Identification of Nutraceuticals and Antioxidant Activity in Low-Cost Broken Rice Varieties

Abstract

Rice grains are the main crops consumed by more than half of the world’s population. White rice contains carbohydrates, while pigmented rice varieties are more nutritious, with bioactive compounds that can potentially prevent pro-inflammatory diseases like diabetes and hypertension. Broken rice is produced in large quantities as a cheap by-product of milling; however, its nutraceutical contents have not been identified. Therefore, the research aimed to examine four low-cost broken rice varieties’ color values and bioactive compound contents. Kiaw-Ngu glutinous rice (white rice) and brown Jasmine rice 105 were used as control, while Riceberry rice and Sangyod rice represented pigmented rice varieties. Color values were analyzed using the RHS color chart and the CIE L*a*b* color space system. Antioxidant activity was measured using DPPH assay, while total phenolic compounds were determined by the Folin–Ciocalteu’s method. Water-soluble vitamins (B1, 2, and 6) and fat-soluble vitamins (E and -carotene) were determined using HPLC. The analyzed results illustrated that the Riceberry rice had the most potent antioxidant activity (83.45%), followed by Sangyod rice, brown Jasmine rice 105, and Kiaw-Ngu glutinous rice, respectively. Similarly, Riceberry rice contained the highest level of total phenolic acid (236.98 mg gallic acid equivalent (GAE)/g). Vitamin B1 level is highest in the Riceberry rice, while vitamin B2 level was comparably highest in the Riceberry rice and Sangyod rice. However, vitamin B6 was not detectable in any strains of the rice varieties. The Riceberry rice and Sangyod rice also contained vitamin E and β-carotene. In conclusion, pigmented rice grains possess antioxidant activity, phenolic acids, vitamins B1, B2, E, and β-carotene.