Novel insights into the impact of pectin structure on key aroma components of peaches

Pectin has a crucial impact on aroma properties, but their potential interaction mechanisms are still unclear. In this study, 9 key aroma-active components with relative odor activity value (rOAV ≥1) were screened out in 5 peach samples. The variations in molecular weight, monosaccharide composition and conformation of water-soluble pectin (WSP), chelator-soluble pectin (CSP), and Na₂CO₃-soluble pectin (NSP) were then investigated. Significant differences in Fourier transform-infrared spectroscopy profiles (1200-800 cm^-1) were observed, attributed to variations in HG domain (WSP: 14.06 % ~ 53.95 %, CSP: 29.37 % ~ 53.10 %, NSP: 1.27 % ~ 24.21 %) and neutral sugar contents (WSP: 40.84 % ~ 62.96 %, CSP: 5.82 % ~ 21.67 %, NSP: 21.15 % ~ 47.62 %). Furthermore, it was observed that hydrogen bonding and hydrophobic interactions were the main forces between the high methoxyl WSPs and key aroma-active compounds via molecular docking. Compared to aldehydes, terpenoids, lactones, and alcohols were easily affected by the rhamnogalacturonan I (RG-I) domain, especially γ-decalactone and theaspirane with low binding energies of -5.208 kcal/mol and -4.268 kcal/mol. This investigation may contribute to a deeper understanding of the mechanistic role of pectin in regulating peach aroma compounds.