Improving the emulsion freeze-thaw stability of soy protein hydrolysate-dextran conjugates

The processing parameters of Maillard reaction products (SPH-D) from soy protein hydrolysates (SPH) and dextran (D) were assessed according to the degree of glycation, browning index and creaming index to improve the freeze-thaw stability in an oil-in-water emulsion. SPH-D conjugates were produced through the wet method under optimal conditions for each factor at a mass ratio of 2:3, SPH concentration of 40 g/L, temperature of 85 degrees C and dispersion in a phosphate buffer (pH 8) incubated for 1 h. Such conditions reported the lowest creaming index and the best freeze-thaw stability. The emulsion prepared from SPH-D was reduced by 48%, 40% and 48% after each freeze-thaw cycle. Meanwhile, a freeze-thaw stability reduction was also observed with an excessive Maillard reaction. Additionally, the confocal laser scanning microscopy analysis indicated that the optimum SPH-D emulsion was more stable to the freeze-thaw treatment and could be used as an effective emulsifier in frozen foods.