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Soy/whey protein isolates: interfacial properties and effects on the stability of oil‐in‐water emulsions
Author(s) -
Zhang Xiaoying,
Zhang Shuang,
Xie Fengying,
Han Lu,
Li Liang,
Jiang Lianzhou,
Qi Baokun,
Li Yang
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.10638
Subject(s) - whey protein isolate , emulsion , creaming , adsorption , whey protein , chemical engineering , soy protein , chemistry , surface tension , oil droplet , chromatography , viscosity , materials science , composite material , organic chemistry , food science , thermodynamics , physics , engineering
Abstract BACKGROUND The adsorption of proteins at oil/water interfaces can reduce interfacial tension and increase emulsion stability. However, emulsions stabilized by soy protein isolate (SPI) are not sufficiently stable. Using SPI as a control, a theoretical basis for the adsorption behavior of mixed SPI and whey protein isolate (WPI) at the oil/water interface was established and the effects of the protein ratio and content on the emulsion stability were studied. RESULTS Compared to SPI solution, SPI–WPI mixed solutions were found to reduce the size distribution of emulsion droplets and significantly improve the emulsion stability. Among the studied protein contents and ratios, the protein content of 0.2 g kg −1 and SPI/WPI mass ratio of 1:9 offered the lowest creaming stability index (15%), the smallest droplet size (278 nm), and the largest absolute value ζ‐potential (35 mV), i.e. the emulsion stability was excellent. The largest dilatational modulus (10.08 mN m −1 ), dilatational elasticity (10.01 mN m −1 ), and dilatational viscosity (1.18 mN m −1 ), were observed with a protein content of 0.15 g kg −1 (SPI/WPI ratio of 1:9), along with a high interfacial protein adsorption capacity (47.33%). SPI–WPI complexes form a thick adsorption layer around oil droplets, resulting in an increase of the expansion modulus of the interfacial layer. CONCLUSION SPI–WPI complexes can form a thick adsorption layer around oil droplets, resulting in increased expansion modulus of the interfacial layer, which improves emulsion stability. © 2020 Society of Chemical Industry