Inativação microbiana e leite cru refrigerado pelo método de termo-sonicação

Abstract

Considering the high milk consumption and its importance in the diet, alternative technologieshave been studied in order to help the already existing in regards to microbial inactivation. The present study aimed to verify the efficiency of microbial inactivation through thermal-sonication in refrigerated raw milk, with further quantification of Enterobacteria, Coliformsat 35ºC and Standard plate count. The refrigerated raw milk samples were acquired fromrural producer. The samples were treated in a jacket glass Beaker, which was inside an ultrasonic bath containing a thermostatic bath as a heat source; the analysis were conducted before and after the thermo-sonication treatment. The work was characterized as afull factorial designof three levels (0, 10 and 20 minutes; 15, 35 and 55ºC) and two factors (time and temperature), totalizing nine experiments. The obtained results showed that there were no statistical differences between theEntero bacteria count of refrigerated raw milk and thermo-sonicated milk, except for treatment F (35ºC/20 minutes), that exhibited a significantly higher count in comparison to other treatment conditions, and suchresult did not fit the count limit of Normative Instructionn°76 of the Ministry of Agriculture, Livestock and Food Supply. However, treatment regimens I, G and H (all executed at 55ºC), regardless of the time, had acount within the limit established by current legislation, but these treatments had no statistical meaning when compared to the other treatments performed at this research. The results of the rapid tests for Standard plate countand Coliforms at 35ºC exceed the established limit by current legislation as well, before and after thethermo-sonicationtreatment.