Residual allergenicity in commercial partially and extensively hydrolyzed infant formulas: A combined immunological and mass spectrometric study.

Hypoallergenic infant formulas are widely used for dietary management of cow's milk allergy in infants, yet reliable assessment of residual allergenicity remains important. This study combined immunological assays with high-resolution peptidomics to evaluate the residual allergenicity of partially hydrolyzed (PHF) and extensively hydrolyzed (EHF) products registered as Foods for Special Medical Purposes in China. A laboratory-scale whey protein hydrolysate (WPH) was also prepared for comparison of hydrolysis efficiency and epitope resistance. The PHFs showed marked heterogeneity, with degree of hydrolysis (DH) values below 28% and several products retaining intact allergenic proteins and IgE-binding reactivity. The EHFs showed higher DH values ranging from 36.6% to 83.7%, but β-lactoglobulin-derived epitopes, including regions 108-116, 118-140 and 165-178, persisted across commercial EHFs and laboratory WPH. These findings indicate that epitope-level analysis can complement conventional hydrolysis parameters in assessing residual allergenicity of hydrolyzed infant formulas.