Caracterização microbiológica de doce de leite, leite condensado e queijo minas padrão por metodologia clássica e padronização de multiplex para detecção de patógenos por PCR em tempo real

Abstract

Dairy products are food with exceptional nutritional value and are widely consumed by the population of various countries. However, they are also excellent culture medium for many micro-organisms, and is therefore liable to contamination by different microbiological agents which may lead to diseases manifested by the action of pathogens or their toxins. The attainment of safe food depends, among other factors, of the analysis methods used, which should provide fast and reliable results that allow the monitoring of microbiological safety of food, by the industry and the supervisory bodies and for this, alternative methods have been developed for detection and quantification of pathogens. The first objective of this study was to characterize microbiologically, by conventional method, samples of doce de leite, condensed milk and standard Minas cheese, produced in several states in Brazil. Standard count analysis were made in standard plate for mesophyll, yeasts and molds, coliforms at 30ºC and 45°C, Staphylococcus spp. coagulase positive and negative, as well as Salmonella sp. and Listeria monocytogenes. High standard counts on plates of mesophyll, yeasts and Staphylococcus spp. coagulase-negative were found in three products. The second objective was develop an alternative methodology to the classical, to produce faster and of high specificity results for detection of main pathogen contaminants of dairy products and transmitting of food diseases, using real-time PCR technique. A multiplex reaction was standardized for detection of Salmonella enterica var Thyphimurium and Staphylococcus aureus. This work will contribute to the rare literature on microbial contaminants of doce de leite, condensed milk and standard Minas cheese, providing scientific data to the academy, regulatory authorities and industry, envisioning the possibility of using alternative microbiological diagnosis methods instead of classic that provides faster and more sensitive results.