Caracterização genética e fisiológica de Saccharomyces cerevisiae selvagens para produção cervejeira: desenvolvimento de um scale up indusrial

Abstract

The challenges of using wild yeasts in the brewing industry are considerable. Still, they are justified by the wealth of biodiversity and the growing demand for beers with improved sensory properties and distinct aromas. This study aimed to genetically and physiologically characterize wild Saccharomyces cerevisiae for brewing and obtain an industrial scale-up. Biomolecular techniques were used to genetically characterize the 5 indigenous Saccharomyces, nominally LBGA-01, LBGA-287, LBGA-288, LBGA-Hv8 and LBGA-Hb1. Maximum likelihood phylogenetic relationships were inferred by sequencing the amplified product from the ITS regions. Growth was evaluated on different carbon sources, as well as in the presence of stressors such as ethanol and iso-α-acids from hops. The strains were also characterized for POF production, flocculation capacity, foam formation, and resistance to osmotic pressure. Micro fermentations were conducted to investigate fermentation kinetics, apparent attenuation, ethanol production, and pH reduction. The strains showed physiological characteristics similar to commercial standards. Strategically, the LBGA-01, LBGA-287, and LBGA-Hv-8 strains were used for small-scale beer production (9 liters). Physical-chemical, HPLC, and GC analyses showed similarities and differences in the levels of nitrogen uptake (FAN), alcohol yield, by-product profile, and volatiles. The analysis of gene expression (qPCR) allowed a better understanding of the main determinant genes for the fermentation process. The results of the sensory evaluations were treated employing Principal Component Analysis (PCA) and contributed to the formation of the mixed inoculum between strain LBGA-287 and the commercial standard WB06™. Finally, the industrial scale-up phase allowed to obtaining of beers with aromatic and organoleptic characteristics of great interest to the brewing industry.