Abstract: To investigate the effect of thermal processing on the conformation and antigenicity of bovine milk αs1-casein, the changes in the immunogenicity of αs1-casein under different heating conditions were analyzed by indirect competitive enzyme immunosorbent assay (icELISA) and Western blotting (WB) methods, and then the secondary structure changes were analyzed by fluorescence spectroscopy using 8-anilino-1-naphthalenesulfonic acid (ANS) as a probe and circular dichroism spectroscopy to preliminarily reveal the regulatory mechanism of heat treatment on the antigenicity of αs1-casein. The results showed that the α-helix content of αs1-casein significantly decreased after treatment at 80 ℃ for 60 min, 90 ℃ for 10 min or 90 ℃ for 60 min compared with the untreated control, whereas the random coil content increased significantly after treatment at 70 ℃ for 20 min, 80 ℃ for 20 min or 90 ℃ for 20 min. The surface flourescence intensity was the strongest after heating treatment at 70-100 ℃ for 20 min, while the secondary structure changes were not significant under other heating conditions. The conformational changes of αs1-casein led to a significant decrease in the antigenicity of αs1-casein. The icELISA showed that the residual antigenicity of αs1-casein was the highest after heating treatment at 70-100 ℃ for 20 min, while the WB results showed that αs1-casein still had immunoreactive properties under all heating conditions. It is suggested to further reveal the regulatory mechanism of heat treatment on the antigenicity of αs1-casein through animal tests.

Key words: αs1-casein; allergen; thermal processing; antigenicity; secondary structure

摘要： 为探究热加工方式对牛乳过敏原αs1-酪蛋白构象和抗原性的影响，利用间接竞争酶联免疫吸附测定方法、 免疫印迹方法分析不同加热条件下αs1-酪蛋白免疫原性的变化，进而通过8-苯胺-1-萘磺酸荧光探针和圆二色谱分 析其二级结构变化，初步揭示热处理调控过敏原αs1-酪蛋白抗原性的机制。结果表明：在80 ℃、60 min，90 ℃、 10 min，90 ℃、60 min条件下热处理后，αs1-酪蛋白中α-螺旋结构含量显著低于未加热αs1-酪蛋白，在70 ℃、 20 min，80 ℃、20 min，90 ℃、20 min条件下热处理后，αs1-酪蛋白中无规卷曲含量显著增加，70～100 ℃加热 20 min条件下表面荧光强度最强，其他温度-时间条件下二级结构含量变化不显著；αs1-酪蛋白构象的变化导致αs1-酪 蛋白的抗原性显著降低，间接竞争酶联免疫吸附测定显示，在70～100 ℃加热20 min条件下，αs1-酪蛋白的抗原残留 量均较高，而免疫印迹方法显示不同温度-时间条件下αs1-酪蛋白仍具有免疫反应特性，建议进一步通过动物实验揭 示热处理调控αs1-酪蛋白抗原性的机制。

关键词: αs1-酪蛋白；过敏原；热加工；抗原性；二级结构