Development of a Continuous Flow Microreactor for the Enzymatic Synthesis of Structured Lipids Using Nigerian Palm and Coconut Oils

Structured lipids with tailored fatty acid composition offer health benefits including improved lipid metabolism and enhanced nutrient absorption, and Nigerian palm and coconut oils provide rich feedstocks for their enzymatic synthesis. Conventional batch enzymatic synthesis of structured lipids is limited by mass transfer constraints and enzyme stability issues. This study develops and optimises a continuous flow microreactor system for the immobilised lipase-catalysed synthesis of structured lipids from palm olein and coconut oil produced in Cross River and Rivers States, South South Nigeria. The theoretical contribution is a microreactor design model integrating enzyme kinetics (Michaelis-Menten with competitive substrate inhibition), heat and mass transfer in microchannels, and residence time distribution analysis. Lipase from Thermomyces lanuginosus was immobilised on functionalised silica microbeads packed into the microreactor. The effects of residence time, temperature, substrate molar ratio, and water activity on structured lipid yield and enzyme stability were investigated using a full factorial design. The continuous flow microreactor achieved 87 percent conversion to the target structured lipid 1,3-dipalmitoyl-2-olein in 15 minutes residence time, compared to 78 percent after 8 hours in batch processing, with a 3-fold improvement in volumetric productivity. Enzyme half-life under continuous flow operation was 285 hours. The study contributes an original microreactor design model, a detailed kinetic parameter set for the Nigerian feedstock substrates, and a validated process for structured lipid synthesis. Keywords: microreactor, structured lipids, enzymatic synthesis, palm oil, continuous flow