Estudo da produção de ácido lático por bioprocesso utilizando soro de leite como matéria-prima

Abstract

Lactic acid is an organic compound that has great industrial importance due to its various applications already consolidated in the market and it is considered a safe compound and approved by the American Food and Drug Administration (FDA). The production of lactic acid can be carried out through chemical synthesis and by biotechnological route, with the availability of the pure isomers of this compound a determining factor in choosing the way of obtaining it. The chemical route produces a racemic mixture that interferes with the physical and chemical properties of the final product. The biotechnological route is seen as promising, considering that some species of microorganisms are capable of generating optically pure isomers and it is possible to use renewable sources as a substrate, in which it is possible to reduce the cost of the process. A possible raw material that can be used is whey, waste from the dairy industry, abundant, cheap and renewable. There are few reports in the literature on the production of lactic acid by Lactobacillus plantarum using whey as a raw material. In this context, the present study evaluated the production of lactic acid by biotechnological route in bench-scale, using two strains of the species Lactobacillus plantarum, specifically LAB07 and LAB14, isolated from artisanal cheese and pepper sauce, respectively, and deproteinated whey as carbon source. The age of inoculum culture, in which the strains were grown in isolation (16 h, 20 h and 24 h), temperature (30 °C, 37 °C and 45 °C), and rotation (100 rpm, 150 rpm and 200 rpm) were the parameters evaluated to conduct the experiments in an orbital shaker, using an inoculum concentration of 10% (v/v). The temperature was the operating condition that most influenced the bioprocess, especially when it was carried out using the LAB14 strain at 45 °C, as the acid production was very low compared to the other temperatures evaluated. The most favorable conditions for the production of the acid of interest were an inoculum culture aged 16 hours, a rotation of 100 rpm for both strains and a temperature of 37 °C for LAB07 and 30 °C for LAB14, obtaining a concentration of acid at the end of the fermentation of 11,89 g/L and 10,27 g/L, lactic acid productivity of 0,41 g/L.h and 0,30 g/L.h, and a biomass production of 1,74 g/L and 1,76 g/L for LAB07 and LAB14, respectively. In this context, the deproteinated whey and the evaluated strains of the species Lactobacillus plantarum were favorable to the production of lactic acid, even though they have low cell growth in the selected culture medium.