蛋壳胶护膜研究进展

蛋产品安全一直是人们重点关注的问题，也是研究的热点。随着福利养殖的推广，鸡蛋被微生物污染的机率增大。除了加强饲养管理之外，强化鸡蛋自身保护屏障从而抵抗细菌入侵也十分重要。胶护膜是蛋壳最外层覆盖的无色透明膜，鸡蛋产出前1.5~2.0 h于子宫部形成，是蛋抵御微生物污染的重要屏障，研究表明胶护膜较厚的蛋不易被细菌入侵。鸡蛋蛋壳胶护膜主要由糖蛋白（90%）、多糖（4%）、脂质（3%）和以羟基磷灰石晶体形式存在的无机磷（3%）组成。胶护膜中含有溶菌酶C、卵转铁蛋白、ovocleidin-32等多种抗菌蛋白，可有效地阻碍细菌跨壳污染。此外，胶护膜能终止蛋壳矿化、帮助蛋产出前在子宫中翻转、调节水气交换以延长鸡蛋的保存时间。本文对胶护膜的结构、生物学功能、胶护膜品质评价方法及胶护膜质量的影响因素等方面进行了阐述，并对尚待解决的问题展开了探讨。

Research Progress on Eggshell Cuticle

The safety of egg product which causes public concern is always the hotspot of research. As the popularization of welfare poultry rearing, the chance of eggs being contaminated by microorganisms increases. In addition to strengthen feeding management, it is also important to strengthen the egg's own protective barrier to resist bacterial invasion. The cuticle, an invisible layer on the surface of eggshell, is formed in the uterus at 1.5-2.0 h before oviposition. The cuticle is a natural defense preventing microorganism penetration across the eggshell. It was reported that eggs with thicker cuticle had a lower bacteria penetration rate compared with the eggs with thin cuticle layer. The eggs' cuticle is mainly composed of glycoprotein (90%), polysaccharides (4%), lipids (3%) and inorganic phosphorus in the form of hydroxyapatite crystals (3%). The eggshell cuticle contains several antimicrobial proteins, like lysozyme C, ovotransferrin, ovocalyxin-32, which can prevent bacterial trans-shell penetration effectively. Moreover, the cuticle also has many other functions:termination of calcite crystal growth during shell formation, as a lubricant to facilitate egg rotation in the uterus, extension the eggs' storage time by regulating the exchange of water and air. In this paper, the structure, biological function, evaluation method and factors affecting the quality of cuticle are reviewed, and the existed problems are discussed.