Osborne fractionation of pomegranate seed protein: Structural characteristics, processing properties, proteomic...

Pomegranate seeds constitute over 50% of juice-processing pomace and represent an underutilized sustainable plant protein source. This study compared albumin (ALB), globulin (GLO), prolamin (PRO), glutelin (GLU), and crude protein (CP) fractions of pomegranate seed protein. ALB exhibited the highest solubility (24.32%) and essential amino acid index (15.24%) with the lowest trypsin inhibition rate (5.08%), indicating superior hydration and nutritional potential. PRO showed the highest surface hydrophobicity (472.62), strongest oil-holding capacity and emulsion stability, the highest intestinal digestibility (21.18%), and the lowest phytic acid content (1.03 μmol/g). GLU exhibited the highest zeta potential (-30.14 mV), thermal stability (Td 163.2 °C; ΔH 201.65 J/g), and foaming performance. Correlation analysis linked secondary structure and surface hydrophobicity with thermal stability, oil binding, emulsification, and digestibility. Data-independent acquisition mass spectrometry revealed fraction-specific enrichment of storage, lipid-transfer-related, and metabolic proteins. These findings demonstrate structure-function differentiation among PSP fractions and support their targeted food applications.