Structure and IgE-binding properties of α-casein treated by high hydrostatic pressure, UV-C, and far-IR radiations

alpha-Casein was treated by high hydrostatic pressure (HHP), UV-C, or far-IR (FIR). These treatments increased roughness, alpha-helicity, and beta-turn, but decreased beta-sheet and IgE-binding reactivity. One 5-min cycle at 600-MPa pressure caused maximum alpha-helicity, beta-turn, and surface hydrophobicity (Ho), but minimum stimulated intestinal fluid from alpha-casein. UV-C (15 min) produced the maximum kurtosis, free sulfhydryl content (FSC), and stimulated intestinal fluid, minimum Ho, R, and simulated gastric fluid. FIR (15 min) caused the minimum alpha-helicity and FSC, but maximum R and beta-sheet. The NMR peaks of the main allergenic characteristics affected were 15-17, 23-26, 40, 53, 59 and 85-88, respectively. Generally, all treatments decreased the allergenicity of alpha-casein by modifying its morphology, ultrastructure, characteristic domains, and peptides. Based on the stimulated digestion tests, UV-C (15 min) was more efficient for lowering alpha-casein allergenicity, thus decreasing the allergenicity of milk. (C) 2016 Elsevier Ltd. All rights reserved.