Effects of pectin polydispersity on zein/pectin composite nanoparticles (ZAPs) as high internal-phase Pickering emulsion stabilizers

In the present study, the properties of two apple sourced-pectin (AP-1 and AP-2) were comparative studied, and their influence on the formation of high internal-phase Pickering emulsions (HIPPEs) was investigated. Results showed that AP-2 has lower polydispersity index (PDI = 2.51) than AP-1. Zein/AP-2 complex nanoparticles (ZAPs-2) was able to stabilize 80% oil-phase to form HIPPEs, while ZAPs-1 failed to remain stable at same oil fraction. After correlating GPC (Gel Permeation Chromatography) results of pectins with their emulsion behavior, pectin PDI was found to play an important role in HIPPEs formation. Storage experiments and rheological properties analysis showed that HIPPEs exerted excellent stability and plasticity. Besides, super-resolution microscopy (including cryo-SEM and STED nanoscopy) depicted an intuitive interface structure of HIPPEs. These findings may contribute some basis to manipulating emulsion performance by adjusting pectin properties, as well as to further understanding the behavior of ZAPs at O/W interface.