Jiangxi Key Laboratory of Natural Products and Functional Food, Jiangxi Agricultural University, Nanchang 330045, China.
Engineering Research Center of Biomass Conversion, Ministry of Education, Nanchang University, Nanchang 330047, China; State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China.
Int J Biol Macromol. 2019 Oct 1;138:116-124. doi: 10.1016/j.ijbiomac.2019.07.057. Epub 2019 Jul 8.
In this paper, the relationship between protein structure changes and in vitro digestion of preserved egg white (PEW) during pickling was studied. Results showed that as the pickling time increased, moisture content of PEW exhibited a decreasing trend, pH value and hardness of PEW exhibited an increasing trend. Environmental Scanning Electron Microscopy (ESEM) revealed that alkali-treated duck egg white could form a more compact gel network structure during pickling. Transmission Electron Microscopy (TEM) showed that PEW consisted of two sorts of structures, namely fibrillar (from 7th to 21st day) and particulate (from 28th to 42nd day). Fourier Transform Infrared (FTIR) spectroscopy showed that there was an increase in the content of β-sheets and a decrease in the content of α-helices during pickling. Protein digestibility of PEW was highest at day 14 and the lowest at day 42. Moreover, the content of β-sheets was negatively correlated with protein digestibility. Peptides identification using LC-MS/MS highlighted that the number of different peptides were positively correlated with the pickling. The number of unique peptides was negatively correlated with protein digestibility at the end of gastric and intestinal digestion. This study would provide guidance for studying nutritional value and controlling quality of preserved eggs.
本研究旨在探讨腌制过程中蛋白结构变化与皮蛋（PEW）体外消化之间的关系。结果表明，随着腌制时间的延长，PEW 的水分含量呈下降趋势，pH 值和硬度呈上升趋势。环境扫描电子显微镜（ESEM）显示，经碱处理的鸭蛋蛋白在腌制过程中可以形成更致密的凝胶网络结构。透射电子显微镜（TEM）表明，PEW 由两种结构组成，即纤维状（第 7 至 21 天）和颗粒状（第 28 至 42 天）。傅里叶变换红外（FTIR）光谱显示，在腌制过程中β-折叠含量增加，α-螺旋含量减少。PEW 的蛋白质消化率在第 14 天最高，在第 42 天最低。此外，β-折叠含量与蛋白质消化率呈负相关。使用 LC-MS/MS 进行肽鉴定突出表明，不同肽的数量与腌制时间呈正相关。胃和肠消化结束时，独特肽的数量与蛋白质消化率呈负相关。本研究可为研究皮蛋的营养价值和质量控制提供指导。
