Response Surface Methodology for Simple Non-Acid Ultrasonic-Assisted Extraction of Pectin from Taiwan’s Citrus depressa H. Peels

Abstract

Exploration of pectin from Citrus depressa H. peels (CD pectin) could add value to the waste arising from Citrus depressa H. beverage products. Preliminary analysis showed that temperature and acidity were insignificantly affect pectin yield, degree of esterification and DPPH scavenging activity. In order to optimize the ultrasonication time and solid: solvent ratio (SLR) of CD pectin extraction, response surface methodology central composite design (RSM-CCD) was used as the statistical tool. The optimum UAE conditions were: extraction time 39.96 minutes and solid: iquid ratio 1:20 (w/v). Under these conditions, the pectin yield was 16.07%, with 83.49% DPPH scavenging activity and 62.46% degree of esterification. The prediction model with a 0.922 desirability value was verified with adequate “lack of fit” values and confirmed consistent response in high and low prediction intervals (95%). Titration analysis, FTIR-ATR, NMR and XRD spectroscopy had been done to the dried pectin, and found that CD pectin is considered as high methoxylated (DE > 50%) with amorphous and crystalline structures. CD pectin peel also exhibited high DPPH scavenging activity (74.14 – 83.56%) that the food industry could potentially use as natural antioxidants. Keywords: Ultrasonication, Pectin, Optimization, Structural, Functional