Food Waste as an Alternative Feed Stock for Lactic Acid Fermentation: A Process Study and Industrial Perspective

The demand for lactic acid (LA) continues to rise across food, pharmaceutical, and cosmetic industries, driving interest in cost‑effective fermentative production methods. Conventional feedstocks have been widely used, but growing emphasis on sustainability has shifted research toward renewable sources such as food waste (FW) and lignocellulosic biomass. In this study, restaurant FW collected from Pune, India was characterized for carbohydrates, proteins, fats, and trace elements, and subjected to an optimized pretreatment process involving slurry preparation, oil removal, amylolytic, pectinolytic, and proteolytic enzyme hydrolysis. The removal of fibrous material through solid–liquid separation, followed by the reduction of excess water via vacuum evaporation yielded consistent and process-ready substrate having 94.1% solids separation efficiency and 90.17% sugar extraction efficiency. Final feedstock yielded had 43.2% solids and 24.23% fermentable sugar concentration by weight. yielded lactic acid titer of 91 g/L and productivity of 1.9 g/L·h, surpassing previously reported FW and other renewable feed stock fermentation results. The concentrated FW feedstock developed through pretreatment we optimized always supports high lactic acid titer and demonstrates durability and transportability, similar to molasses and grain in few respects. The FW‑derived substrate with high solid and sugar concentration can be handled within industrial supply chains, ensuring storage and distribution. This functional equivalence combined with the added sustainability benefits; the FW can be positioned as a robust and renewable alternative for large‑scale lactic acid production. The process we developed, demonstrates strong scalability and commercial feasibility, though challenges remain in managing FW heterogeneity and logistics of collection and transportation.