In vitro Short‐Chain Fatty Acid Production of Rice Bran Components by Human Gut Microbiota

Abstract

Rice bran is a rich source of bioactive components that have potentials to promote gastrointestinal health. However, bran is typically removed during polishing. Among those, feruloylated arabinoxylan oligosaccharides (FAXO) and rice bran polyphenolics (RBPP) are believed to have positive impacts on human gut microbiota. The objective of this study is to investigate the ability of FAXO and 50% ethanol fraction of RBPP to increase short‐chain fatty acids (SCFA) production, including acetic, propionic, and butyric acid, which are strongly associated with colonic health in human. Fresh fecal samples collected from five healthy adults with no signs or symptoms of bowel diseases or conditions were diluted with anaerobic medium. Each sample received 5 treatments separately: Blank (no substrates), Control (fructooligosaccharides – FOS, prebiotic), FAXO, RBPP, and FAXO with RBPP. Samples were prepared inside an anaerobic chamber, then capped and sealed tightly. Samples were incubated at 37°C. An aliquot of 1.5 mL was drawn from each treatment test tube at 0, 4, 8, 12, 24, and 30 hours and stored immediately at −80°C. SCFA concentrations were measured quantitatively using gas chromatography. Results showed that SCFA productions were increased with the addition of FAXO. Although total SCFA production of FAXO was not significantly higher than that of FOS, individual SCFA productions of FAXO were significantly higher compared to FOS (P<0.05). Propionic acid production of FAXO was higher compared to FOS at timepoint 24‐hour (2.32±0.70 mM and 0.34±0.36 mM, respectively) and 30‐hour (2.48±0.70 mM and 0.17±0.61 mM, respectively). FAXO also produced more butyric acid compared to FOS at 12‐hour (1.98±0.24 mM and 0.36±0.76 mM, respectively), 24‐hour (2.53±0.48 mM and 0.56±0.58 mM, respectively), and 30‐hour (2.90±0.80 mM and 0.51±0.62 mM, respectively). However, the synergistic effects of FAXO and RBPP were not observed as their combination did not increase SCFA productions significantly compared to FAXO treatment. Results from this study showed that FAXO exhibited prebiotic‐like activities and can potentially be used as a functional ingredient to promote colon health.Support or Funding InformationFunding provided by the USDA NIFA (Grant No. 2014‐67017‐21766) is gratefully acknowledged.