Effects of high voltage dielectric barrier discharge on the extraction and properties of pectins from watermelon rinds

Abstract

High-voltage dielectric barrier discharge (DBD) pretreatments of watermelon rinds were conducted at 12, 16, and 20 kV cm-1 to extract pectin. The DBD pretreatment at 20 kV cm−1 had significantly impacted pectin extraction, increasing yield from 17.4% to 18.5%. A kinetic study had shown that pectin extraction can be properly modeled using a pseudo-first-order kinetic model. The pectins obtained from conventional extraction and DBD pretreatment had galacturonic acid contents ranging from 79.02% to 80.25% and average molecular weights between 222 and 402 kDa. The exposure to the DBD pretreatment had increased total monosaccharides, branching index, and the rhamnogalacturonan domain of pectin. Fourier transform infrared spectroscopy analysis had not indicated a formation of new functional groups or significant structural changes but had increased functional group intensity. X-ray diffraction showed no significant changes in pectin's crystalline structure due to DBD pretreatment.