Abstract: Oil-in-water emulsions were prepared by combinations of various concentrations (0.5%, 1%, 2% and 3%) of soybean protein isolate (SPI) with 3% soybean oil. We analyzed the differences of these emulsions in stability under various centrifugal forces and viscosity under various shearing rates. Meanwhile, we evaluated the storage stability of these emulsions by measuring the turbidity, and the changes in particle size and Zeta potential and performing visible and microscopic observations. The above experiments consistently showed that the emulsion with 3% SPI had the best stability. Moreover increasing SPI concentration resulted in higher viscosity and better stability. Despite of having changes during storage, average particle size and Zeta potential were not suitable to be used for evaluating the stability of emulsions. This study further confirms that the centrifugation method allows rapid and accurate prediction of the stability of emulsions and therefore can be used in product development and testing.

Key words: soybean protein isolate, emulsion, stability analysis, centrifugation method