Alcalase and neutrase hydrolyzed egg yolk powder (ANEYP) and alcalase and papain hydrolyzed egg yolk powder (APEYP) were prepared by bi-enzyme hydrolysis to investigate hydrolysis effects on immunoenhancing properties compared with egg yolk powder (EYP). The properties were then compared with EYP, including their structure, in vitro digestion characteristics, and immunomodulatory activity. Hydrolysis induced conformational changes: shifted secondary structures from α-helix/β-sheet to β-turn/random coil., accompanied by reduced protein molecular weight. Notably, ANEYP exhibited a higher degree of hydrolysis (17.22±1.23%) and digestibility (87.15±3.15%) compared to APEYP. Furthermore, the digestion process resulted in the release of greater amounts of free amino acids (FAAs), including Val, Leu, and Phe indicating ANEYP's greater immunostimulatory potential. In cyclophosphamide-induced immunosuppressed mouse, ANEYP administration significantly alleviated immune organ atrophy and weight loss, improved thymus/spleen indices, and elevated serum IgM, IgG, HC50, and hemolysin levels. Correlation analysis confirmed that Leu and Val release, alongside digestibility, were strongly associated with immunomodulatory activity (r = 0.99, p < 0.001). These findings demonstrate that ANEYP outperforms APEYP and EYP, offering superior non-specific and specific immune enhancement.
Zhang et al. (Mon,) studied this question.