Structure of the polyphenolic component of suberin isolated from potato (Solanum tuberosum var. Nikola)

Abstract

Suberin is present in the underground parts of vegetables and in the bark of trees. Characterization of suberin and the structure of its polyphenolic component have been hampered by insolubility of the polymers. Thus, enzymatically isolated and extractive free suberin enriched fraction from potato, Solanum tuberosum var. Nikola, and the chemically further fractionated phenolics were characterized in solid state by FTIR, DSC, and elemental analysis to identify the groups and to verify success of isolation. For MW and quantitative determination of the groups, polymers were solubilized in ionic liquid derivatized and analyzed by GPC and (31)P NMR. Suberin enriched fraction, MW = ca. 44 x 10(3) g/mol, is a mixture of carbohydrates and polyesters of aliphatic long chain hydroxy fatty acids and diacids linked via ester bonds to the phenolics, MW = ca. 27 x 10(3) g/mol, formed by guaiacyl- and p-hydroxyphenyl structures. Phenolics in peels may be important sources of antioxidants for various applications.