Mechanisms of saccharide protection against epigallocatechin-3-gallate deterioration in aqueous solutions

We investigated the mechanisms of the protection conferred by sugars to epigallocatechin-3-gallate (EGCG) against deterioration. Additionally, we present a rapid method for evaluating the deterioration rate of EGCG using absorbance spectroscopy. We found that various sugars provided different levels of protection at identical weight percentage, and the combination of sugars and β-lactoglobulin nanocomplexes provided greater protection for EGCG than each protective component alone. We suggest that the concentration-dependent protection by sugars resulted from a combination of mechanisms, including: (1) reduced aqueous O₂ solubility, (2) scavenging of reactive oxygen species, and (3) chelation of traces of transition metal ions, which is suggested to be the main reason for the differences among the sugars. The observed protective effect of sugars can be easily applied by the industry in proper selection of sugars for enrichment of syrups or concentrates with EGCG and for the preparation of enriched beverages and foods for health promotion.