Isolamento e identificação molecular de bactérias lácticas e leveduras envolvidas no processo fermentativo da mandioca para produção de tucupi e avaliação higiênico sanitário

Abstract

Cassava is a substrate to produce various fermented foods that are consumed in Brazil, Asia and Africa. Cassava stands out as an important agricultural product, since it constitutes the food base for families in the north and northeast of Brazil. The tucupi, a fermented sauce and subjected to cooking, is obtained after the spontaneous fermentation of the manipueira, a liquid residue from the pressing of the grated manioc mass. The tucupi is considered an ingredient very appreciated and used in the cuisine of Parana and northern Maranhão. Studies on the characterization profile of tucupi quality and identity are scarce. Among the main characteristics of this product are the yellow color, low pH value, high total acidity, low protein content and total and free cyanide. The objective of this study was to characterize the microbiota present in the cassava fermentation process to produce tucupi. For this, the samples were obtained from the production of tucupi and the final product were submitted to the isolation of lactic bacteria and yeasts in culture media MRS and YM, respectively, and the identification of the species by molecular techniques, by Fragment Length Polymorphism Restriction (RFLP) for BAL and GTG5 fingerprinting Restriction Fragment Length PCR (PCR) for yeasts. The isolates not identified by these molecular techniques mentioned above were submitted to sequencing the 16S region of the rRNA gene for BAL and D1 / D2 region of the major subunit of the rRNA gene for yeast. In addition, all samples were submitted to physical-chemical analysis and sanitary hygiene conditions. Lactic bacteria and yeasts were isolated in all samples with counts varying from 1.80 to 7.25 log10 CFU / mL and 2.15 to 8.11 log10 CFU / mL, respectively. Lactobacillus fermentum was the most isolated species in samples of tucupi production, in which it was possible to follow the whole process, followed by L. plantarum. Other species were found less frequently, L. acidophilus and L. parabuchneri. Candida ethanolica and Yarrowia lipolytica were the most isolated yeast species during tucupi production, followed by Candida tropicalis, Pichia scutulata, Pichia exigua, Candida humilis and Wickerhamomuces anomalus, which appeared less frequently. The pH values ranged from 3.10 to 4.29, and acidity from 0.2 g to 1.1 g lactic acid / 100 mL, classifying tucupi as a low pH and high acidity food. The tucupi samples showed total coliform counts in the samples of cassava mass, at the beginning of the fermentation and in the pure tucupi, and thermotolerant coliforms in only two samples (beginning of the fermentation and pure tucupi), were negative for Salmonella sp and unsatisfactory for the presence of B. cereus s. s., noting that the isolates of B. cereus sensu stricto were evaluated for the detection of toxin - producing genes and all showed a toxigenic potential. Thus, it is suggested that the production of tucupi should be performed under better hygienic-sanitary conditions