Gut microbiota metabolism of functional carbohydrates and phenolic compounds from soaked and germinated purple rice

Abstract

This study revealed that soaking and germination significantly reduced (P < 0.05) the glycemic index of purple rice (72.64 ± 0.75–61.52 ± 3.11%) and lowest value was observed with 24 h soaked sample. Non-digestible starch and phenolic metabolites in soaked purple rice could be correlated with the increased amount of Bifidobacterium (log 9.62–10.21), Lactobacillus (log 8.55–9.30) and significant decrease (P < 0.05) in growth of Clostridium/Enterobacter and Bacteroides groups during fecal fermentation. Furthermore, highest concentrations of acetate (35.27 ± 0.09 mM) and prebiotic index (PI) score of 0.79 was recorded with the soaked sample after 48 h. Phenolic metabolites including pyrocatechol, 3-(4-hydroxyphenyl) propionic acid, salicylic acid, trans-cinnamic acid and non-digestible carbohydrates metabolites were identified by LC-MS. Therefore, the soaked purple rice could be a potential functional hypoglycemic ingredient for management of gut health, diabetes, obesity and gut-brain diseases such as memory improvement in elderly.

Keywords

• Phenolics
• Functional carbohydrates
• Glycemic index
• Gut microbiota
• Purple rice