Soluble Proteins From Conventional and Organic Eggshell Membranes With Different Proteomic Profiles Show Similar In Vitro Biofunctions

The eggshell membrane (ESM), resembling the extracellular matrix (ECM), acts as a protective barrier against bacterial invasion and offers various biofunctions due to its porous structure and protein-rich composition, such as ovalbumin, ovotransferrin, collagen, soluble protein, and antimicrobial proteins. However, the structure of ESM primarily comprises disulfide bonds and heterochains, which poses a challenge for protein solubilization/extraction. Therefore, the method of dissolving and extracting bioactive protein components from ESM has significant potential value and importance for exploring the reuse of egg waste and environmental protection. In this study, soluble ESM proteins (SEPs) were extracted from conventional (industrial-fed) and organic (free-grounded) using an acidic 3-mercaptopropionic acid (3-MPA) extraction strategy. FTIR was employed to monitor the chemical changes in the ESM, while LC-MS/MS was used to conduct the proteomic analysis. The biocompatibility and effects of SEP cocktails on ECM synthesis were also investigated. The results indicated that the acidic 3-MPA strategy effectively altered the ESM chemical composition, thereby facilitating SEPs extraction. The SEPs from conventional and organic eggs have different protein profiles but with partial overlapping. SEPs from both sources showed similar desirable biosafety profiles and dose-dependent promotion of osteoblastic (ECM) component synthesis, suggesting that different egg sources may contribute to consistent core biological functions of protein products, they may also introduce different functional priorities.