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Ovalbumin (OVA) is one of the major food allergens in hen eggs. In this work, it was demonstrated that glycation with d-glucose and its epimers, including d-mannose, d-allose, d-galactose, and l-idose, could effectively attenuate the IgG/IgE binding of OVA, which was attributed to the covalent masking by sugars and to its structural changes. The glycation sites were determined, and their average degree of substitution was found using liquid chromatography coupled with high-resolution mass spectrometry. Fluctuations in OVA conformation were monitored by conventional spectrometry. Compared to those of OVA-Man and OVA-Glu, OVA-All, OVA-Gal, and OVA-Ido showed a higher glycation extent, and the alterations on their steric layouts were more drastic, suggesting that the configuration of hydroxyl groups at positions C-3, C-4, and C-5 in sugars might be important for the glycation reactivity; as such, their capabilities in binding with IgG/IgE decreased more significantly. Attempts were made to provide valuable information for in-depth understanding of the differences in biochemical functionality among epimeric sugars. These insights would be helpful for designing sweetened food products with a desirable level of safety.

Parvalbumin (PV) is one of the major allergens in fish. The aim of our present work was to research the influence mechanism of glycation with different reducing sugars (glucose, fructose, ribose, lactose, and galactose) on the immunoglobulin E (IgE) and immunoglobulin G (IgG) binding capacity and structure changes of PV in Alaska Pollock. PV glycated with glucose or fructose (PV-Glu/ PV-Fru) exhibited the higher IgE/IgG binding capacities than that of ribose, galactose, or lactose. During glycation, the lysine (Lyr), tyrosine (Tyr), and phenylalanine (Phe) of PV were gradually embed into core area of three-dimensional structure of protein, which reflected in the ultraviolet (UV) spectrum and fluorescence spectra. Moreover, the increase of surface hydrophobicity had confirmed the conformation alteration of glycated PV. These results suggest that there is a specific association among the change of PV in glycation and in potential allergenicity. The types and conformation of reducing sugar greatly influenced the IgE/IgG binding capacity of PV, and glycation with ribose and galactose was a promising approach for reducing the IgE/IgG binding capacity of PV from Alaska Pollock. PRACTICAL APPLICATIONS: Parvalbumin (PV), the major allergen of fish, it can not only maintain the physiological activity of cells, but also cross react with human amyloid protein to alleviate Alzheimer's disease and Parkinson's syndrome. This study revealed that the IgE/IgG binding capacity and structural changes of PV from Alaska Pollock modified by glycation with different reducing sugars. This will help us to understand the sensitization and structural change of the glycated products after the reaction of PV with different reducing sugars. It provides an effective carbonyl source for the preparation of low antigenicity PV based on glycation and lays a foundation for glycation modification of other food allergens.