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THE EFFECT OF PROCESSING ON THE NUTRITIONAL VALUE OF FINGER MILLET ELEUSINE CORACANASEED
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The effect of processing on the proximate composition, antinutrient levels and mineral contents of finger millet seed Eleusine coracana were analyzed. Diets containing processed finger millet seed 71.4g per 100g feed were fed to four different groups of weaner rabbit for 56 days. Animals fed diet containing unprocessed finger millet seed were used as negative control group and animals fed diet containing casein standard protein were used as positive control group respectively. Effect of processing methods like soaking, boiling, fermenting and roasting on the finger millet seeds significantly plt;0.05 reduced the antinutrient substances like tannins, saponins, phytate and oxalate when compared with their values from the unprocessed finger millet seed. Protein quality parameters observed in the animals fed diet containing processed finger millet seeds like True Digestibity TD, Biological Value BV and Net Protein Utilization NPU increased in the following order; Roasted finger millet seed 98.410.55, 54.852.23 and 54.262.48, Boiled finger millet seed 95.570.93, 52.880.96 and 50.130.97, Fermented finger millet seed 95.180.28, 52.521.81 and 49.971.67, and Soaked finger millet seed 94.520.55, 50.630.96 and 47.992.46. In conclusion, the results indicated that roasting treatment is the best processing method on finger millet seed for better utilization of its protein content, while fermentation is best in reducing the antinutrients contents.
Finger millet Eleusine coracana, typically a tropical crop, belongs to the group of minor cereals. It is mainly consumed in India and Africa. It is an important cereal because of the excellent storage properties of the grain and the nutritive value, which is higher than that of rice and equal to that of wheat Van Wyk and Gericke, 2000. It is also a good source of micronutrients like calcium, iron, phosphorus, zinc and potassium.
Due to the presence of antinutrients in grains such as tannins and phytates, these micronutrients are less bioaccessable Harris and Burns 1978. Among millets, finger millet was reported to contain high amounts of tannins Ramachandra et al., 1977, ranging from 0.04 to 3.47 per cent cataechin equivalent. Poor iron availability represented by low ionizable iron in finger millets are due to their high tannin content which adversely affect the nutritional quality of the grains Udayasekhara Rao and Deosthale, 1988. Tannins reduced apparently digestibility of protein and energy Jansman et al., 1993. Cyanide readily and reversibly binds to a number of enzymes and proteins containing iron including haemoglobin, myoglobin, catalase and the cytochrome system Ahmed et al., 1996; Uvere, et al., 2000. Phytate interference with mineral absorption, especially calcium and zinc has been reported Doherty et al., 1982.
Oxalates affect calcium and magnesium metabolism Oke, 1969, and react with protein to form complexes which have an inhibitory effect on peptic digestion Oboh, 1986. Saponins act on the cardiovascular and nervous system as well as the digestive system Gestener, et al., 1966. Another antinutritional factor that affect the availability of some nutrients is phytate, a naturally occurring phosphorus compound which significantly influences the functional and nutritional properties of foods. It is the main phosphorus store in mature seeds. Phytate has a strong binding capacity, readily forming complexes with multivalent cations and proteins.
1.2 STATEMENT OF RESEARCH PROBLEM
Bioavailability of some nutrients in food supplements prepared from finger millet seeds is severely limited by the presence of antinutrients such as tannins, phytates, oxalates, cyanides and saponins. GibbsRussell et al., 1989.