Abstract:
Abstract: Zeta potential of protein particles was an essential indicator to evaluate soymilk stability, and before the measurement, dilution of soymilk was regarded as a necessary procedure. In order to guarantee the accuracy and scientificity of analysis results of zeta potential, appropriate diluent should be chosen. In this study, deionized water and soymilk permeate were respectively used to dilute soymilk, and the effects of these two diluents on zeta potential, size distribution, pH value and electrical conductivity of soymilk were compared. According to the results, if soymilk was diluted by deionized water, a remarkable increase in the absolute value of zeta potential could be observed with the increase of dilution ratio (*P<0.05), and it was mainly attributed to the dissociation of soymilk aggregations and the decrease of ionic strength, since the size of protein particles became smaller, the pH value deviated from that of soymilk, and the electrical conductivity was significantly decreased after the dilution (*P<0.05). By contrast, when soymilk permeate was the diluent of soymilk, the absolute value of zeta potential, as well as the size distribution of protein particles, the pH value and the electrical conductivity, did not change with the increase of dilution ratio, which indicated that the charged stability of soymilk protein particles was well kept after the dilution. Therefore, soymilk permeate could be considered as an ideal diluent in the measurement of zeta potential.