Evaluation of storage time on parameters of quality of cooled raw milk

Abstract

The aim of this research was to evaluate the presence of psycrotrophics and psycrotrophics proteolytics bacteria and caseinmacropeptide (CMP) concentration in samples of cooled raw milk collected in the Southwestern region of the Goiás State, Brazil. The research was carried through in the Laboratório de Microbiologia of the Centro Federal de Educação Tecnológica de Rio Verde - GO, from January to February of 2008. To verify the concentration of CMP, the samples were sent to the laboratory of physical-chemistry of the Centro de Pesquisa em Alimentos of the Escola de Veterinária of the Universidade Federal de Goiás. The cooled raw milk samples were collected from ten expansion tanks located in properties of Southwestern region of Goiás. The collections were done in zero, 24, 48 and 72 hours of storage, obtaining a total of 40 samples. Then, they were carried through standard count in plates of viable psycrotrophics, psycrotrophics proteolytics, Pseudomonas spp., titratable acidity and CMP. The statistical analysis were developed at the R (2005) package using the procedures for regression models. The temperature of cooled raw milk during storage time did not influenced the evaluated parameters. The acidity was in accordance with Normative Instruction nº 51/2002. The average of count of psycrotrophics, psycrotrophics proteolytics and Pseudomonas spp. were high, which indicated lack of hygiene in the installations and utensils used in milking.