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Sorghum and millets do not contain vitamin A, although certain yellowendosperm varieties contain small amounts of 13-carotene, a precursor of vitamin A. No vitamin C is present in the raw millet grains.
Considerable variation in the grain composition of these cereals has been reported, particularly for sorghum and pearl millet (Hulse, Laing and Pearson, 1980; Jambunathan and Subramanian, 1988; Rooney and Serna-Saldivar. 1991 ) (Table 18). Genetic factors play a major part in determining grain composition. Environmental factors also have a role. In several cereal grains, including sorghum, an inverse correlation has been observed between grain yield and protein content (Frey, 1977). The protein content of the grain is also significantly and inversely correlated with its weight and starch content. On the other hand, the ash content and protein content of the sorghum grain are positively correlated with each other (Subramanian and Jambunathan, 1982).
Goswamy and co-workers (Goswamy, Sehgal and Sharma, 1969; Goswamy, Sharma and Gupta, 1969; Goswamy, Sehgal and Gupta, 1970; Goswamy, Sharma and Sehgal, ] 970) analysed a number of pearl millet varieties of African, American and Indian origin and observed that variations in protein, fat, total ash, calcium, phosphorus and iron were large but were similar in the three types. Singh et al. ( 1987) compared the grain composition of five pearl millet varieties, of which three were inbred lines with high protein content (14.4 to 19.8 percent) and two were normal-protein (9.9 to 11.3 percent) cultivars. In the five genotypes, the values for fat, crude fibre, total ash and starch content were within the normal ranges as reported by Goswamy and co-workers and others (Jambunathan and Subramanian, 1988). Further, the high-protein lines contained 60 percent more protein than the normal varieties but had 40 percent less carbohydrate and 20 percent less fat. The high-protein lines were also high in fibre.
TABLE 17: Nutrient composition of sorghum, millets and other cereals (per 100 g edible portion; 12 percent moisture)
|Food||Proteina (g)||Fat (g)||Ash (g)||Crude fibre (g)||Carhohydrate (g)||Energy (kcal)||Ca (mg)||Fe (mg)||Thiamin (mg)||Riboflavin (mg)||Niacin (mg)|
a N x 6.25.
Sources: Hulse. Laing and Pearson. 1980: United States National Research Council/National Academy of Sciences. 1982. USDA/HNIS. 1984.
TABLE 18: Chemical composition of sorghum and pearl millet genotypes from the world germplasm collection at ICRISATa
|Food||Protein (%)||Fat (%)||Ash (%)||Crude fibre (%)||Starch (%)||Amylose sugar||Soluble sugar||Reducing sugar||Calcium (mg/100g)||Phos
phorus (mg/100 g)
a All values except protein are expressed on a
Source: Jambunathan and Subramanian. 1988.
Differences in grain composition in genotypes of other millets have also been reported. In finger millet, the value ranges reported by Pore and Magar (1977) are protein, 5.8 to 12.8 percent; fat, 1.3 to 2.7 percent; total ash, 2.1 to 3.7 percent; and carbohydrate 81.3 to 89.4 percent. Variations in the mineral content of these varieties were also large. Differences in the protein and mineral composition of finger millet hybrids have also been reported by Babu, Ramana and Radhakrishnan (1987). In foxtail millet from the world germplasm collection the protein content ranged from 6.7 to 15 percent and the ash content from 2.06 to 4.81 percent (Dhindsa, Dhillon and Sood, 1982). Monteiro et al. (1988) observed similar variations in protein (11.1 to 15 percent), ash (1.1 to 1.6 percent), fat (4.7 to 6.3 percent) and carbohydrate (65 to 75.7 percent) in 12 cultivars of foxtail millet.
Environmental factors including agronomic practices affect grain composition. Grain protein and its amino acid composition in sorghum differ with the location at which the crop is grown (Deosthale and Mohan, 1970; Deosthale, Nagarajan and Visweswar Rao, 1972; Deyoe and Shellenberger, 1965). The level of nitrogen fertilizer also influences the quantity and quality of protein in sorghum (Deosthale, Nagarajan and Visweswar Rao, 1972; Waggle, Deyoe and Smith, 1967) and also in pearl millet (Deosthale, Visweswar Rao and Pant, 1972; Shah and Mehta, 1959). Warsi and Wright ( 1973) noted that application of nitrogen fertilizer increased the grain yield and protein. Higher protein in response to fertilizer nitrogen was mainly the result of increased accumulation of prolamin, a poor-quality protein, in the grain (Sawhney and Naik, 1969). The level of nitrogen fertilizer had no effect on the mineral composition of grain sorghum. However, the mineral content of the sorghum increased with increasing levels of phosphorus fertilizer (Deosthale, Nagarajan and Visweswar Rao, 1972). The mineral composition of sorghum grain was influenced more by location than by variety (Deosthale and Belavady, 1978). Other factors such as the density of the plant population, season, water and stress also contribute to variations in gram composition.
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