Changes in the pectic fraction of bush butter (Dacryodes edulis (G Don) HJLam) fruit pulp during ripening

CDTA-soluble polysaccharides were extracted from cell wall material (prepar ed as alcohol-insoluble solids) of bush butter fruit endocarp tissue at thr ee stages of ripeness. The amount of soluble pectins remained constant but they underwent a gradual depolymerisation during ripening. The CDTA extract s were fractionated by anion exchange and the subfractions were analysed fo r their sugar composition and molecular weight distribution. For all degree s of ripeness the extracts were composed of three minor peaks and two major peaks. The minor peaks appeared to be composed of xyloglucan and mannan-ty pe polymers for the first peak and arabinogalactan-type polymers for the ot her two peaks. The two main peaks were retained on the column. The first wa s exclusively composed of homogalacturonan polymers and the second containe d principally highly branched rhamnogalacturonan polymers. During ripening, both homogalacturonan and rhamnogalacturonan populations were modified. Mo difications in the rhamnogalacturonan fraction mere principally marked by t he accumulation of low-molecular-weight rhamnogalacturonan polymers in the course of ripening. (C) 2001 Society of Chemical Industry.