热加工对鸡蛋中4种主要过敏原结构的影响

为探究热加工对鸡蛋主要过敏原结构的影响,对鸡蛋清中的4种过敏原进行不同条件的热加工,并利用圆二色光谱、紫外-可见光光谱、外源荧光光谱对加热前后过敏原的空间结构进行表征。结果表明,卵转铁蛋白对热不稳定,随加热时间的延长和温度的升高,分子结构逐渐展开,芳香族残基和疏水基团暴露于分子表面;轻微加热使卵白蛋白分子的二级结构更加有序,吸光度减小,表面疏水性增大,随着加热程度的增大,其二级结构变得无序,分子发生聚集;加热后卵类黏蛋白的二级结构较为稳定,轻微加热其分子展开,吸光度和荧光强度增大,继续加热使蛋白分子部分聚集;热处理使溶菌酶分子的有序性下降,芳香族残基和疏水基团逐渐暴露,但随着加热程度的增加,蛋白分子发生部分聚集。本实验结果为后续研究加热对鸡蛋过敏原致敏性的影响提供理论依据。

Effect of Thermal Processing on Structure of Four Major Egg White Allergens

In order to explore the impact of thermal processing on the structure of egg white allergens, four major allergens in hen’s egg white were heated under different conditions of temperature and time. Circular dichroism, ultraviolet and fluorescence spectroscopy were used to detect the spatial structure of allergens. Results showed that ovotransferrin was unstable to heat, and its molecular structure was unfolded, with the aromatic residues and hydrophobic groups exposed on the molecular surface after heating. The secondary structure of ovalbumin became more ordered, ultraviolet absorbance value decreased, and surface hydrophobicity increased when it was heated slightly; however, with increasing temperature and heating time, ovalbumin became unordered and aggregated. The secondary structure of ovomucoid was relatively stable, and its molecules were unfolded after mild heating, leading to increased absorption and fluorescence intensities, and then aggregated partly after further heating. The secondary structure of lysozyme became disordered with the aromatic residues and hydrophobic groups gradually exposed after heating, but with increasing degree of heating, part of lysozyme became aggregated. The present study may provide a theoretical basis for studying the effect of heating on the allergenicity of egg allergens.