Fermentation techniques for protein enrichment of cassava peel

The use of agro-industrial by-products such as unconventional feeds in animal production is an alternative for reducing the high costs associated with conventional feeds. The present study aimed to evaluate the effect of aeration, pH adjustment, the use of yeast (Saccharomyces cerevisiae) and the amount of urea on the enrichment of cassava peel (CPe) by mixed fermentation and their impacts on chemical composition, protein fractionation, nutrient cost and yield. Two experiments were conducted. Experiment 1 evaluated the effects of aeration (A) and pH adjustment (pHad). Experiment 2 assessed the effects of yeast inoculation (Y) and urea dose (U). Yeast treatments consisted of either inoculation at 50 g kg^-1 CPe or no inoculation, while urea was applied at 60 g kg^-1 CPe (U60) or 120 g kg^-1 CPe (U120).

In Experiment 1, an interaction (P < 0.05) was observed on the concentration of ash, ether extract, protein fraction A, fresh matter yield and dry matter cost. Aeration of the solutions applied to CPe increased crude protein (CP) concentration. In Experiment 2, no interaction was observed for CP. Separately, the U120 dose increased CP content because of higher nitrogen availability, whereas yeast inoculation also significantly increased CP, suggesting the conversion of non-protein nitrogen into microbial true protein (yeast biomass).

Mixed fermentation is effective in increasing the protein concentration of CPe. Aeration has a greater impact on the protein content than pH adjustment. Furthermore, the urea dose has a greater impact on protein content than the yeast inoculation in the enrichment process of non-aerated CPe. © 2026 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.