黄原胶对罗非鱼蛋白-大豆蛋白混合体系乳浊液稳定性的影响

Effect of xanthan gum on emulsion stability on tilapia and soybean protein mixture

以罗非鱼和豆粕为原料,采用碱溶-等电点沉淀法制备鱼分离蛋白（fish protein isolates,FPI）和大豆分离蛋白（soybean protein isolats,SPI）,固定蛋白浓度0.5%,在pH 4.0和7.0条件下,高压均质（一级压力30 MPa,二级压力4 MPa）,实验黄原胶（xanthan gum,XG）的添加对FPI、FPI-SPI（质量比2∶1）、FPI-SPI（质量比1∶1）和SPI乳浊体系粒径分布、微观显微结构和乳析指数的影响。结果表明：随着黄原胶的添加（0～0.09%）,乳浊体系平均粒径减小（P〈0.05）;在pH 4.0条件下,乳浊液液滴聚集和絮凝现象明显减少,宏观乳析稳定性提高（P〈0.05）,添加0.06%和0.09%黄原胶的FPI-SPI混合乳浊体系4℃放置10 d都没有明显的分层,而不同比例混合蛋白体系之间的差异不明显（P〉0.05）;在pH 7.0条件下,添加0.06%的黄原胶时,FPI-SPI（质量比2∶1）和FPI-SPI（质量比1∶1）混合乳浊体系微观絮凝现象没有明显改善,宏观乳析稳定性明显提高（P〈0.05）,4℃放置10 d没有明显的分层现象。总体分析,2种蛋白物理混合对乳浊液体系稳定性的改善程度有限,而适量的黄原胶能明显提高酸性条件下体系的乳浊液稳定性。

Fish protein isolates（ FPI） and soy protein isolates（ SPI） were prepared by alkaline solution and isoelectic precipitation. At fixed protein concentration of 0. 5%,pH 4. 0 and 7. 0,the protein emulsion was prepared by high-pressure double-stage homogenization（ 30 MPa and 4MPa）. Xanthan gum amount on the effect for FPI,SPI,FPI-SPI（ 2∶ 1） and FPI-SPI（ 1∶ 1） mixed system as well as the particle size distribution,microstructure and flocculation stability of emulsion was studied. Results showed that the mean particle size of protein emulsion system decreased（ P〈0. 05） with increasing addition of xanthan gum（ 0 ～ 0. 09%）. At pH 4. 0,droplet aggregation and flocculation of emulsion decreased,and stability increased（ P〈0. 05）. No obvious separation was observed for FPI-SPI（ 2 ∶ 1）and FPI-SPI（ 1∶ 1） mixture emulsions with0. 06% and 0. 09% xanthan gum after 10 days stored at 4℃,and as no significant difference between two different ratios of mixture system（ P〉0. 05）. At pH 7. 0,0. 06% of xanthan gum had little improvement on FPI-SPI（ 2∶ 1） and FPI-SPI（ 1 ∶ 1） mixture emulsions,while the stability was increased significantly（ P〈0. 05）,and no obvious separation was found after 10 days at 4 ℃. Results indicated that two proteins FPI SPI mixture had limited improvement on the emulsion stability,while xanthan gum can improve significantly of the emulsion stability at acidic conditions.