American consumers have the luxury of choosing from a variety of rice that spans from white and brown to Jasmine and Basmati. Soon to be added to that selection will be an even more nutritious variety of rice that has been known to Asian consumers for centuries. Black rice, currently found primarily in specialty food markets, will likely be making its way out into larger consumer markets soon thanks to research presented at a recent meeting of the American Chemical Society (ACS). Black rice, they said, has a high antioxidant content—a distinction that makes it stand apart from other varieties of rice.
Black rice has an incredibly rich history and counts among its strains one variety known as “Imperial Rice” because it was reserved for the Emperor’s consumption only. In present day, black rice consumption is more common.
Black rice, as one would imagine, is deep black in color and mutates into a regal purple hue when cooked. The purple color is due to the grain’s naturally high anthocyanin content, a trait most typically observed in fruits such as blueberries and blackberries.
“Just a spoonful of black rice bran contains more health promoting anthocyanin antioxidants than are found in a spoonful of blueberries, but with less sugar and more fiber and vitamin E antioxidants,” said Dr. Zhimin Xu, associate professor at the Department of Food Science at Louisiana State University Agricultural Center in Baton Rouge, LA, during his presentation at the ACS meeting. “If berries are used to boost health, why not black rice and black rice bran? Especially, black rice bran would be a unique and economical material to increase consumption of health promoting antioxidants.”
Like fruits, black rice is rich in anthocyanin antioxidants, substances that show promise for fighting heart disease, cancer and other diseases. Food manufacturers could potentially use black rice bran or the bran extracts to boost the health value of breakfast cereals, beverages, cakes, cookies and other foods, Dr. Xu and his research team suggested.
In an interview with Nutraceuticals World, Dr. Xu explained that nutritional potential of black rice captured his attention a few years ago, while he and his colleagues were conducting research on fat-soluble nutraceuticals. “My lab has been working on fat-soluble nutraceuticals, such as gamma-tocotrienol and oryzanol in brown rice bran for many years. Also, my lab is doing several projects related to water-soluble anthocyanins antioxidants in berries and grapes these years,” he said. “As these sources are only rich in either fat or water-soluble antioxidants, it led me to think which one source has both types of the antioxidants, which might have synergic health function in preventing chronic diseases. So, black rice bran got my attention. The hypothesis was that the bran still presented a fat-soluble antioxidant while its black color is water-soluble anthocyanins.”
Most consumers are already aware that conventional brown rice is nutritionally superior to white rice in the way of fiber and beneficial vitamins because its outer layer (also known as a husk or chaff) and bran layers remain intact during processing. Brown rice is the most widely produced rice variety worldwide.
Dr. Xu explained that the bran of brown rice contains a higher level of gamma-tocotrienol, one of vitamin E compounds, and gamma-oryzanol antioxidants, which are lipid-soluble antioxidants. “Numerous studies showed that these antioxidants can reduce blood levels of low-density lipoprotein (LDL) cholesterol—so called ‘bad’ cholesterol—and may help fight heart disease,” he said.
Dr. Xu and colleagues analyzed samples of black rice bran from rice grown in the southern U.S. In addition, the lipid-soluble antioxidants they found in black rice bran possessed a higher level of anthocyanins antioxidants, which are water-soluble antioxidants. Thus, he concluded, black rice bran may be even healthier than brown rice bran.
“The average anthocyanins content in black rice bran is over 3.5 mg/g,” he said. “The content of vitamin E is between 0.01-0.05% and oryzanol is 0.1-0.3%. The fiber content is 7-11%.”
The team spent two years working on its black rice study prior to presenting their findings to the ACS. They are currently developing a technology to utilize black rice bran as a natural food ingredient, which, in turn, might facilitate its use in different food products. They also plan to secure the rights to the outcome of their work before publishing their research.
The scientists also demonstrated how the pigments in black rice bran extracts can produce a variety of different colors, ranging from pink to black—a phenomenon they said may help provide a healthier alternative to artificial food colorants that manufacturers now add to some foods and beverages, as several studies have linked some artificial colorants to cancer, behavioral problems in children and other health problems.
Black rice is used mainly in Asia for food decoration, noodles, sushi and pudding. Dr. Xu said that farmers are interested in growing black rice in Louisiana and that he would like to see people in the country embrace its use. “The black rice bran can be used for breakfast cereals, baked products, bars and tablets,” he commented.
In China, noodles made from black rice have recently begun to be produced and at least one U.S. bread company—CA-based Food For Life Baking Company Inc.—has also begun producing “Chinese Black Rice” bread.