Valorization of Fruit Pomaces for Glycosidic Enzymes Production via Solid State Fermentation

Background Agro-industrial waste represents an efficient and affordable substrate for microbial enzyme production; as an underutilized agricultural and food processing by-product, usage of Agro-industrial waste as a substrate for enzyme production fits within the framework of the circular bioeconomy by supporting waste valorization and environmental sustainability. This research evaluated the effective valorization of fruit-based agro-wastes (pomegranate, mango, orange, and grape pomace) for microbial production of glycosidic enzymes (amylase, xylanase, pectinase) using 14 microbial strains under solid-state fermentation conditions. Results For the 14 strains studied, Candida guilliermondii NRRL Y-2075 resulted in the highest reported amylase activity (4344.67 U/gds) when using pomegranate pomace. A response surface methodology was used with a central composite design model to optimize key parameters affecting amylase production for solid state fermentation: pH, inoculum size, incubation temperature and time. The optimum pH, size of inoculum, incubation temperature and incubation time were 5.6, 12.2%, 30.7°C and 24 hours, respectively, which resulted in a validated amylase activity of 4838.23 U/gds. The one-factor-at-a-time optimization revealed that the addition of external carbon, nitrogen, amino acids, or metal ions reduced C. guilliermondii amylase production given the richness of pomegranate pomace as a fermentation medium. Conclusion This study shows that fruit pomaces, especially pomegranate, can be used as a sole medium for glycosidic enzyme production, providing both efficiency and sustainability, emphasizing the relevance to industrial bioprocesses.