Optimisation of pectin production from dragon fruit peels waste: drying, extraction and characterisation studies

摘要

Reutilisation of agricultural wastes is a major challenge faced by the research community. The current study aimedto address this issue by recovering commercial pectin from dragon fruit peels by investigating the pretreatment andextraction process and their parameters. Optimum oven-drying temperature was identified at 45 ℃ with the highestpectin yield (6.27%) and the lowest ash content (8.34%). Investigation of the drying kinetics revealed Page’s model as thebest-suited model to the experimental data in terms of the highest R~2 (0.99685) and lowest RSME (0.0002). A three-factor,three-level Box–Behnken design was applied to optimise ultrasound-assisted pectin extraction for the parameters oftime, temperature and solid-to-liquid ratio. Under the optimised condition of 32 min at 85 ℃ with a ratio of 1:30 g/ml,a maximum pectin yield (23.09%) was obtained as compared to the predicted value (22.84%). The extraction kineticsstudy showed the logarithmic model was the best-fitted model to represent pectin’s extraction in terms of the highestR~2 (0.9384) and lowest RMSE (0.821). Degree of esterification of pectin pre- (36.36%) and post-optimisation (33.27%)characterised it as low methoxyl pectin. The ash content of pectin was reduced by 23.65% revealing that higher-puritypectin was extracted following optimisation. Comparison of the Fourier transform infrared spectra with commercialgradepectin shows the extracted pectin from dragon fruit peels has high potential in food applications. The currentstudy recommends waste dragon fruit peels as a sustainable alternative source for high-value pectin.