From byproducts to bioresources: cocoa shell solid-state fermentation lipase as a low-cost esterification catalyst

Solid-state fermentation (SSF) of lignocellulosic biomass enables the reduction of costs associated with obtaining enzymes. Utilizing cocoa shells with high lipid content makes it possible to modulate microbial metabolism, thereby enhancing the release of lipases. The resultant cell-free crude enzyme preparation can be directly employed for esterification purposes and other industrial applications. In this study, we present the utilization of Penicillium roqueforti ATCC 10110 in solid-state fermentation (SSF) to harness cocoa shell byproducts to produce lipase, subsequently employed as an esterification catalyst. The crude enzymatic extract derived from SSF demonstrated robust lipolytic activity across various substrates: olive oil (18.0 U/g), soybean oil (15.0 U/g), palm oil (16.5 U/g), residual soybean oil (6.5 U/g), and residual palm oil (8.0 U/g). Furthermore, the lipase exhibited significant activity towards the synthetic substrate p-nitrophenyl phosphate (48.64 U/g). For optimizing lipase-catalyzed esterification of oleic acid and residual soybean oil, a Doehlert design was employed. Notably, remarkable conversion rates of 56.07% and 91.57% were achieved for these products, respectively. A meticulous examination and interpretation of all data collectively propose this approach as a feasible avenue for application within the biodiesel sector, with potential cost-saving implications.