Effect of milling on in vitro Digestion-Induced release and bioaccessibility of active compounds in rice

To investigate the impact of milling on the active components in rice, this study examined the stability of phenols, vitamin B1 (VB1), and alpha-aminobutyric acid (α-GABA) during cooking and digestion of rice and their distribution in digestive juices and residue by adjusting the degree of milling (DOM). The findings revealed that milling exacerbated the instability of γ-GABA during cooking and VB1 during digestion. Their total losses peaked at 19.76% and 39.53% as DOM respectively reached 6.07% and 8.06%. In vitro digestion combined with release mathematical models demonstrated the impact of milling on their bioaccessibility. This effect increased the small intestinal bioaccessibility of phenols and γ-GABA, whilst reducing that of VB1. This was attributed to milling-induced pre-gastric full release of VB1, which amplifies its intestinal susceptibility and induces its re-entry into digestive residues. In conclusion, this study recommends keeping DOM below 6.07% to optimize the bioaccessibility of these active compounds.