Food-Grade Cultivation of Saccharomyces cerevisiae from Potato Waste

Abstract

Potato waste is generated in a high amount, stably over the year, by operators capable of recovering it. Currently, it is valorized as feed, bioethanol, or biogas. This work explores another avenue to increase the valorization of this waste: the production of yeast production to serve as fodder or single-cell protein. First, potatoes were deconstructed into fermentable sugars by acid hydrolysis using food-grade techniques. Then, after pH adjustment, Saccharomyces cerevisiae was inoculated, and cell growth was monitored. For optimization purposes, this procedure was led over a large range of temperature (90–120 °C) and operation time (30–120 min), for a 1/2 solid/liquid ratio. Response surfaces methodology allowed to achieve a maximum sugar release (44.4 g/L) for 99 min under 103 °C. Then, a numerical model combining biological performances and factory process planning was used to derive process productivity (the best compromise between sugar release and cell growth). Maximal productivity (82.8 gYeast/w/L in batch mode, 110 gYeast/w/L in fed-batch mode) was achieved for 103 min under 94 °C. Furthermore, the process’s robustness was confirmed by a sensibility analysis. Finally, as the proposed procedure preserves the food-grade quality of the substrate, the produced yeast can be used as food or feed.