Emerging Sustainable Bioprocess for the Valorization of Agave Bagasse for Single-Cell Protein Production

Abstract

In this work, a food-compatible bioprocess was evaluated for the production of yeast single-cell protein from mezcal agave bagasse. Bagasse was enzymatically hydrolyzed at 10% (w/v) solids (pH 4.8, 50 °C, 24 h) using commercial enzymes. The resulting liquid was clarified by activated charcoal adsorption and filtration to obtain a hydrolysate suitable for submerged fermentation. Enzymatic hydrolysis released reducing sugars in the range of 11–17 g/L. Saccharomyces cerevisiae was cultivated on the clarified hydrolysate under submerged conditions using both flask-scale and 2 L stirred-tank bioreactor experiments. Trials were performed at flask scale with initial sugars at 8, 17, and 50 g/L, and at 2 L stirred-tank bioreactor scale with initial sugars at 20.68 g/L (R1) and 16.30 (R2) g/L. At the flask scale, final biomass concentrations increased with initial sugar level. Values reached 6.18 ± 0.27, 8.02 ± 0.55, and 9.28 ± 0.10 g/L, while crude protein remained below 10% (3.40 ± 0.15 to 8.69 ± 0.09 g/100 g dry weight). In contrast, bioreactor cultivation resulted in higher protein enrichment, with protein contents over 40% under both oxygen regimes (41.71 ± 0.47 to 45.80 ± 0.43 g/100 g dry weight). Overall, the findings support enzymatic hydrolysis coupled with controlled submerged fermentation as a scalable approach for valorizing agave bagasse into protein-enriched yeast biomass.