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Characterization and analysis of an oil‐in‐water emulsion stabilized by rapeseed protein isolate under pH and ionic stress
Author(s) -
Wu Jin,
Xu Feiran,
Wu Ying,
Xiong Wenfei,
Pan Mengmeng,
Zhang Na,
Zhou Qi,
Wang Shijie,
Ju Xingrong,
Wang Lifeng
Publication year - 2020
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.10532
Subject(s) - creaming , emulsion , ionic strength , flocculation , chemistry , rheology , zeta potential , chemical engineering , chromatography , rapeseed , solubility , circular dichroism , materials science , aqueous solution , organic chemistry , food science , composite material , biochemistry , nanoparticle , engineering
BACKGROUND Presently, identifying natural compounds as emulsifiers is a popular topic in the food industry. Rapeseed protein isolate (RPI) is a natural plant protein with excellent emulsifying properties, but it has not been systematically developed and utilized. RESULTS This study investigated the surface hydrophobicity, wettability, and protein solubility of RPI to further explain its emulsifying behavior in emulsion systems. Nanoemulsions stabilized by RPI at varying protein concentration, pH, and ionic strength were prepared. The size distribution, zeta potential, flocculation index, creaming index, microstructure, rheology, and protein secondary structure of emulsions were measured. The emulsion stabilized by 20 g L −1 RPI at pH 10.0, 200 mmol L −1 ionic strength revealed an appropriate droplet size of 555 nm and the most internal gel strength without creaming phenomenon. Circular dichroism spectroscopy showed a positive correlation between emulsion stability and α ‐helix ratio, indicating the environment factors affected emulsion stability by acting on its hydrogen bonds. CONCLUSIONS This study demonstrates that RPI is a practical emulsifier for stabilizing nanoemulsions. About 20 g L −1 RPI can stabilize 100 mL L −1 oil in water; stable emulsions can be formed at most pH conditions (except 7.0); ion addition will aggravate the emulsion flocculation, but also increase the internal gel strength. © 2020 Society of Chemical Industry