Rice is the most important staple in many Asian countries, though lately its consumption is growing in other parts of the world also. Though rice cultivation is water intensive and it may make some sense to wean away consumers from eating rice, such a strategy is unlikely to succeed because of the difficulty involved in changing traditional food consumption habits. Not that it is impossible as demonstrated in Korea, a predominantly rice consuming countries, where wheat was made popular by the United States and in southern India where population are slowly shifting to wheat from the staple food, rice. Probably such shifts in dietary pattern can take place over a long period of promotion and through adequate incentives.
Asian giants China and India are the two major rice producers accounting for almost about 340 million tons an year. Rice is a nutritional grain though its protein content is not as high as that in wheat. But the way the paddy is processed makes the difference in terms of nutrient content. There are different colored rice varieties with different colors like purple, red and black and added to these recent development of golden rice rich in carotenoids has provided another variant. Black rice is being touted as being rich in antioxidants, comparable to that in blue berries and black berries.
Processing of paddy involves dehusking and debranning to get the white cotyledon that is commonly known as rice and it is this processing step that makes it less nutritious by removing significant part of the nutrients. It is a paradox that almost all nutrients in rice are concentrated in the husk and bran portions of the grain and ironically they are considered inedible, removed during paddy processing. Bran, constituting about 10% of the grain, is also a good source of highly nutritious fat which is now being commercially exploited. Besides bran is also a rich source of sterols, gamma-oryzanols and many phenolic compounds. Rice milling industry in some countries fortify the product with vitamin B1, B2 and iron to restore that lost during polishing operation. Magnesium is one of the minerals lost irretrievably during polishing but not restored by the processor. Same is true with fiber also. Parboiling process that enables some of the soluble nutrients present in the bran to be infused into the cotyledon, makes it more nutritious. Unfortunately consumption of parboiled rice is limited to Kerala and part of Karnataka states in India.
Normal white Rice can hardly be considered as a source of antioxidants but if recent research findings are confirmed, it can be cultivated for obtaining a nutraceutical product over riding its food value. It has been found that the total phenolics and total flavonoids in immature rice grains could be significantly higher than those in mature seeds. More interestingly the bio-availability of these antioxidants is very high as most of them are in free and soluble form like Ferulic acid, ready to be absorbed by the body. The tocols which are hydrophobic antioxidants are plentiful in developing rice grain and are mainly composed of alpha-tocopherol, gamma-tocotrienol and alpha-tocotrienol. In addition, content of soluble dietary fiber in immature rice grains is found to be high that has benefits for gastrointestinal health. Based on the concentrations of bioactive compounds at different stages of rice grain development, immature grains between the 15th and 18th day after anthesis (full flowering) are suitable for nutraceutical applications.
The implications of the above findings are far reaching because here is an instance of a staple food being considered as a potential candidate for the nutraceutical industry. If rice is going to be harvested so early for use as a nutraceutical product, yield will be considerably less and consequently the cost can be very high. Rice farmers can have the choice of earmarking a part of their field for producing immature grains which can fetch them much higher returns. Before building castle in the air, concerted efforts are necessary to dwell deeper into these findings, confirm them, standardize the optimum conditions for getting maximum antioxidant content in the grain and develop delivery system for the market.