Thiamine in Lipid Systems vs. the Antioxidant Activity of Epigallocatechin Gallate and Caffeine

Abstract

The aim of this study was to determine correlations between the concentration of thiamine hydrochloride or thiamine pyrophosphate and the antioxidant activity of epigallocatechin gallate (EGCG) and caffeine, as well as thiamine stability. The study was conducted in model systems. Oxidation degree indices of soybean oil (peroxide value and anisidine value LAN) and concentrations of total thiamine were determined. To compare the dynamics of the changes in thiamine content during storage, half-life T1/2 was determined. There was a strong correlation between the stability of thiamine and the stability of the oil. Thiamine was particularly sensitive to secondary oxidation products. Higher losses of thiamine introduced in the form of thiamine pyrophosphate were found (4–6%). The addition of tea components increased fat stability and thus reduced thiamine losses. The dynamics of thiamine loss were found to be lower with EGCG than caffeine. The antioxidant activity of these components was significantly reduced when the content of thiamine (1.0–20.0 mg/100 g) was higher than the natural level in foods. In order to maintain thiamine stability and the high activity of the active tea ingredients, it is necessary to consider their simultaneous addition to the systems in concentrations that limit their interactions.