Introduction to black rice

Introduction

Black rice is a type of rice species, Oryza sativa L., which is glutinous, packed with a high level of nutrients, and mainly cultivated in Asia. The pericarp (outer part) of the kernel of this rice colour is black due to a pigment known as anthocyanin, an antioxidant. Black rice is also known as purple rice, forbidden rice, heaven rice, imperial rice, king’s rice, and prized rice. Many people assume this rice as a panacea for many culinary diseases because of its high nutritional value and curative effect. This rice is supposed to enhance longevity of life, hence it is also known as long-life rice. This rice includes several varieties with a long history of cultivation in Southeast Asian countries such as China, India, and Thailand (Kong 2008). There are more than two hundred types of black rice varieties in the world. Only China is responsible for 62% of the global production of black rice, and it has developed more than 54 modern black rice varieties with high-yielding characteristics and multiple resistances. China cultivates the most black rice, followed by Sri Lanka, Indonesia, India, and the Philippines etc. Thailand occupies the ninth position in black rice cultivation (Ichikawa et al. 2001). Interest in black rice is indicated by the number of accessions held in germplasm collections, e.g., China–359, Sri Lanka–50, Indonesia–42, India–30, the Philippines–25, and Bangladesh–24 (Chaudhary 2003). Nutrients such as protein, minerals (Ca, P, Fe, and Zn), and dietary fiber contents are higher in black rice compared to brown and white rice. Demand for this rice is growing fast in the USA and European countries due to its value as a healthy food and its attractive organic food color. Ichikawa et al. (2001) reported that black rice is efficient and two-fold stronger with respect to the antioxidant activities of blueberries. Black rice is surely a special breed of rice that is cultivated on earth. This rice is getting popular in recent years because of its high nutritional value and antioxidative properties.

Black rice is actually heirloom rice, which means it is open-pollinated, was grown at earlier times in history, and is not grown on a large scale in modern agriculture. The term ‘black rice’ actually refers to a variety of rice types from the species Oryza sativa, and is descriptive of the colour of the grain, rather than other properties. Black rice also comes in a number of short-grain, long-grain, and glutinous varieties similar to brown rice. This rice has an incredibly rich history, and among its strains is one variety known as “Imperial Rice.” Imperial rice was reserved for the emperor’s consumption only. Black rice, as one would imagine, is deep black in color and mutates into a regal purple hue when cooked. The purple colour is due to the grain’s naturally high anthocyanin content, a trait most typically observed in fruits such as blueberries and blackberries. Black rice has dark purple hues in its outer bran layer that are so intense that the rice appears to be black. Once cooked, the color lightens into that same deep purple/violet found in blueberries. This dark purple color predominantly comes from anthocyanins, which are flavonoids that perform as antioxidants in the body.

There exists no other rice with a higher nutritional spectrum than black rice. This rice is free of gluten, free of cholesterol, low in sugar, salt, and fat. Black rice is a whole grain, super-nutritious type of rice that is high in fiber, anthocyanin, antioxidants, vitamins B and E, iron, thiamine, magnesium, niacin, and phosphorus. A huge number of scientific studies show that black rice powder is one of nature's most well-balanced superfoods, and its abilities are truly remarkable. Black rice anthocyanins (BRACs) are a kind of anthocyanins that are extracted from the aleurone layer of black rice, which is a major cereal crop that has existed since ancient times in China and other Eastern Asia countries (Ling et al. 2002). The anthocyanin components in BRACs are about 26.3%, and cyanidin-3-O-glucoside and peonidin-3-O-glucoside are the main effective constituents, accounting for about 90% (Chang et al. 2010).  Among different compounds of black rice, anthocyanin is the one that mop up harmful molecules and help to protect arteries and prevent DNA damage. Anthocyanins are the flavonoid pigments of black rice and are the source of antioxidants that can inhibit the formation or reduce the concentrations of reactive cell-damaging free radicals (Adom et al. 2002). Black rice extracts could scavenge superoxide anions more effectively than hydroxyl radicals (Nam et al. 2006). This rice has long been consumed in Korea, Japan, and China (Han et al. 2004). Black rice has been eaten throughout Asia for thousands of years and has a significant history of use in China, India, and Thailand. Up until modern times, black rice was not easy to come by. It had been highly treasured and protected in Asia for many centuries. But black rice consumption is more common nowadays. This rice is becoming popular among rice consumers and dieticians day by day, mainly because of its high nutritional and medicinal value. Therefore, black rice is becoming the new “IT” organic food that everyone is talking about, and the attention it is getting is well deserved.

Dictionary meaning of black rice. (Segen's Medical Dictionary 2012)

“A strain of rice that has currency as both a food and medicine. It owes its dark colour to the high concentration of anthocyanins, which are potent antioxidants. It is regarded as a ‘superfood’ that may lower the risk of cancer due to its high concentrations of fibre, B vitamins, niacin, vitamin E, calcium, magnesium, iron, and zinc.”

Black rice includes many more varieties of dark colour rice, like Forbidden rice, Purple rice, Japonica black rice, Chinese black rice, Indonesian black rice, and Thai black rice. The reason they are grouped under the term "Black Rice" is the unusual dark/black colour of the grain. Black rice has diversity in terms of colour due to anthocyanin content and other morphological characters. Looking at black rice in the morning is an indication that the whole day will be successful. Based on historical records, black rice was only for the kings of China and Indonesia (forbidden rice). This is because black rice has a double function, namely as a source of staple food with good taste, fluffier and fragrance, as well as an efficacious medicine to cure various illnesses (Kristamtini 2009). Black rice is the most popular staple food in Europe, even more than in Southeast Asia (Simmons and Williams 1997). This rice is not currently grown on a commercial scale in the US, Europe, or other parts of the world, but it is hoped that its commercial cultivation will cover the world. Black rice is still a niche rice product, but its popularity seems to be growing.

Black rice's special and medicinal values are truly stunning even today, with all of our medical knowledge and tools. Thus, black rice is a kind of food that can make us healthy and save our lives. Black rice is a whole grain, and nowadays, whole grain is categorized as one of the potent functional food sources since they contain high amounts of phenolic compounds, especially anthocyanins in pericarp (Yawadio et al. 2007). Black rice has long been consumed in Japan and China and is considered to be a healthy food because of its antioxidant content, that are able to prevent oxidative stress. Oxidative modification of low-density lipoprotein (LDL) may play an important role in the development of atherosclerosis. Chinese black rice is rich in iron and is considered a blood tonic. This rice is claimed to be good for the kidneys, stomach, and liver in China. Previous studies show that black rice was an alternative healthy food for disease treatment as it contains antioxidative agents, such as anthocyanin (Chutipaijit et al. 2011). This rice also contains higher levels of proteins, vitamins, and minerals than common white rice (Suzuki et al. 2004). Compared to white rice, black rice is relatively rich in mineral contents such as Fe, Zn, Mn, and P, and has higher variability in mineral content that depends upon varieties and soil types of the planting area (Zhang 2000). Black rice has high nutritional value, and it contains the highest levels of anthocyanin. Its dark purple color is primarily due to its anthocyanin content, which is higher by weight than that of other coloured grains. Anthocyanins are a group of reddish-purple water-soluble flavonoids (Shen et al. 2009) located on the pericarp, seed coat, and aleurone layer (Sompong et al. 2011). Black glutinous rice has also been shown to accumulate compounds such as anthocyanins (Zhang et al. 2004) and gamma oryzanol (Juliano 2005).

 Health Benefits 

The American Heart Association, the American Cancer Society, and the 2005 Dietary Guidelines for Americans recommended an increase in the consumption of black rice to prevent heart disease and certain kinds of cancers (USA Rice Federation 2008). Moreover, the US Food and Drug Administration has recognized black rice as a healthy whole grain capable of reducing the risk of certain diseases. Unfortunately, it is not well accepted by many since it is difficult to cook and because of its distinct off taste, dark appearance, and hard-cooked rice texture. Sprouted brown, red, and black rice contains anthocyanins, antioxidants found in blueberries, grapes, and acai that have been linked to a decreased risk of heart disease and cancer (USA Rice Federation). Research suggests that plant antioxidants, which mop up harmful molecules, can help to protect arteries and prevent the DNA damage that leads to cancer (www.independent.co.uk).

Black rice contains many vitamins and minerals, including iron, vitamin A, and vitamin B, which are beneficial for overall health and the prevention of heart disease (Chen et al. 2003). The health benefits of black glutinous rice have recently been reported by several investigators. A recent report showed that anthocyanin supplementation in humans improves LDL and HDL levels (Qin 2009) and can delay cancer development in rodent models of carcinogenesis (Thomasset 2009). Black rice may have antiatherogenic activity and may improve certain metabolic pathways associated with diets high in fructose (Guo 2007). These marked health benefits have been attributed to the antioxidant properties of anthocyanins. Reactive free radicals contribute to the development of chronic inflammatory proliferative diseases (CIPDs), particularly arteriosclerosis and cancer, by causing oxidative damage to essential enzymes, cells, and tissues. Especially, very high anthocyanin content with superior antioxidant properties in sticky black rice helps to prevent the harmful effects of free radicals. The anthocyanins in rice act as antioxidants which can inhibit inflammation throughout the body (Tsuda et al. 1996), act as anticancer agents (Chen et al. 2006), promote blood circulation, slow damage and aging of tissues, reduce cholesterol and blood sugar levels, affect pituitary gland function, inhibit gastric acid secretion and inhibit platelet aggregation (Butelli et al. 2005). Defa (2006) showed the presence of nutrients, especially in sticky black rice as fiber, protein, essential amino acids, B vitamins, minerals, etc., which stand out from the others and are completely beneficial to human health. The use of food products from rice gives up germs that help to prevent headaches, relieve symptoms of constipation, prevent colon cancer, adjust blood sugar levels, prevent heart disease, lower blood pressure, and prevent Alzheimer's disease (Kayahara and Tsukahara  2000). Young (2007) also found that the antioxidant activity of the extract from rice germ is 1.3-1.6 times higher than that of regular white rice. It is advised that rice germs have the ability to improve mental health and immunity in women who are breastfeeding (Shigeko et al. 2007). A study was conducted in China on the nutritional composition of sticky rice as "A study on special nutrient of purple glutinous rice", and Defa found that the presence of nutrients especially in sticky rice as fiber, protein, B vitamins, minerals (Ca, P, Fe, etc.) are much higher than ordinary rice and completely beneficial to human health (Defa 2006). Several studies have shown that black rice compounds can reduce low-density lipoprotein cholesterol (LDL), improve lipid profiles, have anti-inflammatory and antioxidative activities, and may help to fight heart disease and prevent diabetes (Guo et al. 2007).

Free radicals are unstable and highly reactive molecules. It is normal for bodies to produce these free radicals in small amounts. However, many factors, like metabolic stress and UV radiation, can increase the formation of these free radicals. Free radicals cause oxidative damage within the body, which may eventually result in DNA and protein damage and even cell death. Antioxidants can neutralise these free radicals and can help to prevent oxidative damage. Studies show that antioxidant supplementation can exert a preventative effect against the development of serious conditions like cancer and may improve overall health. Antioxidant supplementation has been shown to lower markers of inflammation in the body. Inflammation has been a subject of significant research interest in recent times because it is heavily involved in the pathology of serious conditions, including diabetes and cardiovascular disease. Aside from anthocyanins, black rice is rich in tocopherols, another type of powerful antioxidant which is better known collectively as vitamin E. Recent research has shown that antioxidants may work synergistically, meaning that foods containing two or more types of antioxidants may deliver greater health benefits than the sum of each antioxidant alone. Bodybuilders work very hard and place a lot of stress on their bodies. Unfortunately, strenuous exercise is known to generate a lot of free radicals. The antioxidants in black rice may assist in neutralising these damaging oxygen species. This not only has general preventative health benefits, but the high antioxidant levels also have the potential to improve post-training recovery through their role in reducing inflammation. Additionally, B vitamins, iron, and potassium are essential to muscle building. Additionally, 2-(3,4-dihydroxyphenyl)-4,6-dihydroxybenzofuran-3-carboxylic acid methyl ester and 4-carbomethoxy-6-hydroxy-2-quinolone in black rice display antioxidative activity in a 1,1-diphenyl-2-picrylhydrazyl free-radical scavenging assay (Chung and Woo 2001).

 Black rice is one of the healthiest food types of today. It is packed with a wide array of nutrients. Aside from being an extremely rich source of nutrients, black rice is comparatively cheaper and lower in sugar than other superfoods like berries. 21st-century food scientists have discovered that black rice has many health benefits. Knowing its health benefits, black rice was first introduced to the United States in 1995. Black rice (Oryza sativa L. var. japonica) has been used in folk medicine in Asia (Sim et al. 2007). Black rice varieties have also historically been used in Chinese medicine. This rice is high in nutritional value and contains 18 amino acids, iron, zinc, copper, carotene, and several important vitamins (Kushwaha 2016). Thus, black rice is a panacea.

 History of Black Rice

The origin of black rice is not well understood, but it is said that black rice might be originated from many Asian countries, including China (Hoahua et al. 1996), India (Sastry 1978), Japan (Natsumi and Noriko 1994), and Vietnam (Quan 1999). Black rice was known long before Chinese dynastic times. During the Warring States Period (476 - 221 BCE), a different tale of its use was told. One General Sun Bin was caged; the reasons were unclear, and he survived because he ate black rice balls. In Hangzhou, where this General came from, they honor him by eating black rice on the first day of the Chinese summer (www.flavorandfortune.com).

Black Rice is commonly known as “forbidden rice”. The name forbidden rice implies that consuming this rice without approval from the proper authorities can have life-threatening consequences for those involved. In ancient China, black rice was set specifically for the Emperor or the royal family. Common people were not allowed anywhere near the stuff. Really incredible fact about black rice is that it contains even more antioxidants (per serving) than blueberries, which are famous for their anti-aging properties.

 

The Emperor says, “Hands off the black rice! It’s mine.”

 

According to ancient Chinese legend, black rice was so rare, tasty, and nutritious that only the emperors were allowed to eat it. Times have changed, and are now available everywhere. Although black rice is still relatively rare, researchers are trying to bring its distinctive flavor and mixture of antioxidants to the masses (www.cnn.com). Emperors reserved this wonderfully nutty rice for their own consumption because it was thought that it would extend their lives. It is highly likely that the emperors down throughout the ages probably shared their black rice stock with their consorts or concubines.

 

Black Rice History in Nepal

Black rice is a highly costly rice. It is said that the black rice entered more than 15 years ago by public domains in Nepal either from China, India, Korea, or Japan. However, real research started when Nepalese scientist Dr. UKS Kushwaha started black rice (coarse grain type) yield testing in an observation yield trial at Khumaltar under the Agriculture Botany Division (ABD) in 2013/14. Fine black rice was introduced in Nepal in 2015 by UKS Kushwaha (seeds were provided to him from Rajendra Bhattarai of the Agronomy Division, Khumaltar). Dr Kushwaha conducted further research trials in 2016 in the National Plant Breeding and Genetics Research Centre, Khumaltar, Lalitpur, farm. Kushwaha distributed more than 100 pockets of black rice to different parts of Nepal to interested farmers. Now this rice is widely grown in different parts of Nepal (Kushwaha 2016). Thus, Dr. Kushwaha is a pioneering man of black rice in Nepal.

 Book: Black Rice Research History and Development

Keywords: black rice, purple rice, brown rice, polished rice, rice, paddy, crop, grain

 References:

Adom KK, Liu RH (2002) Antioxidant activity of grains. Journal of Agricultural and Food Chemistry 50:6170–6182

Butelli E, Titta L, Giorgio M, Mock H, Matros A, Peterek S (2008) Enrichment of tomato fruit with health-promoting anthocyanins by expression of select transcription factors. Nat Biotechnol 26:1301–1308

Chang KK, Kikuchi S, Kim YK, Park SH, Yoon U, Lee GS, Choi JW, Kim YH, Park SC (2010) Computational identification of seed specific transcription factors involved in anthocyanin production in black rice Biochip J 4(3); 247-255

Chaudhary RC (2003) Speciality rices of the world: Effect of WTO and IPR on its production trend and marketing. Journal of Food, Agriculture and Environment 1(2):34–41

Chen CC, Hsu JD, Wang SF, Chiang HC, Yang MY, Kao ES (2003) Hibiscus sabdariffa extract inhibits the development of atherosclerosis in cholesterol fed rabbits. J Agric Food Chem 51:5472–5477

Chen PN, Kuo WH, Chiang CL, Chiou HL, Hsieh YS, Chu SC (2006) Black rice anthocyanins inhibit cancer cells invasion via repressions of MMPs and u-PA expression, Chemico-Biological Interactions 163:218–229

Chung HS, Woo WS (2001) A quinolone alkaloid with antioxidant activity from the aleurone layer of anthocyanin-pigmented rice. J Nat Prod 64:1579-1580

Chutipaijit S, Chaum S, Sompornpailin K (2011) High contents of proline and anthocyanin increase protective response to salinity in Oryza sativa L. spp. Indica, AJCS 5(10):1191-1198

Defa G, Meizu XA (2006) Study on special nutrient of purple glutinous rice, Shanghai acdemy of agricultural science, Shanghai

Defa G, Meizu XA (2006) Study on special nutrient of purple glutinous rice, Shanghai acdemy of agricultural science, Shanghai

Guo H, Ling W, Wang Q, Liu C, Hu Y, Xia M, Feng X, Xia X (2007) Effect of anthocyanin rich extract from black rice (Oryza sativa L. indica) on hyperlipidemia and insulin resistance in fructose-fed rats. Plant Foods for Human Nutrition 62:1-6

Guo H, Ling W, Wang Q, Liu C, Hu Y, Xia M, Feng X, Xia X (2007) Effect of anthocyanin rich extract from black rice (Oryza sativa L. indica) on hyperlipidemia and insulin resistance in fructose-fed rats. Plant Foods for Human Nutrition 62:1-6

Han SJ, Ryu SN, Kang SS (2004) A new 2-arylbenzofuran with antioxidant activity from the black colored rice (Oryza sativa L.) bran. Chem Pharm Bull 52:1365-1366

Hoahua HE, Pan X, Zao Z, Liu Y (1996) Properties of the pigment in black rice. Chinese Rice Res News 4(2):11-12

Ichikawa H, Ichiyanagi T, Xu B, Yoshii Y, Nakajima M, Konishi T (2001) Antioxidant activity of anthocyanin extract from purple black rice. Journal of Medicinal Food 4(4):211–218

Juliano C, Cossu M, Alamanni MC, Piu L (2005) Antioxidant activity of gamma-oryzanol: Mechanism of action and its effect on oxidative stability of pharmaceutical oils. Int J Pharm 299:146–54

Kayahara H, Tukahara K (2000) Flavor, health, and nutritional quality of pre-germinated brown rice. In: International Conference at International Chemical Congress Pacific Basin Society; 2000 December, Hawaii

Kong L, Wang Y, Cao Y (2008) Determination of Myo-inositol and D-chiro-inositol in black rice bran by capillary electrophoresiswith electrochemical detection. J Food Compos

Kristamtini (2009) Mengenal beras hitam dari bantul. Tabloid Sinar Tani. 13 Mei

Kushwaha UKS (2016). Black Rice-Research, History and Development (book). Springer International Publishing

Ling WH, Wang LL, Ma J (2002) Supplementation of theblack rice outer layer fraction to rabbits decreasesatherosclerotic plaque formation and increases antioxidantstatus. Journal of Nutrition 132:20–26

Natsumi T, Noriko O (1994) Physicochemical properties of kurogome, a Japanese native black rice. Part 1 Bull. Gifu Women’s Coll 23:105-113

Quan LH (1999) Selection of yeast for beverage production from black rice. Nong Nghiep Cong Nghiep Thue Pham 8:375-376

Sastry SVS (1978) Inheritance of genes controlling glume size, pericarp colour, and their interrelationships in indica rice. Oryza 15:177-179

Shen Y, Jin L, Xiao P, Yan L, Jinsong B (2009) Total phenolics, flavonoids, antioxidant capacity in rice grain and their relation to grain color size and weight. Journal of Cereal science 49(1): 106-111

Shigeko S, Takashi H, Keiko H, Fumie M, Miyo H, Koichi K et al. (2007) Pregerminated brown rice could enhance maternal mental health and immunity during lactation. Eur J Nutr 46:391-396

Sim GS, Lee DH, Kim JH, An SK, Choe TB, Kwon TJ, Pyo HB, Lee BC (2007) Black rice (Oryza sativa L. var. japonica) hydrolyzed peptides induce expression of hyaluronan synthase 2 gene in HaCaT keratinocytes. Journal of microbiology and biotechnology 17(2):271-279

Simmons D, R Williams (1997) Dietary practices among Europeans and different South Asian groups in conventry. Br J Nutr 78:5-14

Sompong R, Siebenhandl ES, Linsberger MG, Berghofer E (2011) Physicochemical and antioxidative properties of red and black rice varieties from Thailand, China and Sri Lanka. Food Chemistry 124(1):132-140

Suzuki M, Kimur T, Yamagishi K, Shinmoto H, Yamak K (2004) Comparison of Mineral Contents in 8 Cultivars of Pigmented Brown rice. Nippon Shokuhin Kagaku Kogaku Kaishi. 51(58):424-427

Tsuda T, Shiga K, Ohshima K, Kawakishi S, Osawa T (1996) Inhibition of lipid peroxidation and the active oxygen radical scavenging effect of anthocyanin pigments isolated from Phaseolus vulgaris L. Biochem Pharmacol 52:1033–1039

Yawadio R, Tanimori S, Morita N (2007) Identification of phenolic compounds isolated from pigmented rices and their aldose reductase inhibitory activities. Food Chemistry 101:1616–1625

Young S, Kim SJ (2007) Isolation of anthocyanin from black rice (Heugjinjubyeo) and screening of its antioxidant activities. Department of Biotechnology, School of Life Sciences and Biotechnology, Korea University, p 136-701

Zhang MW (2000) Specialty Rice and its Processing Techniques. China Light Industry Press, Beijing. p 47-83

Zhang MW, Guo BJ, Peng ZM (2004) Genetic effects on Fe, Zn, Mn and P contents in Indica black pericarp rice and their genetic correlations with grain characteristics. Euphytica 135:315–323