Raw milk quality of individual and collective expansion tanks of a dairy industry located in Rio Pomba, Minas Gerais, Brazil - a case study

Abstract

This study aimed to evaluate the microbiological and physico-chemical quality, and verify the occurrence of microbial growth inhibitors in raw milk maintained in expansion tanks of a dairy industry located in Rio Pomba, Minas Gerais, Brazil.. It was collected 36 samples of raw milk from 12 expansion tanks in three replicates and determined the count of mesophilic aerobic, psychrotrophic and proteolytic psychrotrophic microorganisms. It was also determined the somatic cell count, the occurrence of pus and inhibitors of microbial growth in milk samples. Moreover, it was determined physico-chemical composition of milk. It was found that 80.0% of samples were in disagreement with standards established by Normative Instruction n.º51, once mesophilic microorganisms and somatic cells counts were above 7,5 x 10⁵, in addition to the presence of pus and microbial growth inhibitors substances. Also, the count of psychrotrophic and proteolytic psychrotrophic microorganisms were high, which compromises production of dairy products such as cheese, UHT milk, among others. However, we found no irregularities in levels of protein, fat, lactose, and total solids. Therefore, the implementation of good agricultural practices during handling, storage and transportation of raw milk to the dairy industry is necessary in order to minimize financial losses during production and to obtain better quality and safety of dairy products.