Texture and microstructure of emulsions prepared with soy protein concentrate by high-pressure homogenization

Oil-in-water emulsions containing a commercial fraction of soy protein concentrate (SPC) and 20 g of soybean oil/100 g emulsion were characterized by looking at stability, particle size, surface adsorption, microstructure and rheological properties. The effect of heating at 82°C for 2 min before homogenization at 80 MPa on the rheological properties and microstructure of the emulsions was also studied. All emulsions showed a gel-like behavior, stability to creaming and did not separate during quiescent storage for 20 days at 4°C. All emulsions with a concentration of 2 g of SPC/100 g were characterized by a creamy texture. No significant differences in microstructure and stability to creaming were shown between heated and unheated emulsions. However, heat treatment resulted in emulsions with higher elastic moduli (G′) than those of unheated emulsions. In addition, heat treatment caused preferential adsorption of the basic subunits of 11S protein onto the oil-in-water interface. The unique properties described in this work have never been reported for oil-in-water emulsions containing soy proteins. These findings may lead to the utilization of high-pressure homogenization of SPC in the development of novel soy-based foods.