The search for sustainable and cost-effective substrates for bioethanol production has intensified interest in agro-industrial by-products. This study aimed to evaluate the impact of pre-treated palm kernel cake (PKC), a by-product of palm oil processing, on industrial alcohol production and associated biochemical changes. To enhance its fermentation suitability, PKC was subjected to solid-state fermentation, autoclaving, and acid hydrolysis over 72 hours before undergoing submerged fermentation with commercial baker's yeast (Saccharomyces cerevisiae). Biochemical parameters including soluble protein, glucose, phenol, total flavonoid concentration (TFC), and enzymatic activities (phytase and mannanase) were measured alongside fermentation indicators such as pH, total soluble solids, specific gravity, and alcohol concentration. The results revealed that pre-treated PKC showed significantly higher (p < 0.05) levels of soluble protein, phenols, and TFC compared to untreated PKC, while glucose concentration decreased markedly, suggesting efficient substrate utilization. Enhanced enzymatic activity and free radical scavenging capacity were also observed in the pre-treated groups. Notably, solid-state fermentation yielded the highest specific gravity and alcohol output. The pH increased significantly during fermentation, while total soluble solids declined post-fermentation, further supporting substrate breakdown. These findings indicate that pre-treatment, particularly solid-state fermentation, improves the biochemical profile of PKC and enhances its potential for industrial alcohol production, demonstrating its viability as a low-cost, nutrient-rich substrate for bioethanol generation.
Ughe et al. (Thu,) studied this question.