Maximising pitaya (Hylocereus polyrhizus) peel pectin yield through cellulase-assisted extraction: a study on enzyme optimisation

Red-purple pitaya (Hylocereus polyrhizus) peel is a rich source of plant pigment betacyanins and dietary fibre specifically pectin. Pectin's multifunctional properties enable its use in the healthcareindustry. This study investigated the optimum conditions for cellulase enzyme to release maximum pectin from pitaya peel puree. Parameters such as cellulase concentration (50 -300 μL/100 g of puree), pH (3 -5.4), time (30 -180 min) and temperature (25 -50 °C) were varied for cellulase optimisation followed by pectin extraction using water extraction method and pectin yield determination. The optimal conditions for maximising pectin extraction from pitaya peel were a cellulase concentration of 100 μL per 100 g of puree, a pH of 5.40, a temperature of 37 °C, and apre-treatment time of 120 minutes. At these optimum conditions for pre-treatment of puree with cellulase,22.30%of pectin was extracted from pitaya peel pectin using distilled water at pectin extraction conditions reported in our previous study (temperature: 73 °C, time: 67 min, sample to solvent ratio: 1:4). When extraction was performed using varying concentrations of citric acid (0.5 -2.0%) solutions, a maximum pectin yield (24.63%) at 1.5% citric acid concentration was noted. Based on the proximate composition, functional groups and degree of esterification findings, cellulase-assisted extraction demonstrates strong potentialto convert fruit peels into valuable pectin.