Reactive dicarbonyl compounds and 5-(hydroxymethyl)-2-furfural in carbonated beverages containing high fructose corn syrup

α-Dicarbonyl compounds, namely glyoxal (GO), methylglyoxal (MGO) and 3-deoxyglucosone (3-DOG), as well as 5-(hydroxymethyl)-2-furfural (5-HMF) were found and measured in carbonated soft drinks (CSD). It was realized that high fructose corn syrup (HFCS) in regular CSDs was the major source of α-dicarbonyl compounds in beverages after comparison of levels in regular and diet CSDs. In two most commonly used HFCS formulas, 42% and 55% HFCS, the highest level of dicarbonyl found was 3-DOG, followed by MGO, and then GO. The stability of dicarbonyls in CSDs containing HFCS and (−)-epigallocatechin gallate (EGCG) which were incubated at 35 and 45 °C was investigated. It was found that EGCG decreased from 1 mg/mL to 0.5 and 0.3 mg/mL for 35 and 45 °C, respectively, in 16 days storage. Moreover, the reactions of EGCG with MGO, 3-DOG and 5-HMF were observed from the comparison of storage CSDs with and without EGCG under acidic conditions.