Modification of pectin in Japanese persimmon fruit during the sun-drying process

Abstract

Cold-water-soluble pectic polysaccharides (CWPs) from fresh and sun-dried Japanese persimmon ( Diospyros kaki) were fractionated through DEAE-cellulose (phosphate form) column and in both cases, CWPs were separated into five fractions, CWP1, CWP2, CWP3, CWP4 and CWP5. Each CWP3 was subjected to gel filtration chromatography on a Sepharose CL-6B column. Gel filtration showed that solubilization of pectin as high-molecular-weight polymer into CWP3 and depolymerization of CWP3 occurred during the sun-drying process. CWP3 (fresh persimmon) contained galactose as the predominant neutral sugar, whereas arabinose was the predominant neutral sugar in newly solubilized CWP3. A low-molecular-weight fraction of CWP3 (sun-dried persimmon) represented mainly the rhamnogalacturonan backbone of ‘hairy’ regions. The molecular size distribution of CWP3 was affected due to degradation of side-chains. Loss of arabinose occurred at a slower rate than galactose from CWP3. The results imply a softening-associated modification of Japanese persimmon pectin during the sun-drying process.