Phytochemical Characterization and Evaluation of Antioxidant Activity in Differently Polished Proso Millet

Abstract

Proso millet (PM) was polished to different degrees (4, 7, and 10%), and its nutraceutical components and antioxidant activities are characterized. PM has phenolic acids, flavonoids, carotenoids, vitamin-E, and phytosterols. Of the phenolics and flavonoids, chlorogenic acid and epicatechin were found to be highest. Among carotenoids, lutein was found to be the major component. Characterization of phytosterols showed the presence of stigmasterol, β-sitosterol, and campesterol. Stigmasterol was found to be highest in unpolished millet, and β-sitosterol was found to be highest in polished millet. Among vitamin E forms, namely, tocopherols and tocotrienols, γ-tocopherol was found to be highest. Unpolished PM showed promising antioxidant activities through DPPH, ABTS, ferric reducing antioxidant power, and radical scavenging activities. With increased degree of polishing, there was a decrease of 20–60%, 10–30%, 40–80%, and 40–60% in the contents of phenolics, carotenoids, phytosterols, and vitamin E forms, respectively, and 40–70% reduction in antioxidant activities. The higher degree of polishing significantly affected the nutraceuticals and antioxidant activities. However, after 4% polishing, the nutraceuticals offered better health benefits.