Evaluation of beer residual yeast as a substrate for the biotechnological process of hyaluronic acid production.

The search for waste reuse is essential to promote sustainability and avoid environmental impacts. The brewing industry, responsible for producing billions of liters of beer, uses yeast as one of its main inputs. It is responsible for the fermentation process, which is discarded after a few cycles of use due to loss of efficiency. In this context, this study aims to characterize yeast from beer production and investigate its potential use as a substrate for the fermentation process, aiming to produce hyaluronic acid. The residual yeast was characterized in terms of acidity, moisture, ash, total proteins, and lipids, subsequently used as a substrate for the production of hyaluronic acid using the bacterium Streptococcus zooepidemicus as a microorganism. The residual yeast showed a high protein content of 41.69%, and its use increased the production of hyaluronic acid by 58% compared to a conventional synthetic substrate. The yield in relation to biomass, Y_{AH, X} (g/g) was 0.250, which was higher than conventional yeast. The supplementation of mineral salts to the culture medium containing the residual brewer's yeast disfavored the production of hyaluronic acid, possibly due to the inhibition or death he microorganism responsible for fermentation and consequent production of HA. The results indicated the potential of applying residual brewer's yeast in biotechnological processes, contributing to the valorization of this residue.