Quality of refrigerated, pasteurized and sterilized raw bovine milk from industries in vale do taquari – rs

Abstract

Milk is a food of animal origin, rich in nutrients and which, due to its nutritional properties, is a matrix for the growth of microorganisms. Physicochemical, microbiological and microbiome analysis in milk allow an accurate diagnosis of its quality. The aim of the present study was to evaluate the quality of refrigerated, pasteurized and sterilized raw milk from dairy industries in Vale do Taquari, Rio Grande do Sul, Brazil. Physicochemical and microbiological analyzes were performed, established by Brazilian legislation and the analysis of psychrotrophic microorganisms and total and thermotolerant coliforms. In addition, the microbiome was analyzed through high-throughput sequencing of the 16S rRNA gene. Both industries had somatic cell counts (SCC) above the limit established for refrigerated raw milk and psychrotrophic levels higher than those of mesophiles. Industry 1 presented acidity above the limit in the three types of milk, total bacterial count (TBC) and density for refrigerated raw milk and for pasteurized milk, respectively. The samples presented a wide diversity of genera, composed of psychrotolerant (Kurthia, Acinetobacter, Viridibacillus), biofilm formers (Pseudomonas), mastogenic (Streptococcus) and lactic acid (Lactococcus), in addition to genera considered harmful (Escherichia, Citrobacter, Aeromonas and Enterobacter).