The aim of the present study is to characterize the mechanical properties of O/W emulsion gels stabilized through soy protein isolate (SPI)-xanthan gum (XG) complex and to elucidate their practical usefulness in plant-based processed meat products. O/W emulsions prepared by mixing aqueous solutions of SPI-XG complexes, which was formed via electrostatic interactions under acidic conditions (pH 4.0), with plant oil were gelled in the presence of several hydrocolloids. Effects of hydrocolloid composition, oil type and load, and oil droplet size on the mechanical properties of the emulsion gels were investigated by dynamic viscoelasticity measurements, and fluorescence microscopy was performed for observation of the oil droplet dispersion. Results indicated that methylcellulose should be required to provide the gels with heat resistance and that the type of oil used should affect dynamic storage modulus (G') of the gels particularly at lower temperatures. It was also found that increased oil load should decrease the gel's resistance to deformation, making the gel structure brittle, and that oil drop size should affect G' and dynamic loss modulus (G") at lower strains. Food application tests indicated that the emulsion gels used had a great impact on the mechanical properties of plant-based meat patties. These findings would contribute to the utilization of the emulsion gels as a lipid portion in plant-based processed meat products, leading to the progress of industrial practice.
Keywords: complex; dynamic viscoelasticity; emulsion gel; plant-based; soy protein; xanthan gum.
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