摘要
The present work found that at neutral pH, double emulsions could be simply fabricated with SPI preheated at acidic pH by one-step method. The effects of heating time on the solubility of SPI at pH 7.0 and the properties (e.g. cream rate, particle size) of double emulsions were further studied. The results showed that the acidic heating treatment decreased the solubility of SPI at pH 7.0 (native SPI, 78.60%; preheated SPI, 36.02%~53.39%), and the behavior was dependent on the heating time. This phenomenon may be related to the formation of insoluble protein fibrillar aggregates, which are mainly sustained by hydrogen bond and disulfide bond. The acidic heating treatment obviously improved the creaming stability of emulsions, and the longer heating time resulted in better effects (native SPI, 38.70%; SPI preheated with 2~6 h, 34.90%~36.50%; SPI preheated with 12~20 h, 17.50%~19.70%). However, the droplet size of emulsions became larger (native SPI, 24.63 μm; preheated SPI, 28.12~33.97 μm). In addition, an increase in the oil content also decreased the cream rate and droplet size. With the oil content increased from 20% to 60%, the cream rate decreased from 76.20% to 3.30%, and the droplet size decreased from 28.23 μm to 19.06 μm. The present work provides a new way to fabricate double emulsions with controllable properties.
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