences (P>0.05) between the dry matter, moisture, protein and ash analyses. The pingo showed no differences (P > 0.05) for the salt, tritable acidity, total coliforms, thermotolerant coliforms, Staphylococcus spp. and coagulase-positive Staphylococcus and LAB analyses. In the analyses of the cheeses, there was a difference (P<0.05) between the ripening times in the rainy and dry seasons for total and thermotolerant coliforms. As for Staphylococcus spp. and coagulase-positive Staphylococcus, there was no difference (P>0.05) between the seasons, but there was between the times and the interaction. LAB was only analysed in the dry season, showing high counts in the cheeses up to 60 days of ripening. Salmonella spp. and Listeria monocytogenes were not identified in the cheese samples. Moisture, protein, water activity and weight showed differences (P<0.05) between the seasons and ripening time but not in the interaction (P>0.05). For fat, adhesiveness, chromatic coordinate a*, height and diameter, there was no difference between the seasons (P>0.05), but there was a difference (P<0.05) between the seasons and the interaction. The analyses of chlorides, luminosity, and the chromatic coordinate b* of the cheeses showed differences (P<0.05) between seasons, time and interaction. The extent and depth of proteolysis, cohesiveness, elasticity and ash did not show differences (P>0.05) between the seasons and the interaction. However, they did occur (P<0.05) throughout ripening. The pH of the cheeses showed a difference (P<0.05) between the seasons but did not occur over time and interactions (P>0.05). Chewiness only differed between seasons (P<0.05). There was also a difference in hardness in relation to time (P<0.05) but not in the interaction (P>0.05). The cheeses did not meet the 22-day ripening standards due to the high counts of coliforms at 30°C, 45°C and coagulase-positive Staphylococcus. Adopting Good Milking Practices (GMP) and Good Manufacturing Practices (GMP) during production and proper hygiene when keeping the cheeses during ripening can reduce contamination. It helps to ensure that the cheeses fulfil the legal requirements effectively.