典型化学加工条件对不溶性蚕蛹蛋白凝胶特性影响

以鲜蚕蛹为原料分离出不溶性蛋白,对其氨基酸组成进行测定,并采用不同的pH、离子强度以及添加谷氨酰胺转氨酶(transglutaminase,TG酶)处理,对其进行流变学以及拉曼光谱学的分析,探究pH、离子强度以及添加TG酶对不溶性蚕蛹蛋白凝胶特性的影响规律。结果表明,不溶性蚕蛹蛋白中疏水性氨基酸比例达到40%;流变学扫描显示,经过不同pH和离子强度处理后,在pH 5.0~8.0、盐质量浓度为0~35 g/L时,不溶性蚕蛹蛋白凝胶是一种弱凝胶。在pH 6.0、盐质量浓度为35 g/L时体系的G′值和G″值最高,黏弹性最好;pH增大会引起蛋白质结构有序化增多,但不利于蛋白质网络的形成,因此在pH 8.0时的G′值和G″值最低。色氨酸残基在pH 6.0及盐浓度为35 g/L趋于包埋态,酪氨酸残基在pH 6.0及盐质量浓度为35 g/L时暴露最少,此时G′值和G″值最高,推测疏水相互作用和氢键可能是影响不溶性蛋白质凝胶网络的关键作用力。添加TG酶后的体系G′和G″模量明显增大,黏弹性增强。实验结果可为不溶性蚕蛹蛋白的加工提供一定的理论参考。

Effects of typical chemical processing conditions on the gel property of insoluble silkworm pupa protein

The effects of pH,ionic strength and TG enzyme treatment on the gel property of insoluble silkworm pupa protein were investigated.Fresh silkworm pupa was used as raw material to separate insoluble protein,and its amino acid composition was determined.After the treatment with different pH,ionic strength and TG enzyme,it was measured by rheology and Raman spectroscopy.The results showed that the hydrophobic amino acid ratio of insoluble silkworm pupa protein reached 40%.Rheological scanning showed that the insoluble silkworm pupa protein gel was a weak gel in the range of pH 5.0-8.0 and salt concentration 0-35 g/L after different pH and ionic strength treatment.And the G′value and G″value of the system were the highest,and the viscoelasticity was the best with the treatment of pH 6.0 and salt concentration was adjusted to 35 g/L.Moreover,the increases of pH led to the increase of protein structure ordering,but was not conducive to the formation of protein network.So G′value and G″value were the lowest at pH 8.0.Tryptophan residues tended to be embedded at pH 6.0 and 35 g/L salt concentration,while tyrosine residues were exposed at least at pH 6.0 and 35 g/L salt concentration,and G′and G″values were the highest.After adding TG enzyme,the modulus of G′and G″of the system increased obviously,and the viscoelasticity was enhanced.The experimental results could provide a theoretical reference for the processing suitability of insoluble silkworm pupa protein.