Lipolytic psychrotrophic microorganisms in dairy products during shelf life

Abstract

Psychrotrophics microorganisms are capable of multiplying at refrigeration temperature and can cause sensory changes in dairy products due to lipases and/or proteases production. This study aimed to analyze lipolytic psychrotrophic presence on high fat dairy products during its shelf life and also evaluate the physical-chemical changes caused by lipolysis. Ten brands of dairy products were analyzed four times during its shelf life, totaling 40 samples. Were performed the following analyzes: psychrotrophics microorganisms and lipolytic psychrotrophics counting, Bacillus spp presence, acidity, peroxide value, rancidity and lipolytic activity. Milk cream and cream cheese showed no counts of microorganisms psychrotrophic on analyzed samples. Two of three butter samples had psychrotrophic presence, however, just one of them showed a significant linear regression during the shelf life. Bacillus spp was found in a sample of butter 60 days after the production date, with a count of 100 CFU/g. There was no significant linear regression in acidity, peroxide and lipolytic activity during the period of analysis for any sample. Samples of milk products had appropriate microbiological quality and no signs of lipid oxidation during the regular shelf life.