Effects of Roasting and Extrusion Puffing on the Antihypertensive Activity of Blended Grains in Spontaneously Hypertensive Rats

We investigated the effects of processing (roasting and extrusion puffing) on the antihypertensive activity of blended grains both in vitro and in vivo. The blended grains were composed of sorghum (Sorghum bicolor), adzuki bean (Vigna angularis), and finger millet (Eleusine coracana). In the in vitro studies, total phenolic content (TPC), total flavonoid content (TFC), and angiotensin-converting enzyme (ACE) inhibitory activity of blended grains were evaluated. The results showed a significant decreasing trend in TPC, TFC, and ACE inhibitory activity in the following order: nonprocessed blended grains (NPBG) > roasted blended grains (RBG) > extrusion puffed blended grains (EPBG). Spontaneously hypertensive rats (SHRs) were fed a diet containing 40% blended grains (replacing the standard diet) for 8 weeks. None of the blended grains had any effects on feed intake, liver function, and serum lipid profile. Notably, NPBG showed the greatest reduction in systolic blood pressure compared to the model control (MC), followed by RBG, and EPBG, whereas diastolic blood pressure was significantly decreased in NPBG and RBG. Serum ACE activity and angiotensin II levels significantly decreased in all blended grains, with NPBG and RBG showing the most significant decrease in angiotensin II levels. Moreover, the mRNA expression of renin, a hormone involved in hypertension, was significantly decreased in NPBG and RBG. Only NPBG ameliorated aortic vascular remodeling compared to the MC. These results suggest that NPBG exhibited the most potent antihypertensive activity; however, roasting could be an effective processing method for maintaining antihypertensive effects compared to extrusion puffing.