Black rice starch: physicochemical characterization and nutritional properties

Approximately 95% of rice is cultivated in Asiaout of which many are pigmented, and it is primarily consumed in Asian countries, especially in China, Indonesia, and Korea. India constitutes about 5.1% of the total world production of pigmented rice. Out of many unexplored pigmented rice, Black rice (Oryza sativa L.) of North East India is widely popular for its distinct flavor and has immense significance in the rice value chain system. Its pigment, flavor and aroma, chemical composition, and volatility are still being studied by many researchers. Black rice is found to be advantageous as compared to white rice due to its high anthocyanin, protein, vitamin, and mineral content, which varies with different cultivars. The chemical composition of rice highly depends on the amount of starch, lipids, and protein profile of the variety, which ranges from 60%–80% starch, 1%–4% lipid, and 6%–9% protein on the basis of which the functional quality of black rice also differs. The nutritional and functional quality of starch in black rice cultivars varies differently with different landraces for which efforts should be made to maintain the geographic identity, value chain, and utilization of the same. Black rice starch is found to have a better physicochemical and nutritional profile in terms of its thermal, rheological, and presence of bioactive compounds as compared to conventional starch sources such as white rice and wheat. It has more resistant starch content and the starch profile tends to have a bit longer cooking time, moderate gruel solid loss, low water uptake ratio, and swelling capacity while cooking. In this chapter, the nutritional, physicochemical characteristics, functionality, isolation, modification, and applications of black rice starch have been studied in detail with a focus on Indian black rice.