The objective of this work was to extract high methoxyl (HM) pectin with oxalic acid, characterise its physicochemical properties and evaluate its dispersion stability in acidified milk drink (AMD). HPSEC-MALLS analysis revealed that the obtained HM pectin was high in molecular weight (522.4 kDa). The ζpotential of the obtained HM pectin in aqueous solution at pH 4.0 was −31.5 mV. The AFM images proved that the obtained HM pectin contained several long linear molecules. The apparent diameter of AMD stabilised by the obtained HM pectin was 636 nm at the concentration of 3.0½. The stability analysis of AMD and the microscopic observation with confocal laser scanning microscopy (CLSM) proved that the obtained HM pectin was a prominent stabiliser in AMD.

SummaryThe acid heating extraction process is commonly employed to extract pectin from citrus peels, which results in the leaching of bioactive constituents into solvents. However, the discharge of these solvents represents a significant loss of valuable resources. To address this issue, this study aims to identify the composition and concentration of the bioactive constituents that escape into the solvents and propose an extraction process based on an ethanol‐salt aqueous two‐phase system (ATPS). The well‐designed ATPS enables the enrichment and recovery of the bioactive constituents, and the findings demonstrate that the ethanol/sodium citrate‐based ATPS can recover up to 80.61% of limonoids, 84.11% of flavonoids, and 88.09% of polyphenols that escape at an enrichment efficiency of 50.00%. Moreover, HPLC‐DAD and UPLC‐HRMS analysis of the ATPS extracts revealed the presence of nine bioactive constituents, including flavonoids, phenolic acids, and limonoids. Remarkably, in vitro antioxidant capacity studies indicate that the ATPS extracts exhibit superior antioxidant activity compared to the vacuum‐concentrated solution. Thus, these results suggest that the application of ATPS extraction is a feasible and promising strategy for the recovery of bioactive constituents.