COMPARISON OF CHANGES IN BERRY FIRMNESS AND CELL WALL COMPONENTS DURING RIPENING AMONG GRAPE CULTIVARS

Abstract

      In this work, we investigated the developmental changes in cell-wall polysaccharides associated with the physiological properties of pericarp and mesocarp tissues of grape berries during ripening, and aimed to clarify the mechanisms involved in the softening process. The firmness of fruits, ethanol insoluble solids content, changes in pectins content, and hemicellulose and cellulose content were studied. The results showed that the changes in pectic fractions occurred dramatically in the sub-epidermal layer (pericarp), and the amount of water soluble pectin (WSP) increased greatly during berry ripening in the three cultivars tested, while the changes were not significant in mesocarp and/or other pectic polysaccharide fractions. Moreover, the hemicellulose content did not change markedly from stage 1 to stage 3, and decreased significantly to stage 4 in all cultivars, while the cellulose content decreased markedly during ripening in all cultivars analyzed, both in pericarp and mesocarp tissues.