Optimizing Mycoprotein Production by Aspergillus oryzae Using Soy Whey as a Substrate

Soy whey, a by-product of soy processing, has shown promise as a substrate for mycoprotein production using <i>Aspergillus oryzae</i>. However, the low biomass concentration obtained necessitates optimization of cultivation conditions to enhance total protein production. In this study, we optimized substrate concentration (50%, 75%, and 100%), initial pH (unadjusted, 4, 5, and 6), and supplementation with 8 g/L ammonium sulfate, minerals (0.75 g/L MgSO₄·7H₂O, 1 g/L CaCl₂·H₂O and 3.5 g/L KH₂PO₄), or their combination to maximize biomass production. The results showed that adjusting the initial pH to 5 and adding ammonium sulfate and minerals increased biomass concentration by 169% from 1.82 g/L to 4.9 g/L in 100% soy whey. This optimized condition also slightly improved the protein content of the biomass from 53% <i>w</i>/<i>w</i> to 55.93% <i>w</i>/<i>w</i>. Additionally, cultivating <i>A. oryzae</i> under these optimized conditions significantly reduced soy whey's chemical oxygen demand from 8100 mg/L to 3267 mg/L, highlighting bioremediation potential. These findings suggest that the optimized conditions enhance the productivity of mycoprotein and also contribute to the sustainable management of soy whey waste, providing a combined benefit of nutrient recovery and wastewater treatment.