热处理羊乳酪蛋白结构与抗原性的变化规律

热加工处理羊乳 α-酪蛋白(α-casein,α-CN)和 β-酪蛋白(β-casein,β-CN),通过圆二色谱、荧光光谱等方法探索不同热加工条件下羊乳的蛋白结构变化与抗原性的关系.结果表明:随着对蛋白热处理温度的升高,会破坏羊α-CN和β-CN的天然结构,使得分子内部发生交联或聚集,导致分子量发生改变,分子内游离羰...

The Correlation between Structural and Antigenicity Changes of Goat Casein by Heat Treatment

The heat treatment ofα-casein(α-CN)andβ-casein(β-CN)in goat milk was explored by circular dichroism,fluorescence spectroscopy and other methods to analyze the effects of their structure and antigenicity.The results showed that with the increase of the heat treatment temperature of the casein,the natural structure ofα-CN andβ-CN was destroyed,caused molecular cross-linking or aggregation,and changed the molecular weight.The content of free carbonyl in the molecule increased.At 134℃,the carbonyl content increased by 134.72%and 110.98%,respectively.The free sulfhydryl content decreased continuously.The maximum fluorescence absorption intensity of the hydrophobic probes increased by 50.38%,and 9.61%,respectively.The temperature rise caused hydrophobic groups or disulfide bonds to be exposed,resulting in increasing hydrophobicity of the proteins.Circular dichroism results showed that the degree of curl or elastic structure in the secondary structure undergoes complex transformation,which changes the spatial structure of the protein.α-spirals were increased,β-turns and irregular curls were decreased.The antigenicity of casein decreased with increased temperature.After simulated gastrointestinal digestion,the antigenicity was reduced by 80.63%and 84.12%,respectively,at 134℃.Therefore,heat treatment can reduce the antigenicity of goat milk casein.And the change of antigenicity are inversely proportional to the change of free carbonyl content of protein.In addition,it is also positively correlated with the content of irregular curls andβ-turns in the secondary structure.