具有DPPH自由基抑制活性的蚕蛹蛋白酶解液脱色工艺优化

利用木瓜蛋白酶水解的蚕蛹蛋白酶解液作为研究原料，根据响应面试验设计方法，以脱色率和1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl，DPPH）自由基清除保持率作为响应面指标，得最佳脱色工艺条件为：活性白土、碱性钙基膨润土和膨润土按照质量比1∶1∶1混合为脱色剂、脱色剂用量1.9%、酶解液质量浓度9.61 mg/mL、pH 7.2、水浴温度60 ℃、振荡转速150 r/min、脱色时间1.0 h。在此条件下实验，得出DPPH自由基清除保持率84.5%、脱色率94.5%，与预测值相比误差值均小于5%，说明采用响应面试验设计方法对蚕蛹蛋白酶解液脱色体系进行优化具有较好的可靠性。最后再对脱色前后酶解液中各氨基酸含量进行比较，发现经脱色处理后酶解液中对DPPH自由基抑制有显著作用的疏水性氨基酸和芳香族氨基酸含量减少。

Decolorization of Silkworm Pupae Protein Hydrolyzate with DPPH Radical Scavenging Activity

Papain hydrolyzate of silkworm pupae protein with DPPH radical scavenging activity was decolorized by the
combined use of activated clay, alkaline Ca-bentonite and bentonite. Based on decolorization efficiency and retention rate of
radical scavenging activity, the decolorization conditions were optimized by using single-factor design and central composite
design (CCD) coupled with response surface methodology (RSM). When the hydrolyzate with a concentration of 9.61 mg/mL
and an initial pH of 7.2 was added with activated clay:alkaline Ca-bentonite:bentonite (1:1:1) in a proportion of 1.9% and
incubated for 1.0 h in a thermostatically controlled water at 60 ℃ with shaking at a speed of 150 r/min, it retained 84.5%
of its original DPPH radical scavenging activity and the decolorization rate was 94.5%, both close to the predicted values
with a relative error less than 5%, suggesting the reliability of the developed response surface model. Comparing the amino
acid composition of the decolorized hydrolyzate with that of the untreated one, it was found that the contents of
hydrophobic and aromatic amino acids which are significantly effective in inhibiting DPPH free radical were reduced
after the decolorization treatment.