Effect of degree of esterification on the stability of high internal phase Pickering emulsions (HIPPEs) fabricated with pectin‐whey protein isolate complexes

Summary This study examined the effects of different degree of esterification (DE) on the stability of high internal phase Pickering emulsions (HIPPEs) fabricated using pectin‐whey protein isolate complexes. The modified pectin with different DE was prepared using the alkali de‐esterification method with high methoxyl pectin (HMP). The impact of DE on the conformational changes of pectin and whey protein isolate (WPI) during the complexes formation was examined using Fourier transform infrared spectroscopy (FTIR) and fluorescence spectroscopy. Citrus pectin (CP)–WPI complexes and camellia oil were used to create an emulsion with a self‐supporting structure of 75% internal phase volume. The thermal, centrifugal, storage and freeze–thaw stabilities of CP–WPI stabilised HIPPEs with different DE were evaluated and the results revealed that the low methoxyl pectin (LMP) produced via alkali de‐esterification altered the charge density of pectin. Compared with the untreated pectin, the electrostatic interaction between CP–WPI complexes was enhanced and the stability of CP–WPI stabilised HIPPEs was improved. The study will help to better understand the interaction between CP and WPI, enhance the efficiency of the pectin–protein delivery system and improve the utilisation rate of citrus pectin, which has important guiding significance.