Effect of different processing technologies on phenolic acids, flavonoids and other antioxidants content in pigmented rice

Rice is consumed in the form of different products. The present study reported the extractable and free form of phenolic acids and flavonoid profile from different processed products (popped, beaten, puffed and boiled rice) of four black rice cultivars (Chakhao, Kalobhat, Mamihunger. Manipuri Black) along with a white rice variety (Swarna sub-1) as reference. In addition, vitamin-E, γ-oryzanol, anthocyanin, phytic acids and antioxidant activity were also examined. The HPLC-PDA analysis of phenol extracts detected 14 phenolic compounds comprising of 4 hydroxybenzoic acid, 5 hydroxycinnamic acid and 5 flavonoids in most of the products with their higher content in black rice based products than that of reference cultivar. Among the different products, popped rice ranked first in terms of mean phenolic compounds (467.74 μg/g) of which 54% occurring in free form, vitamin-E, γ-oryzanol and antioxidant activity. Boiled rice had the least amount of all these components. Based on PCA, popped rice of MN was identified as a promising product that could contribute to potential health benefits.