A novel preparation strategy of emulsion gel solely stabilized by alkaline assisted steam-cooking treated insoluble soybean fiber

Abstract

In this work, the insoluble soybean fiber, which was derived from okara facilely prepared by alkaline assisted steam-cooking treatments (AST-ISF), was used to prepare emulsion gels through regulating oil volume fraction (φ, 0.1–0.6) and ISF concentration (c, 0.05%–0.5%). AST-ISF was mainly composed of insoluble fiber (82.99 ± 0.24%), and most proteins were removed by alkaline treatment. AST endowed ISF with a higher crystallinity index (47.30 ± 0.82%) and moderate interfacial wettability (87.2 ± 1.2°), which facilitated the adsorption of AST-ISF at the oil-water interface and the formation of a stronger gel-like network structure. Raw okara and alkaline treated ISF could not form emulsion gels. In contrast, the emulsion gels could be formed by AST-ISF, and it was enhanced by AST-ISF adsorbing and entrapping with the oil phase. Oil volume fraction was a crucial factor affecting the microstructure. Especially when φ = 0.5, the degree of droplet aggregation was particularly prominent, and the elastic modulus increased up to about ten times compared with that at φ = 0.1. The minimum AST-ISF concentration to form emulsion gel was 0.3%. The study revealed that the structure of AST-ISF stabilized emulsion gel was characterized as a hybrid network structure composed of tightly packed oil droplets with cross-linked ISF in the continuous phase.