colitis [181, 190], childhood and adolescent obesity [181, 191], high levels of cholesterol [48, 181, 184, 192–196], colon cancer [181], and diabetes [181, 194, 197–200].
3.2.7 Brown Rice
Oryza sativa L., or rice, is the cereal grain cultivated most heavily on a global level [201–203], being grown in more than 100 countries [204, 205]. In rice cultivation, the ability to use soils that have different temperatures, various levels of moisture from dry conditions to marshiness, and many different textures, such as muddy or sandy, ensures that rice remains a producible cereal worldwide [206, 207]. Over 90% of all rice globally produced is grown and processed in Asia. Rice is a livelihood for 2.5 billion people [205, 208], and it constitutes the main source of sustenance for almost 50% of the global population [202, 203]. It is primarily produced for consumption by humans, which is the destiny of over 80% of all produced rice, and it is less commonly used as an animal feed [207, 209].
The production of brown rice occurs with the dehulling of rough rice. It comprises layers of 6%–7% bran layers and 2%–3% embryo, with a large majority of approximately 90% being constituted by the endosperm [202, 210]. White rice is also known as polished rice, procured by the removal of bran from brown rice. Although slight variations exist according to the degree of milling, white rice is essentially understood to be composed of only endosperm [207, 209].
The composition of brown rice has been reported by Zhou and Zhang (2002) [211] as protein (7.1–13.1 μg/g), crude fat (1.8–4.0 μg/g), crude fiber (0.2–2.6 μg/g), vitamin A (0.1 μg/g), vitamin B1 (2.1–4.5 μg/g), vitamin B2 (0.4–0.9 μg/g), vitamin B (0.005 μg/g), vitamin E (13 μg/g), nicotinic acid (44–62 μg/g), pyridoxol (1.6–11.2 μg/g), pantothenic acid (6.6–18.6 μg/g), biotin (0.06–0.13 μg/g), total inositol (1194–1220 μg/g), free inositol (24–45 μg/g), choline (1120–1220 μg/g), and folic acid (0.20–0.60 μg/g). The mineral substances of brown rice are 65–400 μg/g Ca, 203–275 μg/g Cl, 7–54 μg/g Fe, 13–42 μg/g Mn, 2500–4400 μg/g P, 1200–3400 μg/g K, 31–176 μg/g Na, and 15–22 μg/g Zn [205]. Brown rice has higher ratios of fundamental nutrients than its white counterpart. Also, it contains extra bioactive compounds like γ-oryzanol, ferulic acid, and gammaaminobutyric acid that are primarily found in the germ and in the bran layers [205, 206, 212]. In spite of its considerable nutritional value, brown rice is less likely to be consumed than white rice is on account of its rougher texture, lower digestibility, an off-putting bran odor, and longer cooking times [205–207, 213]. To overcome these negative features, the consumption of germinated brown rice can stand out [207].
Brown rice is a favorite of both standard diets and special diets prepared for individuals afflicted by celiac disease and/or those who are intolerant to other grains. Besides its nutritional value, brown rice is one of the excellent functional foods because it reduces risks of various chronic diseases and has a positive impact on overall health [214]. Scientific research has confirmed the health-promoting activities of brown rice, such as alleviation of pain and anxiety, standardization of both blood pressure and heart rate, suppression of liver damage, improvement of autonomic disorders and sleeplessness related to presenile or menopausal periods, inhibition of cancer cell proliferation, reduction of diabetes risk, and protection against oxidative stress [214–217].
3.2.8 Other Cereals
Millet is the oldest summer cereal crop used in human civilizations, together with wheat and barley. Its growing season is quite brief, lasting only 10 or 11 weeks. It can be cultivated in a wide area range [218, 219]. The species of millet are the staple cereal sources in Africa. The only species of millet grown for food consumption on a larger scale in northern countries such as Canada, the United States, and Europe is Panicum mili-aceum L. subsp. miliaceum, commonly referred to as proso millet or common millet [220, 221].
Millet contains carbohydrates at a proportion of 65%–75%, together with 15%–20% dietary fiber and 5%–10% protein [222, 223]. The levels of soluble fiber and insoluble fiber in millet are 2.5% and 19.5%, respectively [223, 224]. Millet is a valuable food in terms of its high ratios of minerals, most particularly calcium, iron, and phosphorus [223, 225]. It also contains significant levels of various polyphenols. Total polyphenol content has been reported to be between 37.76 and 50.54 ferulic acid equivalent mg/100 g dry matter in 8 dehulled varieties of millet and 53.31–106.23 ferulic acid equivalent mg/100 g dry matter in 8 wholegrain varieties [220, 221].
It is known that millet has various advantages for human health, such as making a contribution in preventing cancers and cardiovascular diseases, decreasing high blood pressure levels, decreasing the risks of heart disease, supplying gastrointestinal bulk and delaying gastric emptying, and exhibiting antioxidant and hypocholesterolemic properties due to the polyphenols and dietary fiber in its structure [34, 223, 226–228].
Sorghum bicolor (L.) Moench, simply known as sorghum, is the 5th most important cereal globally. The production of sorghum is generally more economical because it performs better than other cereals under several environmental stresses. Over 35% of the world’s sorghum is directly used for consumption by humans, while the remainder is utilized mostly for alcohol, animal feeds, and industrial products. The largest sorghum producer and exporter globally is the United States [229].
Sorghum’s chemical composition is, on average, 12.71% moisture, 3.10% fat, 11.46% protein, 1.55% ash, 2.05% fiber, and 71.19% total carbohydrates. Tannins are among the polyphenols known to reduce the nutritional quality of sorghum [230]. The tannin content of different sorghum varieties is about 0.23% catechin equivalents on dry basis [231, 232]. Sorghum contains high amounts of iron and zinc. Oleic acid (18: 1) and linoleic acid (18: 2) are also present as major fatty acids of sorghum [230].
Studies have reported that sorghum has various potential health and pharmaceutical benefits. These can be summarized as slow digestibility, anti-inflammatory, antioxidant, cholesterol-lowering, and anti-carcinogenic benefits [233–235].
Maize (Zea mays L.), the plant from which corn is obtained, is globally among the most important and popular agricultural crops [236, 237]. It is mainly considered as a source of feed (60%) and is also used as a source of human sustenance (24%), industrial products (starches) (14%), beverages (1%), and seeds (1%) [237–240]. About 9000 years ago, maize was encountered in the Mesoamerican region known as Mexico and Central America, and at that time it was called as wild grass or “teosinte” [241–243]. Today, it is cultivated in many places such as Africa, Middle Eastern countries, Pakistan and India, Brazil, Malaysia, the southern parts of the United States, and Turkey [243].
According to the studies of Qamar et al. [243], maize grains have moisture contents that range from 8.98% to 10.45%, ash contents from 0.81% to 1.35%, crude fiber contents from 0.79% to 2.78%, and crude protein contents from 11.05% to 12.79%. Reasonable amounts of flavonoid compounds and phenolic acids, including vanillic, coumaric, syringic, ferulic, and caffeic acids, can also be found in maize grains [244–247]. Minerals (Mg, K, P), vitamins (A, B, K, E), and carotenoids are among other nutrients and phytochemicals found in maize.
Increasing numbers of academic studies prove that frequently consuming maize can lower one’s risks of developing chronic diseases including type-2 diabetes mellitus, cardiovascular disease, or obesity, as well as improving digestive health [248].
Secale cereale L., or rye, is a low-yielding product that has long, weak straws [249, 250]. It tolerates both cold climates and less fertile soils. It is considered the main cereal in Northern and Central Europe, in areas in which wheat cannot be cultivated [251]. Although total rye production has decreased over the years, its usage in food products has grown somewhat since the 1990s [249, 250]. Annual rye production is about 18 million tons [252]. Approximately 1/3 of the rye produced worldwide is consumed as food by people. The rest of it is utilized as feed [249, 250].
Rye
