Nutrients and antioxidant properties of Indonesian underutilized colored rice

Purpose - The paper aims to investigate the iron, zinc, carotenoid, vitamin E, anthocyanin, and phenolic contents, antioxidant activity and the effect of the boiling of rice on such parameters. Design/methodology/approach - Iron and zinc content were investigated using atomic absorption spectrometry. Meanwhile, simultaneous extraction and detection methods using high performance liquid chromatography were applied for carotenoids, tocopherol, and tocotrienol analyses. For anthocyanin and phenolic determination, pH differential method and Folin Ciocalteu method were used, respectively. Antioxidant activity of samples was examined using ferric reducing antioxidant power (FRAP) and superoxide radical scavenging methods. Findings - The n790 cultivar has a higher iron, zinc gamma tocopherol (1,869.64 mg/kg), a tocopherol (1,883.97 mg/kg), anthocyanin (205.54 mg cyanidin 3 glucoside equivalent/100 g dry matter), and phenolic (728.9 mg catechin equivalent/100 g dry matter) contents. Jowo cultivar has higher lutein (1,314.21 mg/kg), alpha carotene (823.29 mg/kg), and beta carotene (71.73 mg/kg) contents. Meanwhile, gamma tocotrienol is the most abundant tocotrienol found in all samples. N790 cultivar had the highest antioxidative potential in FRAP, and superoxide radical methods. Boiling did not significantly affect the zinc content, however, different response was found in carotenoid, tocopherol, and tocotrienol content. Moreover, boiling decreased the antioxidant activity of extract. Practical implications - Black- and red- colored rice could substitute white rice in Indonesian diet to achieve better nutrient intake. Originality/value - Providing information on nutrient and bioactive compound of Indonesian underutilized colored rice can help to change the dietary habit and to alleviate nutrient deficiency in Indonesia.