Utilização de Saccharomyces cerevisiae em co-cultura com bactérias do ácido láctico para produção de polvilho azedo

Abstract

Brazil has been the second largest producer of cassava in the world. In the food industry, cassava is used in the elaboration of various products and by-products such as: biscuits, cheese bread, among others. These products have as main ingredient the sour cassava starch, which is obtained by means of fermented cassava starch. The main production stage of the sour cassava starch is fermentation. The predominant microbial population during fermentation comprises lactic acid bacteria (LAB) and yeasts, which interact during the fermentation process. The objective of this work was to evaluate the efficiency of pure and mixed starter cultures during the fermentation of cassava starch and the quality of the final sour cassava starch produced. Lactic acid bacteria Lactobacillus plantarum and Lactobacillus brevis, isolated from the natural microbiota from the fermentation of sour starch were tested as pure starter cultures and in co-culture with Saccharomyces cerevisiae UFMG-A1007. Changes in pH, total titratable acidity (TTA) and viability of the fermentation samples, and the physical-chemical characteristics (acidity, pH, expansion, moisture, ash and starch) of the final products obtained were evaluated. The microbiological quality of the sour cassava starch produced was also investigated. L. plantarum, L. brevis, and S. cerevisiae were isolated at counts of 7.83, 7.84, and 7.09 log10 CFU / g, respectively at the beginning of the fermentation of the sour cassava starch. These starter cultures produced pH values between 2.88 and 4.13 and ATT values between 0.41% and 2.11% at 28 days of fermentation. Samples collected during fermentation presented different behaviors (p <0.05), in relation to pH, ATT and viability of the microorganisms tested. However, the results obtained (ATT, pH, expansion, starch, ash and moisture) for the final products showed no significant difference (p> 0.05) between the different starter cultures studied, so that all products were considered as sour cassava starch. Microbiological analyzes indicated that all cultures provided safe products. S. cerevisiae and L. plantarum remained viable during the whole process, while L. brevis remained for only 14 days as a pure culture and for 28 days as a mixed culture. It suggests that S. cerevisiae plays a relevant role during fermentation, since it favors the presence of L. brevis in the fermentation process, enabling it to be present until the end of fermentation. The starter cultures using S. cerevisiae in association with LAB presented good fermentative performance and can be used to control and standardize the production process of the sour cassava starch by providing homogeneous and high quality products.