The impact of simulated gastrointestinal digestion on the bioaccessibility and antioxidant activity of purple rice phenolic compounds

Polyphenol-rich purple rice has been shown to exhibit a wide range of health properties including antioxidant activity. This study aimed to determine the impact that gastrointestinal digestion of purple rice had on its phenolic bioaccessibility and antioxidant activity. Our results demonstrated a significant difference (p < 0.01) in bioaccessible phenolic content level and antioxidant activity between simulated gastric and intestinal digestion. However, mass spectrometry and ultra-high-performance liquid chromatography (UHPLC) coupled with online ABTS^•+ scavenging activity demonstrated a significant loss in the number of polyphenols that were bioaccessible after digestion. Interestingly, substantial free radical scavenging activity was retained after digestion due to the bioaccessibility of bioactive compounds such as tryptophan and protocatechuic acid. Hence, purple rice may be considered as a source of bioaccessible phenolic and antioxidant compounds.