THE WALL-BOUND PHENOLICS OF CHINESE WATER CHESTNUT (ELEOCHARIS-DULCIS)

Chinese water chestnut (CWC) is a vegetable in which the edible storag e parenchyma exhibits thermal stability to texture. This property has been attributed to the presence of large quantities of simple phenolic s which exhibit pH-dependent autofluorescence. The identities of the m ajor phenolic components were assessed by reverse-phase HPLC after seq uentially extracting them with increasing strengths of alkali from pur ified CWC cell wall material. The levels of cold-alkali-liberated phen olics were very high (12.2 mg g(-1) cell wall material). Ferulic acid dominated the monomeric phenol fraction (7.2 mg g(-1)), although small quantities of aldehydes were also released. A number of different dif erulic acids were also identified, of which the 8-O-4'-linked form was the major component (2.8 mg g(-1)), with 8,5'-diferulic acid and the familiar 5,5'-form also present in smaller quantities (910 and 988 mu g g(-1), respectively). Hence, approximately 40% of the ferulic acid i n the wall was present as dimers which are potentially available to fo rm extensive, heat-resistant cross-links between polysaccharides withi n the wall, and between cells.