Yeast nutrition and practical aspects during brewing fermentations

Abstract

The amounts of beer produced by a world spread brand mark and the competitiveness of this market drive consistent research programs in order to improve and make the brewing process more profitable. In this work, the nutritional aspects of yeast concerning needs and limitations during fermentation of very high gravity (VHG) worts were studied. Considering nutritional aspects of the brewing process, the yeast could be affected before pitching the wort or/and during the fermentations. Using as target yeast, yeast slurry collected from an industrial storage tank (where the yeast is stored between re-pitching, from industrial fermentation to a new one), several nutrients were tested to evaluate the feasibility of the nutritional yeast pre-treatment regarding to an improved fermentation performance during VHG wort fermentations. The yeast was firstly kept in contact with the nutrients in study (one or a combination of many) at the same conditions of temperature and steering as the industrial plant. The yeast was stored in those conditions during different periods followed by lab-scale fermentations with high stressful medium, i.e. high gravity wort to evaluate the fermentation performance. Linoleic acid and Tween 80 are nutrients that could be added just few hours before pitching the wort to the yeast storage tanks, inducing a positive effect on the extract consuming and viability of the cropped yeast. The addition of Mg2+, Ca2+, Zn2+, Cu2+, Fe2+ and K+ were also studied as yeast supplements on yeast storage tanks. Another type of nutrients, as ergosterol, biotin, and acetaldehyde were considered as a possibility of improving the fermentation ability of an industrial strain of S. cerevisiae.