Characterization of Kiwifruit Xyloglucan

Structural characteristics of xyloglucan are constant in the pericarp cell walls of kiwifruit ( Actinidia deliciosa ) throughout fruit enlargement and maturation. Most of the xyloglucan (XG) persists in the cell walls of ripe kiwifruit. XG from the pericarp tissues of 36-h ethylene-treated kiwifruit was extracted as hemicellulose II (HC-II) with 4.28 M KOH containing 0.02% NaBH₄, and purified using iodine precipitation and subsequent anion-exchange chromatography. This purifying protocol increased XG purity from 50 mol% in HC-II fraction to 62 mol% in the purified XG powder. The molar ratio of glucose: xylose: galactose: fucose in the purified XG was 10: 6.9: 2.1: 0.3. Gel permeation chromatography indicated that purified XG had an average molecular-mass of 161 KDa, a value that exceeds the 95 KDa M_r determined for total polymeric sugars. Sugar linkage analysis confirmed the lack of fucose in the kiwifruit XG, but a small amount of arabinoxylan and low M_r glucomannan remained associated with this fraction.