Interactions between ferulic and chlorogenic acids as a main factor determining antiradical activity of wholemeal wheat bread enriched with green coffee

The hydroxyl radical (·OH) is primarily responsible for the cytotoxic effects of oxygen. Hydroxyl radicals can be produced from O₂ under stress conditions and are involved in numerous disorders such as inflammations. Interactions between potentially mastication extractable (BE), potentially bioaccessible (DE) and potentially bioavailable (AE) compounds able to scavenge OH· radicals derived from green coffee and wholemeal wheat flour were studied. Green coffee (Coffea arabica) beans (GCB) and wheat bread flour (600 g), type 2000 (average 1,8 g/100 g ash content, humidity14 g/100 g) were used. Results were compared with those obtained for pure chlorogenic and ferulic acids (Sigma-Aldrich, Poland). For interactions determination the isobolographic analysis was used. BE, DE and AE phytochemicals were released during digestion in the simulated human gastrointestinal tract. For functional food preparation bread flour was replaced with GCB flour at 1 to 5% levels (GC1, GC2, GC3, GC4 and GC5, respectively). Taking into account the isobole shape it may be concluded that chlorogenic and ferulic acids acted synergistically. In the same way acted BE and AE compounds derived from tested raw materials. Only in the case of DE additive interactions were found. GCB addition significantly enriched wheat bread with antiradical compounds. The highest activity was found for extracts obtained after simulated digestion which indicates high potential bioaccessibility of active compounds. Most importantly, these phytochemicals were highly bioavailable in vitro. Due to fact that bread is one of the main products consumed in the cultural area of many countries and resignation from its consumption for many people is impossible, the proposed product is mainly targeted at this group of consumers – it is a compromise between "traditional" and pro-health food.

Acknowledgement: The study was financed by the Polish National Science Centre (grant 2013/09/B/NZ9/01801).