食品科学 ›› 2020, Vol. 41 ›› Issue (22): 15-21.doi: 10.7506/spkx1002-6630-20190906-080

• 食品化学 • 上一篇    下一篇

pH值处理对黑豆分离蛋白结构、流变特性及乳化性能的影响

曾琪,胡淼,王欢,钟明明,齐宝坤,江连洲   

  1. (东北农业大学食品学院,黑龙江 哈尔滨 150030)
  • 出版日期:2020-11-25 发布日期:2020-11-26
  • 基金资助:
    黑龙江省自然基金联合引导项目(LH2019C032)

Effect of pH Treatment on Structure, Rheological Properties and Emulsifying Properties of Black Bean Protein Isolate

ZENG Qi, HU Miao, WANG Huan, ZHONG Mingming, QI Baokun, JIANG Lianzhou   

  1. (College of Food Science, Northeast Agricultural University, Harbin 150030, China)
  • Online:2020-11-25 Published:2020-11-26

摘要: 以黑豆为原料,将碱溶酸沉得到的黑豆分离蛋白(black bean protein isolate,BBPI)用不同pH值条件(2.0~11.0)处理2 h,然后恢复到中性条件,测定处理后BBPI的表面疏水性、溶解度、二级结构、三级结构、乳化稳定性及流变学性质。结果表明:pH 5.0处理的蛋白质具有最低的溶解度和乳化稳定性,远离pH 5.0处理的样品溶解度、乳化稳定性均呈现上升趋势且碱性处理条件下溶解度、乳化稳定性更好;随酸碱度的增加,蛋白质三级结构展开程度加大,二级结构发生β-折叠向α-螺旋的转变,高溶解性的蛋白质表面疏水性低且表面疏水性与β-折叠含量正相关,与β-转角负相关。在剪切速率0.1~100 s-1的范围内表观黏度随着剪切速率的增加逐渐下降,乳液呈剪切稀释,随着pH值的增加,表观黏度先减少后增大;动态流变学分析结果表明,不同pH值处理的BBPI乳液在角频率为0~70 rad/s时,弹性模量G’随角频率的增加而呈现上升趋势,pH 3.0时蛋白质具有更强的界面黏弹性,形成的乳液界面流变学性质更好,pH 11.0时蛋白质有利于更好的与油水界面结合,乳化性能最好。

关键词: 黑豆分离蛋白;pH值;表面疏水性;流变特性;乳化性能

Abstract: Black bean protein isolate (BBPI), obtained by alkali solution and acid precipitation, was treated under different pH conditions (2.0–11.0) for 2 h and then returned to neutral pH condition. The surface hydrophobicity, solubility, secondary and tertiary structures, emulsion stability and rheological properties of BBPI were determined. The results showed that the protein sample treated at pH 5.0 had the lowest solubility and emulsion stability, while that treated at pH values far from 5.0 showed an increasing trend in solubility and emulsion stability, which were better under alkaline conditions. With the increase in acid and alkaline intensity, the unfolding degree of protein tertiary structures increased, and the β-sheet secondary structure transformed to α-helix. The higher the solubility, the lower surface hydrophobicity, which was positively correlated with the β-sheet content but negatively correlated with the β-turn content. With increasing the shear rate from 0.1 to 100 s-1, the apparent viscosity gradually decreased, and the emulsion showed a shear-thinning behavior; with the increase in pH, the apparent viscosity initially decreased and then increased. The dynamic rheological analysis showed that with the increase in angular frequency from 0 to 70 rad/s, the G’ of emulsions stabilized by BBPI treated with different pH values increased. At pH 3.0, the protein had stronger interface viscoelasticity, and the formed emulsion had better interfacial rheological properties. At pH 11.0, the protein was conducive to better oil-water interfacial combination, and displayed the best emulsifying performance.

Key words: black bean protein isolate; pH; surface hydrophobicity; rheological behavior; emulsifying properties

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