International Journal of Applied Agricultural Research ISSN 0973-2683 Volume 5 Number 3 (2010) pp. 291–300 © Research India Publications http://www.ripublication.com/ijaar.htm Studies on the Proximate and Mineral Composition of Three Varieties of Lablab Beans (Lablab Purpureus) *K.O. Soetan1 and M.A. Fafunso2 1Department of Veterinary Physiology, Biochemistry and Pharmacology,University of Ibadan, Nigeria 2Department of Biochemistry, University of Ibadan, Nigeria *Corresponding Author’s E-mail: [email protected] Abstract The proximate and mineral composition of three varieties of lablab beans (Lablab purpureus) were studied. The three varieties used for this study were Rongai brown (PI509 114), Rongai White (NAPRI 4) and Highworth black (Grif 12293). Rongai brown variety had the highest concentration of crude protein, crude fat, ash and of gross energy. There were significant differences (P< 0.05) in the crude protein, crude fibre and the nitrogen free extracts in all the three varieties of the lablab beans. Potassium, phosphorus, magnesium and iron were appreciably high in all the three varieties while calcium and sodium concentrations were low. It is concluded that the lablab beans can be used as a source of dietary proteins especially in developing and under developed countries where consumption of animal protein may be limited as a result of economic, social, cultural or religious factors. Keywords: Proximate, mineral composition, Lablab purpureus. Introduction The high cost of animal protein has directed interest towards several leguminous seed proteins as potential sources of vegetable protein for human food and livestock feed (Esenwah and Ikenebomeh, 2008). Legumes are generally well adapted to a wide range of climates and environmental conditions. In Nigeria, an important factor limiting the rapid development of the livestock industry is the increasing unavailability and consequent high cost of the conventional feed ingredients of protein source like soyabean and groundnut cake (Bawa et al., 292 K.O. Soetan and M.A. Fafunso 2003). This has threatened the potential for increasing animal protein production, which is in short supply. Most common plant protein sources for human consumption are also the major sources of plant proteins for livestock feed formation.This results in a high cost of conventional plant protein foods and a generally substandard feed production (Adegbola, 1990). Of the thousand known legume species, only few have been extensively promoted and used. Many other potential legumes are still marginally unknown (Osman, 2007). These potential legumes might be of great importance in many zones of developing countries where there is a pressing need for food sources of high energy and good quality protein. The lablab beans (Lablab purpureus) is one of the lesser known legumes of arid and semi arid land (Osman, 2007). The bean is classified by the National Academy of Science (NAS) as potential source of protein that has not been explored yet. In view of this, the use of underutilized legume grains that have low preference as human food and are obtainable at relatively lower costs are being investigated (Bawa et al., 2003). Lablab seed (Lablab purpureus) is an example of such unconventional and under-utilized protein source. Lablab seed has low preference as human food (Bawa et al., 2003). Molina et al., (1977) have emphasized the need for vigorous research on non-conventional legumes for use in food preparations as protein sources. There has been only limited studies on the use of seeds as livestock feed. Presently, there is much interest in the cultivation of lablab crop because of its attribute as a dual-purpose legume (Ogundipe et al., 2003). Lablab bean can be used as seeds for human and livestock consumption and as forage for livestock (Henderiksen and Myles, 1980; Kiflewahid, 1986). L. purpureus looks promising as the legume of the future for both ruminants and monogastric nutrition (Ogundipe et al., 2003). Although the importance of forage legumes in the production of small ruminants in the rural tropics has been emphasized, information on their compositional analysis remains scanty (Aletor and Omodara, 1994). This study therefore aims at investigating the proximate and mineral composition of lablab beans, an under-utilized legume seed. Materials and Methods Materials The three varieties of the L. purpureus seeds used for this study are Rongai brown (PI509 114), Rongai white (NAPRI 4) and Highworth black (Griff 12293) obtained from the RCMD unit of the Internatitional Institute for Tropical Agriculture (I.I.T.A.), Ibadan, Nigeria. Analytical Procedure The proximate analysis of the air-dried seeds were determined by standard methods (AOAC, 1999). These include the determination of crude protein, crude fat, crude fibre, ash, gross energy, moisture content, dry matter and the nitrogen free extract. The minerals analysed include sodium, potassium, calcium, phosphorus, magnesium, iron and manganese. The sodium and potassium contents were determined by flame photometry (Jenway Limited, Donmow Essex, UK) and phosphorus was determined Studies on the Proximate and Mineral Composition 293 by the vanado-molybdate method (AOAC, 1995). Calcium, magnesium, iron and manganese were determined after wet digestion with a mixture of nitric,sulphuric and perchloric acid using atomic absorption spectrophotometer (Buck Scientific,East Norwalk,CT,USA). Statistical Analysis The analysis were done in triplicates. The data obtained were expressed as mean + standard error of the means (mean + SEM). Significant differences between means were determined by the student t-test (Bailey, 1992). Results The results of the proximate analysis is presented in table 1 and that of the mineral analysis is presented in table 2. Table 1: The Proximate Analysis of the three varieties of L. purpureus seeds. Sample %Crude %Crude %Crude % Ash % Nitrogen Gross %Dry % Moisture Protein Fat Fibre Free Extract Energy Matter (Kcal/g) Rongai 24.15 ±0.23 9.74± 0.74 12.69 ± 0.12 4.28 ±0.15 39.27 ± 0.40 3.10 ±0.15 89.96±0.31 10.04±0.21 Brown Rongai 23.10±0.80 9.56±0.38 13.12 ±0.15 3.97±0.15 40.29±0.15 2.93±0.59 90.04±0.40 9.96±0.04 White Highworth 22.75±0.53 9.63±0.85 12.98±0.15 4.12±0.12 40.39±0.38 3.00±0.26 89.87±0.19 10.13±0.19 Black Mean + SEM 23.33 + 0.52 9.64 + 0.65 12.93 + 0.14 4.12 + 0.14 39.93 + 0.31 3.01 +0.33 89.96 + 0.33 10.04 + 0.15 Rongai brown records the highest crude protein of 24.15% while highworth black records the least having 22.75%.For crude fat, rongai brown has the highest of 9.74% while rongai white has the least of 9.56%.For crude fibre, rongai white has the highest of 13.12% while rongai brown has least of 12.69%.For the Ash content, rongai brown has the highest of 4.28% while rongai white has the least of 3.97%. Nitrogen Free extract shows that highworth black has the highest of40.39% while rongai brown has the least of 39.27%. For Gross energy rongai brown has the highest having 3.10Kcal/g while rongai white has the least of 2.93Kcal/g.Dry matter reveals that rongai white has the highest of 90.04% while highworth black has the least of 89.87%.The moisture content reveals that the highworth black has the highest of 10.13% while the rongai white has the least of 9.96%. 294 K.O. Soetan and M.A. Fafunso Table 2: The Mineral Elements in the three varieties of L. purpureus seeds. Sample Mg% Ca% Na% K% Mn% P% Fe ppm Rongai White 0.34+0.02 0.67+0.01 0.18+0.01 1.53+0.01 0.08+0.01 0.48+0.01 157.0+1.01 Rongai Brown 0.34+0.02 0.67+0.01 0.18+0.01 1.53+0.01 0.08+0.01 0.48+0.01 157.0+1.01 Highworth 0.34+0.01 0.71+0.01 0.17+0.01 1.59+0.03 0.05+0.01 0.55+0.07 168.0+0.01 Black Mean + SEM 0.33+0.01 0.70+0.01 0.17+0.00 1.57+0.02 0.07+0.01 0.49+0.03 160+2.71 Discussion The search for protein sources is of great importance in the developing world where the population is growing at an accelerated rate. Plant proteins, such as legumes, will certainly play an important role in meeting the protein requirement of man as well as feeding his livestock (Apata, 1990). Among the plant species, grain legumes are considered as the major source of dietary proteins (Esenwah and Ikenebomeh, 2008). Legumes are important sources of proteins, carbohydrates, dietary fiber and minerals consumed worldwide (Osman, 2007). The results obtained show that the crude protein content of the 3 varieties of L. purpureus seeds were quite high ranging between 22.75 and 24.15%. The Rongai brown variety has the highest crude protein value of 24.15%, followed by Rongai white having 23.10% and Highworth black having the least value of 22.75%. These values for the 3 varieties compare favourably with those values reported by Oyenuga,(1968) for cowpea seeds, pigeon pea, water melon (unshelled bambara variety) and water melon, (unshelled serese variety) which are 24.67%, 23.77%, 24.36% and 23.55% respectively. Adrain and Helias-Frangner, (1964) obtained crude protein contents of 23% for bambara groundnut (Voandzeia sibterranea), 24.30% for the hyacinth bean and 17.45% for the cowpea (Vigna unguiculata), all from Senegal. The results obtained for the crude protein also agree with the finding of Amirshani and Tavakoli, (1970), who obtained an average protein content of 24.28% and the range of 22.45 to 27.25% based on 47 varieties of cowpea.