Optimization of Ultrasound-Assisted Pectin Extraction from Durian Rind

Durian (Durio zibethinus) rind is fruit waste and can be used as a source of pectin. This study aimed to optimize the pectin extraction process using the ultrasound-assisted extraction (UAE) method and evaluate its physicochemical properties. Initially, influencing factors in UAE, such as solvent type (HCl, citric acid, acetic acid, and n-hexane), extraction time (10, 15, 20, 25, and 30 minutes), extraction temperature (40, 50, 60, 70, and 80 degrees C ), sample:solvent ratio (1: 14,1: 17,1: 20,1: 23, and 1: 26 g/mL), duty of cycle (20, 40, 60, 80, and 100%), and amplitude (20, 40, 60, 80, and 100%) were evaluated. Using central composite design (CCD), a temperature of 74 degrees C and sample:solvent ratio of 1 : 20 g/mL were determined as optimum conditions with an estimated pectin yield of 6.07%. This value is in accordance with the experimental result of 6.12%. Extraction with UAE resulted in a higher pectin yield compared to the conventional extraction method using a water bath shaker. The pectin had a degree of esterification (DE) of 44.35%, a moisture content of 4.34%, and an ash content of 1.08%. The FTIR spectra proved the presence of functional groups in pectin, the XRD patterns suggested the structure was more amorphous than crystalline, and SEM showed a smooth pectin surface.