Production of Saccharomyces cerevisiae from agricultural and food processing wastes

Upcicling biowastes and residues from the agroindustry through the production of microorganisms used in the food industry could give rise to innovative circular practices. In this work, different agricultural and food processing wastes from the potato, wheat and tomato industries were studied as potential feedstocks to produce yeasts, using Saccharomyces cerevisiae as a model. After a first screening in conical flasks, tomato seeds, tomato filtration water, wheat bran and frozen potato peels-based media, supplemented with sucrose were selected for 3-L bioreactor trials. Some variability in the production was found according to the batch used. Aeration rate (0.5, 1.0 and 1.5 L/min), agitation speed (150, 300 and 600 rpm) and temperature (25 and 30 °C) did not affect the growth of S. cerevisiae in the 3-L bioreactor when frozen potato peels at 21.9 g dry matter/L supplemented with 10 g L−1 of sucrose was used as the growth medium. The population obtained by upscaling in a 90-L bioreactor (7.64 log cfu mL−1) was similar to that obtained in the 3-L bioreactor (7.76 log cfu mL−1); however, the maximum population was reached later. A commercial baker's yeast produced in this medium was used to make the bread, and although the color and hardness were significantly different, no differences were found at the consumer level. This work demonstrated that it is possible to produce a baker yeast from agricultural and food processing wastes without affecting its fermentation ability.