Optimization of protein production from banana peel flour by Rhizopus oryzae through solid-state fermentation using response surface methodology

Banana peel is one of the wastes from bananas with a composition of 35-40% of the weight of fresh bananas. The use of banana peels as feed and food ingredients is very limited due to the low protein content in banana peels. This study aimed to increase the protein content of banana peel flour using the solid-state fermentation method by Rhizopus oryzae FNCC 6157 in a tray bioreactor. Optimization of protein production of banana peel flour was done using the central composite design by response surface methodology. The variables used in this study were substrate thickness (1 to 3 cm), aeration rate (2 to 4 L/min), and moisture content (50 to 70%). Statistical analysis was performed using ANOVA and resulted in an excellent quadratic equation model as indicated by the F-value and p-value of 17.77 and 0.0012, respectively, and was statistically significant (p≤0.05). Fermentation conditions at the substrate thickness of 2 cm, aeration rate of 3 L/min, and moisture content of 60% resulted in the highest enhancement of protein content in banana peel flour of 54.08%.