Non-volatile compounds and blood pressure-lowering activity of Inpari 30 and Cempo Ireng fermented and non-fermented rice bran

Rice bran, a by-product of the rice milling process, has high nutritional and bioactive components. The fermentation process has been adopted to enhance the nutritional quality of rice bran. The objective of this study was to identify and compare non-volatile compounds of fermented and non-fermented Inpari 30 and Cempo Ireng rice bran and its blood pressure-lowering activity. Each sample of rice bran was fermented by Rhizopous oligosporus for 72 hours at 30 °C, using solid-state fermentation. In this study, non-fermented rice bran was used as a control. Non-targeted analysis of samples was carried out by Ultra performance liquid chromatography-tandem mass spectrometry with electrospray ionization in positive ion mode. For animal study, we used stroke-prone spontaneously hypertensive rats (SHRSP)-a model of hypertension-related disorders similar to human essential hypertension. Principal component analysis was done to categorize non-volatile compounds, based on its relative concentration. Seventy-two non-volatile compounds were identified in fermented and non-fermented rice bran, classified into secondary metabolites (36 compounds), lipids (16 compounds), amino acids (8 compounds), vitamins and cofactors (7 compounds), peptides (3 compounds), nucleotides (1 compound), and carbohydrates (1 compound). Adenosine was the most dominant of the non-volatile compounds in all rice bran samples. Further, blood pressure-lowering activity was shown in Inpari 30 fermented rice bran after six hours of administration in SHRSP. This study revealed a diversity of non-volatile compounds in fermented and non-fermented versions of Inpari 30 and Cempo Ireng rice bran that have anti-hypertensive effects. This study may provide opportunities to promote the production of fermented RB as a functional ingredient with enhanced bioactivity.