pH Driving the Self-Assembly of Hydrolyzed Edible Dock Protein and Myricetin

The amphiphilic peptides formed by moderate enzymatic hydrolysis of proteins can self-assemble into various structures at different pH levels, resulting in differences in the encapsulation efficiency of hydrophobic substances. In this work, a new plant protein of edible dock protein (EDP) was moderately hydrolyzed by Bacillus licheniformis proteinase to prepare hydrolyzed edible dock protein (HEDP). The self-assembly behavior and interaction mechanism of HEDP with myricetin (Myr) at different pHs were explored. The results showed that the loading capacity of Myr by HEDP was 13.86% higher than that of EDP before enzymatic hydrolysis. Moreover, under pH 9.0, the zeta potential, particle size, and PDI of the Myr-HEDP were -34.77 mV, 119 nm, and 0.33, respectively. Meanwhile, the Myr at this pH had the highest encapsulation efficiency (94.55%) and loading capacity (24.8%). Transmission electron microscopy exhibited that the Myr-HEDP nanomicelles had an obvious core-shell structure. Spectroscopy experiments confirmed that there were varying intensities of hydrogen bonding and hydrophobic interactions between HEDP and Myr at different pHs, wherein the binding intensity was largest at pH 9.0. Additionally, the stability evaluation indicated that the UV, thermal, storage, and digestive stability of Myr within the Myr-HEDP nanomicelles at pH 9.0 were more stable than at other pH conditions. In summary, pH 9.0 was more conducive to the self-assembly of HEDP and Myr, forming stable composite nanomicelles. This study will provide an important input into designing more stable and efficacious EDP delivery systems.