Comparative analysis of water-soluble pectin structures in orange and pomelo juices: Impact on cloud stability

Water-soluble pectin (WSP) is a key component contributing to cloud stability in not-from-concentrate (NFC) citrus juices. This study investigated the physicochemical and structural properties of WSP isolated from NFC orange (O-WSP) and pomelo (P-WSP) juices, and examined the relationship between WSP structure and cloud stability. Results showed that the O-WSP concentration (0.73 mg/mL) was significantly higher than that of P-WSP (0.43 mg/mL). O-WSP exhibited a markedly higher molecular weight and more branched rhamnogalacturonan I (RG-I) regions compared to P-WSP. AFM and SAXS analyses revealed that O-WSP formed more aggregated structures in solution. Furthermore, O-WSP demonstrated stronger interfacial activity and a lower critical aggregation concentration than P-WSP. The stability of the WSP solutions correlated closely with the cloud stability of the NFC citrus juices. Importantly, O-WSP, with its higher protein, phenolics, and RG-I content, stronger interfacial activity, and aggregation propensity, was associated with reduced cloud stability in NFC orange juices.