基于低场核磁共振技术的咸鸭蛋腌制过程水分及质构特性变化

Study on changes of gel moisture characteristic and texture properties of duck eggs during salting period by low-field nuclear magnetic resonance

运用低场核磁技术测定腌制过程中蛋清和蛋黄中水分的横向弛豫时间(T_2)和信号强度,并表征蛋清和蛋黄中水分的迁移过程,同时结合蛋清和蛋黄的含水率、含盐量和质构特性分析了盐离子对咸鸭蛋品质的影响。结果显示:在腌制过程中,蛋清和蛋黄中的水分不断向外迁移,水分含量显著降低(P<0.05),蛋清中水分的T_2显著增加(P<0.05),表明蛋清中不同类型水分受到的束缚力降低,水分的自由度增大,其中T_(22)相对降低,T_(23)相对增加,质构指标(硬度、弹性、内聚性和咀嚼性)显著降低(P<0.05),持水力前期显著降低(P<0.05),后期略有增加;随着鸭蛋内盐分含量的显著增加(P<0.05),蛋黄中不同类型的水分的T_2显著降低(P<0.05),蛋黄中的成分结合的更加紧密,硬度、内聚性和咀嚼性显著增加(P<0.05),而弹性却显著降低(P<0.05)。应用低场核共振磁技术对咸鸭蛋状态及水分含量的测定可以作为预测咸鸭蛋成熟度和品质的参考指标。

In order to explore the effects of salt ions on gel texture properties and moisture characteristic of duck eggs,low field nuclear magnetic resonance(Low-field NMR)was integrated to analyze the changes of the moisture status.Water relaxation time(T2),proton density and relaxation area(A2)were explored by magnetic resonance spectroscopy(MRS),and water distribution was visualized by MRI.Meanwhile,the differences in traditional characteristic indices of gels such as texture properties(hardness,springiness,cohesiveness and chewiness)were also investigated.The results showed that the relative proportions of free water increased,and the relative proportions of immobilized water and bound water decreased.T2 transverse relaxation time of yolk decreased significantly(P<0.05),and the water of yolk was bound stronger and its degree of freedom decreased.According to the data of texture analyzer,the hardness,springiness,cohesiveness and chewiness of the album gel decreased significantly(P<0.05)and water holding capacity decreased significantly(P<0.05)at first and increased slightly at last.The hardness,cohesiveness and chewiness of yolk increased significantly(P<0.05),while the springiness decreased significantly(P<0.05).This study provides a theoretical reference for the application of Low-field NMR to analyze the correlation between gel strength and moisture characteristic of duck eggs during salting period.