Quinoa treated by an optimized method of microwave heating and their effect on antioxidant activity and phenolic compounds after in vitro gastrointestinal digestion

Heating by microwave irradiation could be an alternative for cooking quinoa and improving its content of phenolic compounds, which have health-promoting properties. The goal of this study was to improve the bioaccessibility of phenolics content and antioxidant activity of quinoa using an optimized method of microwave irradiation. The best microwave irradiation conditions obtained by maximizing the responses were 100% irradiation power and 14 min of irradiation time. The predicted and experimentally validated values for total phenols, flavonoids, and antioxidant activity were as follows: 686.46 vs 749.67 ± 36.62 µg GAE/g; 743.94 vs 803.37 µg QE/g and 4.20 vs 4.61 µM TE/g, respectively. At the gastric level, heating by microwave irradiation promoted the bioaccessibility (>100%) of total phenols, flavonoids, and antioxidant activity, as well as gallic and coumaric acids, quercetin, and kaempferol greater. The heating treatment by microwave in quinoa could be useful to obtain new products with bioactivity potential at gastric and intestinal levels.