Produção de polvilho azedo em escala piloto a partir de bactérias do ácido láctico e leveduras.

Abstract

Sour cassava starch was produced in a pilot-scale fermentation process with selected starter cultures to standardize the final product. The selected isolates were Lactobacillus plantarum Lp3, which presented antagonistic and acidification activities, and Pichia scutulata Ps9, which showed amylolytic capacity. Single and mixed cultures of the selected isolates and also commercial baker’s yeast were tested in the fermentation of cassava starch as four starter cultures: L. plantarum, L. plantarum with P. scutulata, L. plantarum with commercial baker’s yeast and commercial baker’s yeast. The acidity gradually increased during fermentation. The counts of L. plantarum remained close to 7 log10 CFU/mL, in both single and mixed cultures, and the yeasts showed a decrease in their counts throughout the process. The total titratable acidity was higher for the sour cassava starches obtained with L. plantarum in a single culture (3.02 ± 0.21) and in association with P. scutulata (3.06 ± 0.44). The final products were in agreement with the physicochemical and microbiological parameters. When compared to the cassava starch, the sour cassava starches obtained with L. plantarum and L. plantarum with P. scutulata resulted in the reduction of saturated fat of 3.6% and 8.1%, respectively, and an increase of unsaturated fat of approximately 2.3 times, the proportion of oleic, linoleic and linolenic acids also increased. Compared to the commercial sweet and sour cassava starches, the sour cassava starches obtained with the starter cultures led to a higher content of unsaturated fatty acids. Acids, alcohols, aldehydes, ketones, esters, ether, phenol and hydrocarbons were among the volatile compounds identified in the samples. The sour cassava starch obtained with the mixed culture had a greater variety and greater proportion of volatile compounds than the cassava starch and the sour cassava starch obtained with the single culture. Among these volatile compounds, there were compounds which are characterized by imparting aroma to foods such as the 4-hexyl2,5-dihydro-2,5-dioxo-3-furanacetic acid (2.84%) and the geranyl isovalerate (0.81%). Although the presence of the yeast did not cause a significant change in acidity nor the expansion capacity, it helped in the production of desirable aromatic compounds contributing to the characteristic aroma of sour cassava starch. Thus, it is suggested that L. plantarum in association with P. scutulata shows potential to be applied in the industrial production of sour cassava starch.