Structure relationship of non-covalent interactions between phenolic acids and arabinan-rich pectic polysaccharides from rapeseed meal

Covalent and non-covalent interactions between polyphenols and polysaccharides produced vital consequences on the sensory and nutritive qualities of the many foods. In the present study, the structure dependence of the non-covalent interactions between phenolic acids (PAs) and an arabinan-rich pectic polysaccharide from rapeseed meal (ARPP) was explored. Native RAPP and its hydrolysates as well as twenty-seven structurally diversified PAs were applied. The interaction was determined as the micrograms of PAs adsorbed by per milligram of polysaccharides (Q_e, μg/mg). On one hand, the molecular weight (M_w) of ARPP displayed a significant effect on the Q_e of ferulic acid and a highest value (412.28 μg/mg) was obtained for the ARPP hydrolysate having a M_w of 76 kDa. On the other hand, the substituent profile of PAs greatly affected their Q_e values onto ARPP, although the results are monomer and substituent specific. Specifically, in terms of Q_e, hydroxylation favored the interaction by 35.78% to 271.22%, while methylation and esterification weakened the absorption by 44.78% to 230.71% and 16.48% to 78.68%, respectively. The case of esterification is more complicated that the attachment of OCH₃ at 3-position (-26.14% to -77.04%) is adverse but that at 5-position is highly favorable (156.96% to 190.70%) for the interactions.