Strategic Modification of Scallop Mantle Protein Isolates via Alkaline Extraction: Resource Utilization of Biological Waste

Scallop mantle, an abundant yet underutilized processing byproduct, holds vast potential for high-value valorization, yet its restricted functional versatility hinders food-grade application. This study systematically analyzed the molecular mechanisms governing the characteristic evolution (physicochemical, structural, and functional) of scallop mantle protein isolates (SMPIs) subjected to alkaline extraction (pH 8–12). Results indicated that extraction pH from 8 to 12 dramatically boosted the yield of SMPIs from 5.01% to 96.29% and increased purity (reaching 96.01% at pH 10.0 before plateauing), alongside increased particle size and surface hydrophobicity, but caused a dark yellow appearance at pH 12. During this process, proteins gradually degraded into small peptide fragments, with α-helix progressively transforming into β-sheet structures. The exposed hydrophobic residues and altered surface charges substantially modulated aggregation, generating highly uniform and dense microstructures at elevated pH. Notably, SMPIs exhibited optimal water absorption capacity, emulsifying stability index (ESI), and foaming stability at extraction pH 10. SMPIs demonstrated superior performance in thermal stability and foaming ability at extraction pH 11. At extraction pH 8, the stable conformation of SMPIs conferred the highest solubility and superior oil absorption capacity. Our research findings will facilitate the utilization of scallop mantle as a customizable resource for specific functionalities under the waste-to-wealth paradigm.