Sheep milk proteins: current research on nutritional characteristics, biofunctional properties, and application...

Sheep milk proteins (SMPs) are key nutritional and functional components of sheep milk and have attracted increasing interest because of their high digestibility, distinctive compositional profile, and reported bioactivities. Compared with bovine milk proteins, SMPs contain a high proportion of β-casein, relatively low αs1-casein, and multiple low-abundance bioactive proteins and peptides. However, their high value utilization remains limited by uneven global milk supply, raw-material variability, challenges in separation and purification, and insufficient in vivo and clinical evidence.

This review focuses specifically on sheep milk proteins as nutritional, structural, functional, and industrial. It summarizes sheep milk production, SMP composition and nutrition, and factors affecting SMP yield and quality, including breed, lactation stage, parity, genotype, season, and nutritional status. Enrichment, separation, purification, and identification strategies are critically evaluated, together with reported bioactivities and food related application potential.

SMPs are promising multifunctional ingredients for dairy innovation, infant nutrition, and bio-based food materials. Their value should not be inferred from protein abundance alone, but from the combined effects of protein composition, casein micelle structure, digestion-derived peptide release, bioaccessibility, and processing feasibility. However, translation remains constrained by inconsistent raw-material supply, compositional variation, limited structure and activity understanding, and the predominance of preclinical evidence. Future studies should prioritize ACE-inhibitory and DPP-IV-inhibitory sheep milk peptides by validating their structure activity relationships, bioavailability, and in vivo mechanisms in relevant cardiometabolic models.