Abstract:

In order to reveal the effect of high-intensity pulsed electric field （PEF） treatment on the stability of the dispersion system of soy protein isolate （SPI） solutions, the ξ potential, the types of amino acids and the surface tension were investigated, with 10mg/L and 20 mg/L SPI solutions as the samples. The results indicate that （1） with the increase of PEF intensity, the absolute values of ξ potential of the two SPI solutions first increase and then decrease; （2） the ξ potential of 10 mg/L SPI solution reaches -27.60 mV with a maximum absolute value at a PEF intensity of 10 kV/cm, while that of 20 mg/L solution reaches - 32. 57 mV with a maximum absolute value at 20 kV/cm ; （3） the variation of ξ potential accords with that of the content difference Dn/p between the negatively- charged amino acids and the positively-charged amino acids; and （4） with the increase of PEF intensity, the surface tension of SPI solutions first increases and then decreases at 25 - 35 kV/cm after a constant stage. It is thus concluded that PEF treatment affects the polarity and electronegativity of amino acids and further affects the interaction among protein molecules, thus resulting in the variation of ξ potential and solution stability.

Key words: high-intensity pulsed electric field, soy protein isolate, &xi, potential, surface tension, amino acid analysis