## 3 Results and Discussion
### Use of Phenolic Compounds to Inhibit or Block the Maillard Reaction in Bakery Products
#### 3.5.1. Bread
Purple corn flour is also rich in flavonoids, and the high levels of flavonoids may prevent free-fluorescent-AGE formation because any tetrahydroxyl and hexahydroyl groups in their structures can protect against the oxidation of free thiol groups in proteins via the formation of monothiol, dithiol, and trithiol adducts. Finally, some phenolic acids contained in purple corn flour (i.e., ferulic, p-coumaric, malvidin) and the total phenolic compound content correlated negatively with free fluorescent AGEs, indicating that they might show antiglycative behavior. The concentration of 3-DG ranged from 376.65 mg/kg crust in the GF bread formulated with brown rice to 38.3 mg/kg crust in the white-rice-flour-formulated bread. Methylglyoxal formation was highest in white and brown rice and lowest in wild rice and purple corn. It was observed that some phenolic compounds, such as sinapic acid, syringe acid, and malvidin, correlated negatively with MGO formation. The concentration of CML ranged from 228.23 mg/kg crust in the yellow-corn-flour-formulated bread to 626.34 mg/kg crust in the wild-rice-flour-formulated bread (Table 2). Positive correlations between the level of CML and individual phenolic compounds, such as sinapic acid, syringe acid, and malvidin, were found. However, it was observed that the phenolic compounds present in gluten-free (GF) bread formulated with the different flours were effective against the formation of Amadori products in the early MR stage and of the fluorescent compounds in the advanced stage but were not effective against the inhibition of CML formation. [PERSON] et al. investigated the formation of some MRPs (i.e., furosine, fluorescent intermediate compounds, and CML) in GF bread formulated with roasted and raw buckwheat flour [24]. It was observed that the levels of furosine were significantly reduced (about 91%) in roasted-buckwheat bread compared with raw-buckwheat bread. Negative correlations were found between the furosine content and the concentrations of p-coumaric, gallic, ferulic, vanillic, and syringe acids, and catechin and rutin, indicating that these phenolic compounds might be involved in the protein protection [29]. The concentration of fluorescent intermediate compounds were also increased by about 38% in the crust of roasted-buckwheat bread, while the level of CML level increased by about 21% in roasted-buckwheat crust [29]. There is also evidence of MRP inhibition in bread enriched with phenolic compounds obtained from tea. For instance, (\(-\))-epigallocatechin gallate (EGCG) was extracted from green tea, and the obtained powder was used in white-bread formulations at different concentrations: 3.3, 6.6, and 9.9 g\(\cdot\)kg\({}^{-1}\)[31]. Quantitation of the acrylamide content showed that the level was reduced by 30.2, 34.3, and 37.4%, respectively, compared with the control [31]. A non-linear relationship between the concentration of EGCG fortification and the acrylamide reduction in the crust of the bread was observed. EGCG may have acted as an antioxidant during baking by scavenging the free radicals; however, more studies are required to understand the chemical pathways and inhibition mechanisms. The potential of green-tea extract to inhibit acrylamide formation in rye bread has also been tested [27]. The effect of the phenolic extract addition (0.1% and 0.5% on a flour basis) was investigated in combination with other factors, such as the dough preparation method (direct and indirect) and baking temperature (230 and 260 \({}^{\circ}\)C). The addition of the green-tea extract did not affect the acrylamide content in bread prepared from sourdough, which was higher in this type of bread than in the others. It is likely that the extract had a negative effect on starter cultures by reducing free asparginase or had a synergistic action with other compounds involved in acrylamide formation [27]. The antiglycooxidative properties of the polyphenol-enriched fraction (PEF) from decaffeinated-tea dust powder have also been explored [32].