From waste to wonder: the ultrasonic-enzyme-fermentation process transforms virgin coconut oil press cake into a food ingredient

Virgin coconut oil press cake (VCOPC), a protein and fiber rich byproduct of coconut oil extraction, remains underutilized despite its nutritional potential. In this study, we developed a continuous bioprocessing strategy that integrates ultrasonication, enzyme-assisted hydrolysis, and lactic acid bacteria fermentation to transform VCOPC into a food ingredient with enhanced nutritional and functional properties. The ultrasonication process achieved a 63% solubilization of the press cake under optimized conditions (1.62 bar, 95 min), it effectively broke down the rigid polysaccharide-protein-lipid matrix and reducing particle size from 2.5 µm to 0.35 µm. Enzymatic treatment markedly increased soluble protein content (up to 137 mg/g) and free amino groups (up to 11.8 mmol/g), while fermentation with L. acidophilus and L. rhamnosus resulted in a 3-log increase in bacterial growth. Functional assessment of the various ingredients obtained by this bioprocessing approach showed high solubility and foaming capacity due to superior interfacial activity. This study demonstrates the successful conversion of coconut by-products into a nutritionally enriched food ingredient with enhanced techno-functional properties. Ultrasonication contributed to the highest yield, while enzymatic and microbial processes delivered the desired biochemical transformations. Combining initial mechanical disruption with enzyme hydrolysis and fermentation represents an effective and sustainable pathway for by-products upcycling and fosters circular innovation within the tropical food economy.