Vol.10 (2020) No. 4 ISSN: 2088-5334 Physical Properties and Glycemic Index of Organic and Conventional Black Rice Grown in Bali, Indonesia Anak Agung Sagung Putri Risa Andriani a , Mohamad Hasnul Naim Abd Hamid b , Mohamad Sazuan Sahrom b , Mohd Syukri M Yusof c and Bohari M Yamin d a Program Studi Agroteknologi, Fakultas Pertanian, Universitas Warmadewa. Denpasar, Indonesia E-mail: putri_risa69@yahoo.com b Research and Instrumentation Center, Universiti Kebangsaan Malaysia, Bangi, 43600 Selangor. Malaysia c Faculty of Science and Technology, Universiti Malaysia Terengganu, Kuala Terengganu 21030. Malaysia d School of Chemistry, Universiti Kebangsaan Malaysia, Bangi, 43600 Selangor. Malaysia Abstract— Similar variety of black rice was grown by organic and conventional methods in Jatiluweh and Penatih districts of West Bali, respectively, separated by 46 km distance. Each rice is very similar, having black pericarp and white rice inside. In this study, we found that the degree of crystallinity of the two rice is about 24%. The Bragg parameters of the conventional rice are very close to dehydrating α-amylose, whereas the organic rice exists in polymorphic form. The crystallites in the endosperm area are dominated by polyhedral shapes in contact with each other at the edges and formed a cyclic geometric environment. The size of the crystallites was between three and six microns. Overall, the crystallites are packed in rectangular blocks connected radially from the center towards the pericarp. XRF experiments show each rice contain P, K, S, Si, Mg, Cl, Al, Zn, Fe, Cu, and Rb. However, ruthenium and manganese were detected in organic rice. Both organic and conventional black rice possesses a low glycemic index of about 31±5.0 compared to 50±5.8 for commercial Basmati rice. Thermogravimetric investigation showed that the black rice was stable up to about 300°C, and the gradual mass loss between 80 and 210°C is due to water molecules and additional components present in the rice. After the major decomposition at 310°C, the mass gradually decreased and reached 18% residual at 600°C. Keywords— black organic Bali rice; crystallinity; polymorphism; glycemic index percentage; endosperm and thermogram. I. INTRODUCTION Colored rice is beginning to receive acceptance due to its health properties despite its slight differences in taste, physical, and chemical properties compared to the normal white rice. High carbohydrate rice has become the subject of concern due to the increase in diabetes as a significant chronic disease in many countries, including Japan, where type-2 diabetic has been associated with the traditional dietary pattern of Japanese white rice as staple food [1]–[4]. The presence of anthocyanin in the colored rice played an important role not only to the physical and chemical properties of the rice but also to the health-promoting aspect as it is known as a good antioxidant. Besides, there are polyphenols, flavonoids, and vitamins also present [5], [6]. Black rice was reported to contain the highest total anthocyanin of 327.60mg per 100 g compared to other colored rice varieties [7]. Anthocyanin extract of black rice has been shown to inhibit cancer cell proliferation in vitro [8] and reduced significantly improves lipid profile and inflammatory status [9]. It also provides endless opportunities for diversification of rice-based food products in the beverage industries. Today, we can find some colored rice in 1 to 5 kg of packaging are being sold in the hypermarket and mostly came from Thailand, China, Sri Langka, India, and Indonesia. In Indonesia, there are more than 50 accession numbers for germplasm collections [10]. However, there are only 24 names of local colored cultivars [11]–[14] being grown mainly in Java and Sulawesi. Recently colored rice is also grown in Sumatra. One thing for sure is that all the rice is given a name based on the location or name of the farmers (accession number) and that it needs further analysis of their genotypes. Black and brown rice are also cultivated in Bali and sold for local consumption. No detailed information or specification is given unless it is sold in proper packaging as in the hypermarket. Therefore, we decided to carry out the detailed physical and chemical studies on our local black rice 1688