Structural characterization of water-soluble pectin in NFC orange juice during cloud destabilization

Water-soluble pectin (WSP) serves as a critical component of colloidal cloud systems in not-from-concentrate (NFC) orange juice, affecting its turbidity, stability, and consumer acceptability. This study examined the physicochemical and structural properties of WSP collected from centrifuged cloud precipitate after 0 or 15 days (0d-P and 15d-P) and serum fraction after 15 days (15d-S) of chilled storage. WSP composition was influenced by storage time and phase. 0d-P had the highest neutral sugar content (RG-I region) but the lowest uronic acid content (HG region), followed by 15d-P, while 15d-S exhibited the opposite trend, which suggested RG-I-rich WSP aggregated easily, forming insoluble materials, whereas HG-rich WSP remained soluble. SAXS analysis indicated that 0d-P contained more three-dimensional structures, indicating greater aggregation tendencies, followed by 15d-P. Overall, WSP in orange juice was found to aggregate over time, with RG-I-rich WSP forming insoluble state, whereas HG-rich WSP maintained its solubility and contributed to cloud stability.