Structure−Reactivity Relationships of Flavan-3-ols on Product Generation in Aqueous Glucose/Glycine Model Systems

Abstract

Ring structure-reactivity relationships of three flavan-3-ols [epicatechin (EC), epicatechin gallate (ECG), and epigallocatechin gallate (EGCG)] and three simple phenolic compounds (1,3,5-trihydroxybenzene, 1,2,3-trihydroxybenzene, and methylgallate as the analogous individual A, B, and C benzene rings of EGCG) on product generation in an aqueous glucose-glycine reaction model system (125 degrees C and 30 min) were investigated. The addition of EC, ECG, or EGCG to a glucose-glycine model was reported to similarly significantly reduce the formation of pyrazine, methyl-substituted pyrazines, and cyclotene. All three flavan-3-ols were also reported to generate phenolic-C2, C3, C4, and C6 sugar fragment adducts and to statistically reduce the concentration of glyoxal, glycolaldehyde, methylglyoxal, hydroxyacetone, diacetyl, acetoin, and 3-deoxyglucosone during the reaction time course, except for the EGCG reaction where 3-deoxyglucosone was not statistically different from the control after 20 min. For the simple phenolic compounds, methylgallate followed by 1,2,3-trihydroxybenzene was the least reactive, while 1,3,5-trihydroxybenzene was reported as the most reactive phenolic structure for quenching or reducing the concentration of the alpha-hydroxy- and alpha-dicarbonyl sugar fragments during the reaction time course. These results imply that the main mechanism flavan-3-ols reduced product generation was phenolic-sugar fragment carbonyl trapping reactions primarily on the A ring (the meta-polyhydroxylated benzene ring) or not due to the alteration of the reaction reduction potential.

Investigations on the effect of antioxidant type and concentration and model system matrix on acrylamide formation in model Maillard reaction systems

“…A similar carbonyl-trapping property can be attributed to epicatechin gallate, which has also been reported to form adducts with dicarbonyls in model systems (Lo et al, 2006;Noda & Peterson, 2007). The only structural difference between the two flavan-3-ols is located in the Studies in glucose/glycine model systems with added ferulic acid showed that it can undergo decarboxylation, exposing the vinyl group, which could, in turn, undergo various pericyclic reactions with Maillard intermediates (in low moisture conditions) or form adducts with C 2 and C 3 sugar fragments, by electrophilic aromatic substitution reactions (in aqueous model systems) (Jiang, et al, 2009).…”

Stability and anti-glycation properties of intermediate moisture apple products fortified with green tea

“…This reaction also involves ascorbic acid and phenolic degradation (Nicoli, Anese, & Parpinel, 1999). EC and EGCG have been demonstrated to reduce the extent of the Maillard reaction in a glucose-glycine model system (Noda & Peterson, 2007). Similar inhibition could have occurred in GT-fortified apple product.…”

“…Some phenolic extracts can inhibit these reactions (Rudnicki et al, 2007;Ho, Wu, Lin, & Tang, 2010;Tsuji-Naito, Saeki, & Hamano, 2009;. In an aqueous glucose/ glycine model system EC, ECG and EGCG were reported to inhibit glycation by acting through carbonyl trapping, which involves the A-ring (the meta-polyhydroxylated benzene ring) (Noda & Peterson, 2007). In a protein-glucose model system, Nakagawa, Yokozawa, Terasawa, Shu, and Juneja (2002) found that GT catechins containing a gallate moiety at the C-3 position of the C-ring (e.g.…”

Thermal generation or aroma

“…Furthermore, flavonols (Noda and Peterson, 2007) and hydroxycinnamic acids (Jiang et al, 2009) have been shown to alter the progression of the Maillard reaction. Thus, there is an ever-expanding list of components that can be used to manipulate the Maillard reaction, and an understanding of the underlying mechanisms helps to direct the Maillard reaction in the desired direction.…”