Metaproteômica como ferramenta tecnológica para otimização dos parâmetros de fermentação do milho para formulação de pasta alimentícia

Abstract

In most developing countries, maize products are often what alleviate hunger and guarantee the livelihood of the population. Fermentation is a processing medium used to soften the corn kernel, improve flavor and digestibility, and some fermented corn products are used in the belief that they have functional properties. Maize dough, obtained by fermentation, has already been reported as having a probiotic and nutraceutical effect, however, other studies discourage its consumption, justifying it by the load and diversity of microorganisms that develop during fermentation. With the aim of studying the functional profile and looking for likely ways to optimize maize dough, a recreation of the spontaneous fermentation of corn was performed, and the formulated dough was subjected to metaproteomics analysis. A total of 53977 peptides were recovered and identified, of which more than 60% were associated with the substrate, 6% with fungi, and 34% with bacteria. Metaproteomics revealed a probable association between Actinobacteria and starch degradation enzymes in the matrix. Proteobacteria (pathogenic majority) and Firmicutes (probiotic part) coexisted and multiplied in equal proportion until the end, allied to this, the high count of mesophiles(213 x 106 CFU/g) and the timid reduction of the pH (4.42) suggested a food product not completely safe. As a way to optimize the process, the maize was autoclaved at 121oC for 20 min for enzymatic inactivation and elimination of microorganisms, and then it was inoculated with Pediococcus acidilati. Untreated maize was also inoculated. The performance of the strain both in pre-treated maize (T+I) and in untreated maize (nT+I) was considered excellent, since, in the first 24 hours, the pH values, 4.2 for nT+I samples and 4.41 for T+I samples were at levels considered safe and decreased with fermentation time. The strong correlation between the fermentation parameters when P.acidilati was used for maize inoculation, opens possibilities for the application of optimization models towards the fast, safe, and industrial production of maize dough. Indeed, metaproteomics, as culture-free and protein-based technique, allows the rapid analysis of the microbiota and the identification of active microorganisms, with the advantage of displaying and correlating the microbial profile with functionality, and are well indicated to study fermented foods quickly and concisely, demonstrating effective methods for optimization