罗非鱼蛋白-大豆蛋白共沉淀物的乳化性

Emulsifying properties of tilapia-soybean protein co-precipitates

为研究罗非鱼蛋白-大豆蛋白共沉淀物的乳化性,以罗非鱼肉和脱脂豆粕为原料,按照不同质量比（1∶0、1∶1、2∶1、3∶1、0∶1）混合,采用碱溶酸沉法制备鱼分离蛋白（FPI）、罗非鱼蛋白-大豆蛋白共沉淀物（Co-p）和大豆分离蛋白（SPI）,并探讨了p H、盐浓度、多糖对其乳化活性（EAI）和乳化稳定性（ESI）的影响。结果表明：FPI、Co-p（1∶1）、Co-p（2∶1）、Co-p（3∶1）和SPI的得率分别为62.21%、39.10%、29.58%、18.45%、32.10%（P〈0.05）;p H 3.0时,FPI、Co-p和SPI的乳化活性依次减小,而p H 4.0-10.0时,Co-p（2∶1）和Co-p（3∶1）的乳化活性最好（P〈0.05）;在0%-0.4%Na Cl体系中,Co-p的乳化活性明显强于FPI或SPI;p H 3.0-7.0时,添加0.2%-0.3%的瓜尔豆胶和黄原胶能显著提高蛋白乳化体系的EAI值（P〈0.05）,且Co-p的乳化性较FPI或SPI有明显提高。比较而言,罗非鱼蛋白-大豆蛋白共沉淀物较FPI或SPI有更好的乳化性。

Fish protein isolate （FPI） , tilapia-soybean protein co-precipitates （Co-p） and soybean protein isolate （SPI） were prepared by alkali-solution and acid-isolation. The mixing ratios of tilapia to defatted soybean meal were 1： 0, 1 ： 1, 2： 1, 3：1 and 0： 1, respectively. Effect of pH, salt concentrations and polysaccharides on emulsifying properties of protein co-precipitates were investigated using the emulsifying activity index （EAI） and emulsifying stability index （ESI）. Results showed that the yields of FPI, Co-p （ 1 ： 1 ）, Co-p （2 ： 1 ）, Co-p （3 ： 1 ） and SPI were 62.21%, 39.10%, 29.58%, 18.45% and 32. 10% （P 〈 0.05）. At pH 3.0, the emulsifying ability of FPI was better than that of Co-p or SPI, while at pH 4.0 - 10.0, Co-p （2：1 ） and Co-p （3：1 ） exhibited the highest emulsifying ability （P 〈0. 05）. With NaCl （0 -0.4 mol/L）, Co-p had bigger EAI values than FPI or SPI. In addition, in presence of 0.2% -0.3% guar gum or xanthan gum, at pH 3.0 -7.0, the emulsion systems, especially protein coprecipitates, revealed significant increase in EAI and ESI （P 〈 0.05）. In conclusion, tilapia-soybean protein co-precipitates had better emulsifying properties than FPI or SPI.