The chemical composition of rice is influenced to some extent by genetic and environmental factors. The composition of Indian rice is; moisture, 10.9-13.8 proteins, 5.5-9.3; carbohydrates, 73.4-80.8; fiber, 0.2-1.0; and mineral matter, 0.8-2.0 percent. The germ, the per carp and the aleuronic layers, which are richer than endosperm, in nutrients like protein, mineral and vitamins are separated from the grain during milling along with the husk.

The major carbohydrate of rice is starch (72-75 per cent). Rice also contains some freee sugars like glucose, sucrose and dextrin. The protein content of rice is lower than that of wheat. The rice proteins are more rich in arginine compared to other cereal proteins. They are deficient in lysine and threonine. Most of the minerals present in rice are located in the pericarp and germ. Polished rice is poor in calcium and iron.

NUTRITIVE VALUE OF SORGHUM

Generally, sorghum has more protein that maize, a lower fat content and about the same amount and proportion of carbohydrate components. Minerals present in the grain are calcium, magnesium, potassium and iron. Sorghum protein is superior to wheat protein in biological value and digestibility. Sorghum is totally free from gluten, contains more fiber and micronutrients. As sorghum is digested slowly, it is an excellent health food for people suffering from diabetes in India.

Milling: Sorghum grains are processed by dry milling, wet milling and by fermentation. The dry milling process starts with the cleaning of grains. The cleaned grain is conditioned, by addition of water, to soften the endosperm, and milled by the conventional roller mills to separate the endosperm, germ and bran from each other. Another milling process for sorghum is ‘pearling’ or decortications. In this case cleaned grains are wetted by spraying water for 2-3 min. and immediately milled in rice huller, to remove a major part of the coarse fibre, pigment and photons, with minimum degree of cracking of the grain. A maximum of 12 per cent polishing can be carried out. This type of milling can give products rich in protein (up to 27 per cent), and which are also high in fat and give a high yield of ash, but are low in fibre. These products are used in the preparation of food products of high protein content.