Obtenção de extrato nitrogenado a partir de biomassa residual de levedura utilizando ultrassom para uso em processos fermentativos

Abstract

Yeast sludge is a byproduct generated in breweries in large quantities. The use of this by-product is small and is mainly used in animal feed. Yeast sludge has a high protein content and can be used as a source of low cost nutrients in biotechnological processes. The objective of this work was to obtain an extract rich in nitrogenous compounds of brewery yeast by optimizing through treatment with ultrasonic device and applying it in fermentative processes. In the extraction tests, the effects of ultrasonic wave amplitude, yeast / water ratio and extraction time on the nitrogen yield of the extracts were evaluated. Through the response surface methodology and the desirability function, the best treatment was defined as the extraction time 30 minutes, yeast / water ratio 55:45, and ultrasonic device wave amplitude of 70%. The extract obtained in the optimum extraction conditions was lyophilized for better practicality in its use. It was subsequently used in the alcoholic fermentation of water and glucose (120g / L), artificial and natural apple must. In the latter, three different strains of Saccharomyces cerevisiae (Bouquet, Aromatic, Reims Champagne) were isolated. The fermentation process was monitored by kinetics through the release of carbon dioxide, samples were taken after 1, 3, 6, 10, and 15 days of fermentation for cell counting and physicochemical analysis. In general, the addition of the extract resulted in an increase in the fermentation efficiency, reaching a higher fermentation speed in the first days, and a higher carbon dioxide release compared to the control samples, which were not added to the extract. It is also possible to observe that the higher the extract addition, the greater the efficiency in the fermentation kinetics. The ciders fermented with the different yeasts were sensorially evaluated for their odor quality, odor intensity and drink quality and it was verified that there was no alteration in the sensory characteristics of the drink, being the quality of the drink not harmed.