Optimization of Pectin Extraction from Dragon Fruit Peel Using Cellulase Enzyme and Microwave-Assisted Method

Vietnam’s tropical monsoon climate provides ideal conditions for cultivating and exporting fruits, particularly dragon fruit (Hylocereus spp.). This study aims to utilize agricultural waste from dragon fruit to develop affordable fiber supplement tablets that support Vietnamese health. Pectin was extracted using varying concentrations of cellulase enzyme (0 %, 0.4 %, and 0.8 % (wt %)) combined with microwave treatment durations of 0 s, 30 s, and 60 s, and extraction times of 60 min, 80 min, and 100 min. A fractional factorial design was employed to evaluate the effects of these three factors on pectin yield, and response surface methodology (RSM) was applied to optimize the extraction process. Findings indicated that extraction time had no significant effect on pectin yield, while microwave duration and enzyme concentration were influential factors. The RSM model demonstrated strong predictive accuracy with an R² value of 0.9334. The optimal conditions were identified as a microwave treatment time of 48.05 s and an enzyme concentration of 0.6396 % (wt %), yielding a predicted pectin recovery of 27.026 %, closely matching the actual yield of 27.24 %. Furthermore, the extracted pectin exhibited inhibitory activity against alpha-amylase with an IC20 =1,465.26 µg/mL and shows free radical scavenging activity against ABTS radicals with an IC50 = 171.6 µg/mL. The FT-IR spectra indicated that the extracted pectin shares a similar chemical structure with commercial pectin.