鸡蛋蛋壳膜超微结构与呼吸强度的相关关系

Correlation between eggshell membrane ultrastructure and respiration intensity

蛋壳膜作为蛋壳的有机层是呼吸的必经通道,研究蛋壳膜的超微结构与鸡蛋呼吸强度的相关关系对于鸡蛋贮藏保鲜具有重大意义。该研究利用扫描电子显微镜(Scanning Electron Microscope,SEM)对蛋壳膜的超微结构图像进行表征。结果表明:强呼吸强度(≥3 mg/(kg·h))与弱呼吸强度(≤1 mg/(kg·h))鸡蛋的蛋壳膜纤维直径、孔隙度与厚度均存在显著性差异(P<0.05);鸡蛋蛋壳膜纤维直径、外膜以及内膜外侧的孔隙度与呼吸强度存在极显著的正相关关系(P<0.01),蛋壳膜厚度与呼吸强度存在极显著的负相关关系(P<0.01)。蛋壳膜外膜纤维直径大于内膜,厚度为内膜的3~4倍。以蛋壳膜外膜外侧孔隙度、外膜内侧孔隙度、内膜外侧孔隙度、内膜内侧孔隙度、外膜外侧纤维直径、外膜内侧纤维直径、内膜外侧纤维直径、内膜内侧纤维直径与外膜厚度、内膜厚度共10个指标特征参数为自变量,鸡蛋呼吸强度为因变量,建立较佳偏最小二乘回归模型,测试集相关系数为0.9767,蛋壳膜超微结构可以很好地表征呼吸强度的大小;以弱、中与强呼吸强度作为分类依据,建立了偏最小二乘判别分析,测试集准确率为83.33%,说明在25℃空气环境下蛋壳膜超微结构对呼吸强度具有较好的判别效果。研究结果为更好地利用蛋壳膜超微结构特性来改良涂膜保鲜技术提供参考。

Eggshell is a highly ordered and mineralized structure for egg respiration. The shell membrane with the organic layer has been one of the most important eggshell ultrastructures for the necessary channel of egg respiration. It is a high demand to determine the relationship between the ultrastructure of the eggshell membrane and the respiration intensity for the preservation and storage of eggs. In this research,the ultrastructure morphology of eggshell membranes was first characterized by a Scanning Electron Microscope(SEM). An image processing software was then utilized to extract the structural parameters from the ultrastructure image of the eggshell membrane. Therefore, a correlation model was established for the fiber diameter, porosity, the thickness of eggshell membranes, and the respiration intensity of the egg. The result showed that there was a significant difference between the strong(≥3 mg/(kg·h)) and weak(≤1 mg/(kg·h)) respiration intensity with the fiber diameter, porosity, and the thickness of the eggshell membranes. Specifically, there was a very significant positive correlation between the fiber diameter, the porosity of eggshell membranes, and the respiration intensity(P<0.01), whereas, a very significant negative correlation between the thickness of the eggshell membranes, and the respiration intensity of the egg(P<0.01). The membrane fibers were disorderly and tightly arranged in the eggshell ultrastructure under the strong respiration intensity. There were outstanding mucopolysaccharide tumor-like attachments on the outer membrane of eggs under the weak and medium respiration strength, whereas, the granular attachments on the eggs under the strong respiration strength. The fiber diameter of the outer eggshell membrane was larger than that of the inner, and the thickness of the outer eggshell membrane was 3-4 times that of the inner. The fibers of the inner eggshell membrane presented more slender and straighter than those of the outer. A partial least squares regression model was established, where the 10 characteristic parameters of porosity, fiber diameter, and thickness on both sides of the eggshell membrane were taken as the independent variables, and the egg breathing intensity as the dependent variable, as well as the correlation coefficient RP was 0.976 7. It was found that the ultrastructure of the eggshell membrane was used to better characterize the respiration intensity. A partial least square discriminant analysis was also conducted to take the respiration intensity as the classification, where the accuracy of the test set was 83.33%. The outer surface porosity on the outside of the outer membrane, the fiber diameter on the outside of the inner membrane, the thickness of the outer membrane, and the fiber diameter on the inside of the outer membrane greatly contributed to distinguish between different respiratory intensities. Among them, the porosity of the outer membrane was attributed to the great respiratory intensity. Consequently, the ultrastructure of the eggshell membrane posed better discrimination on the respiration intensity of fresh eggs in an air environment of 25℃. The finding can also offer a promising prospect for the storage and preservation of eggs, particularly for the protein extraction of eggshell membranes.