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The Chemical Composition of Four Legumes Consumed in Botswana
JOURNAL OF FOOD COMPOSITION AND ANALYSIS ARTICLE NO.
11, 329 –332 (1998)
FC980595
The Chemical Composition of Four Legumes Consumed in Botswana J. O. Amarteifio1 and D. Moholo Department of Basic Sciences, Botswana College of Agriculture, Private Bag 0027, Gaborone, Botswana Received February 24, 1998 Legumes are a good source of protein. However, there is inadequate documented information on the chemical composition of some legumes consumed in Botswana. Four of these legumes were analyzed for ash, carbohydrate, crude fat, fiber, and protein and selected minerals: Ca, Fe, K, P, and Na. The legumes analyzed were: bambara groundnut (Vigna subterranea), marama bean (Tylosema esculentum), mung bean (Vigna radiata), and tepary bean (Phaseolus acutifolius). The analyses were done using the AOAC analytical methods. Marama bean has the highest crude fat, protein, P, and Ca contents. The crude fat, protein, carbohydrate, and potassium contents of the four legumes varied significantly (P , 0.05). From the results these legumes have a good potential as food crops in Botswana. Their cultivation and utilization should be encouraged. This would positively contribute toward improving food security. © 1998 Academic Press Key Words: legumes; proximate analysis; minerals; Botswana.
INTRODUCTION Legumes have a high protein content and they are an important source of cheap protein in many African countries where animal protein is expensive. These seeds are second in importance to cereals as sources of food but they are two to three times richer in protein than cereals (National Academy of Sciences, NAS, 1979). They are often used in crop rotation and intercropping. In this project the chemical compositions of four legumes consumed in Botswana were studied. They were Phaseolus acutifolius (tepary bean), Tylosema esculentum (marama bean), Vigna radiata (mung bean), and Vigna subterranea (bambara groundnut). Production of bambara groundnut is concentrated in the northern and eastern parts of Botswana. Bambara groundnut occurs in the market more frequently than mung bean, tepary bean, and marama beans. The immature seeds of bambara groundnuts are boiled, salted, and either consumed on their own or mixed with sweet corn. The dried ripe seeds are pounded into flour and are made into different types of porridge. Mung bean and tepary beans are grown in the southern and central regions of Botswana. The mature seeds are boiled, salted, and eaten as a main dish. Mung beans are nutritious and highly digestible (Kay, 1979). The marama bean is a native to the Kgalagadi and the neighboring sandy regions of southern Africa (NAS, 1979). This plant is a creeper. The seeds are contained in pods that dehisce when dry. They are roasted and eaten as a snack. The plant grows wild in the Kgalagadi and it is a staple food of the Basarwa people. Bambara groundnut, mung bean, and tepary beans are cultivated in Botswana. Marama beans grow wild. These crops thrive in semiarid areas such as Botswana. Their cultivation 1
To whom reprint requests should be addressed. Fax: (267)328753. E-mail: [email protected]. 329
0889-1575/98 $25.00 Copyright © 1998 by Academic Press All rights of reproduction in any form reserved.
330
AMARTEIFIO AND MOHOLO
and use should therefore be encouraged. However, there is very little information about the chemical composition of these legumes grown in Botswana. The purpose of this study is to provide this information. The main objective was to find out quantitatively the crude fat, crude protein, crude fiber, ash, carbohydrate, and mineral contents of these legumes and also, to find out if they are significantly different from each other. METHODS The seeds of bambara groundnut (JB POP4(I)), marama bean, mung bean, and tepary bean were ground, respectively, using a Thomas–Wiley Model 4 laboratory mill. The ground seeds were then passed through a 2-mm sieve and dried at 70°C to constant weight. The crude fat, protein, and ash were estimated using AOAC (1996) methods. Carbohydrate was determined by difference. Four replicates were analyzed for each legume and the mean was calculated. For the determination of ash content 2 g samples was used. They were heated in preweighed crucibles in a muffle furnace (Labcon, Type RM7) for 2 h at 600°C. They were allowed to cool to room temperature in a desiccator and then weighed. The crude fat was extracted using petroleum ether (40 – 60) as solvent in a Sextec HT6 system manufactured by Tecator Ltd., Bristol, United Kingdom. Three grams of the samples was used. The analysis for fiber was according to Weende’s method (as specified by the manufacturer’s handbook) using a Fibretec System M manufactured by Tecator Ltd. For the protein determination the Kjeldahl method was used. Samples of 1.25 g were analyzed. The nitrogen determined was converted to protein by multiplying by 6.25. The apparatus used was manufactured by Gerhardt Laboratory Instruments, West Germany. The digested samples used for the protein determination were used for estimation of minerals. The minerals determined were Ca, Fe, P, K, and Na. Calcium and iron were estimated using an Atomic Absorption Spectrophotometer(GBC 908). Phosphorus was determined using an ultraviolet 160 spectrophotometer and potassium and sodium using a 410-Flame Photometer. The statistical design was a completely randomized design with pulse type as the only variable. The data were analyzed using a one-way ANOVA. RESULTS Table 1 gives the details of the results. The ash contents for bambara groundnut (4.4%) and mung bean (4.3%) were insignificantly different. Those for marama (3.7%) and tepary beans (3.8%) were not significantly different. However, those for bambara and mung beans were significantly different from those of marama and tepary beans. Tepary bean and bambara groundnut had the highest amounts of carbohydrate (63.8 and 63.5%, respectively). Marama bean had the lowest (24.1%). From the statistical analysis the carbohydrate, fat, protein, and K contents of each legume were significantly different (P , 0.05). The crude fiber content for bambara groundnut (5.2%) and tepary bean (4.9%) were insignificantly different. Similarly, those for marama (4.4%) and mung beans (4.3%) were not significantly different (P . 0.05). However, the contents for bambara groundnut (5.2%) and tepary bean (4.9%) were significantly different from those of marama (4.4%) and mung beans (4.9%).
331
FOUR LEGUMES OF BOTSWANA TABLE 1 The Composition of the Four Legumes Legume Nutrient g/100 g (mean 6 standard error) Ash Carbohydrate Crude fat Crude fiber Crude protein Minerals (mg/100 g) Iron Potassium Phosphorus Sodium Calcium
Bambara groundnut
Marama bean
Mung bean
Tepary bean
4.4 6 0.14 a 63.5 6 0.02 b 6.6 6 0.04 b 5.2 6 0.13 a 18.3 6 0.12 d
3.7 6 0.14 b 24.1 6 0.02 d 33.5 6 0.04 a 4.4 6 0.13 b 34.1 6 0.12 a
4.3 6 0.14 a 59.8 6 0.02 c 1.1 6 0.04 c 4.3 6 0.13 b 26.37 6 0.12 b
3.8 6 0.14 b 63.8 6 0.02 a 0.9 6 0.04 d 4.9 6 0.13 a 24.74 6 0.12 c
5.9 6 0.17 b 1240 6 12.8 a 296 6 19.7 b 3.7 6 0.29 b 78 6 4.7 b
4.9 6 0.17 c 776 6 12.8 d 397 6 19.7 a 4.1 6 0.29 b 152 6 4.7 a
6.8 6 0.17 a 1032 6 12.8 c 287 6 19.7 b 11.8 6 0.29 a 142 6 4.7 a
4.5 6 0.17 c 1093 6 12.8 b 304 6 19.7 b 3.8 6 0.29 b 88 6 4.7 b
Note. Means with the same letter are insignificantly different (P . 0.05).
The values determined for Ca in marama (152 mg/100 g) and mung beans (142 mg/100 g) were significantly different from those of bambara groundnut (78 mg/100 g) and tepary bean (88 mg/100 g). The results show that bambara groundnut has the highest amount of K,1240 mg/100 g, while marama bean has the lowest, 776 mg/100 g. The highest figure determined for sodium was 11.8 mg/100 g (mung bean) and the lowest 3.7 mg/100 g (bambara groundnut). The value for Na in mung bean was significantly different (P , 0.05) from those of bambara groundnut, marama, and tepary beans. The iron contents for bambara (5.9 mg/100 g), marama (4.9 mg/100 g), and mung beans (6.8 mg/100 g) were significantly different (P , 0.05), but those for marama (4.9 mg/100 g) and tepary beans (4.5 mg/100 g) were not significantly different. Marama bean contained the highest amount of P, 397 mg/100 g, and mung bean the lowest, 287 mg/100 g. The amount of phosphorus in marama bean was significantly different from those of bambara groundnut, mung, and tepary beans. DISCUSSION For bambara groundnut the crude protein, carbohydrate, crude fat and fiber and ash determined were similar to those reported by FAO(1982). Also the protein, fat, fiber, ash, Na, K, and Fe are in line with those reported by Amarteifio et al. (1997). However, Ca is lower than that reported by FAO (1982). The carbohydrate is 6.6 –12.3% higher than that reported by Amarteifio et al. (1997). The P content is comparable to that determined by Nwokolo (1996). The differences observed in this study compared with those of Amarteifio et al. (1997) may be due to the different landraces used. Bambara groundnut has the highest amount of K but the lowest amount of protein when compared to the other three legumes studied. In the case of mung bean the values obtained for protein, carbohydrate, fat, fiber, K, Ca, and Fe are within the range reported by Kay (1979). P is 53–58 mg lower. Na is similar to that determined by Duke (1983). Mung bean has the highest amount of Fe when compared to the other three legumes. This legume would be useful where a legume with high Fe is required.
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Values of the protein, carbohydrate, and ash determined in marama bean are similar to those reported (NAS, 1979). Fat is 9.3% lower than that reported by Kay (1979); also, the fiber is lower than that reported by Kay (1979). Data were not available for Na, K, P, Ca, and Fe for comparison. This plant grows wild in southern Africa and not much research has been done on it. However, it seems to have a great potential as a food and cash crop (Engels, 1984). The high protein and oil contents would provide a good source of protein and energy in the rural areas. The oil has a pleasant odor and taste (Engels, 1984) and can therefore be used in the food and cosmetics industries. Marama bean has the highest fat, protein, P, and Ca contents. The protein, carbohydrate, fat, fiber, and ash contents assessed in tepary bean are similar to those reported (Purseglove, 1977, NAS, 1979). These seeds had the lowest fat content and would therefore be useful if a low fat diet is required. CONCLUSIONS From the results of this study, it can be concluded that the carbohydrate, crude fat, crude protein, and potassium contents of the four legumes varied significantly. The cultivation and utilization of marama bean should be encouraged. More agronomic studies should be done on this legume with a view to cultivating it. Future studies could include amino acid and fatty acid contents of these legumes. They are a cheap source of nutrients and could be useful in formulating balanced diets. ACKNOWLEDGMENTS We thank the Botswana College of Agriculture for providing funds. The technical assistance provided by Mr. R. Kapata and Mrs. A. Fisher is appreciated. We gratefully acknowledge the assistance of Dr. T. Adogla-Bessa with statistical analysis.
REFERENCES Amarteifio, J. O., Sawula, G., and Gibbons, M. R. D. (1997). Composition of four landraces of Bambara groundnuts in Botswana. Trop. Sci. 37, 143–145. Association of Official Analytical Chemists (AOAC) (1996). Official Methods of Analysis. 16th Ed. Washington, DC. Duke, J. A. (1983). Handbook of Legumes of World Economic Importance. Plenum, New York. Engels, E. (1984). Morama. Bull. Agric. Res. Botswana 2, 93–97. Kay, D. E. (1979). Food Legumes. Crop Product Digest No. 3. Tropical Products Institute, London. National Academy of Sciences (1979). Tropical Legumes: Resources for the Future. Natl. Acad. Press, Washington DC. Nwokolo, E. (1996). Bambara groundnut (Vigna subterranea). In Legumes and Oilseeds in Nutrition. (E. Nwokolo and J. Smartt, Eds.), pp. 216 –221. Chapman & Hall, London. Purseglove, J. W. (1977). Tropical Crops: Dicotyledons, Vol. 1. Longmans, Green, London. United Nations Food and Agriculture Organisation (FAO) (1982). Legumes in Human Nutrition. FAO food and nutrition paper No. 20. Rome, Italy.
11, 329 –332 (1998)
FC980595
The Chemical Composition of Four Legumes Consumed in Botswana J. O. Amarteifio1 and D. Moholo Department of Basic Sciences, Botswana College of Agriculture, Private Bag 0027, Gaborone, Botswana Received February 24, 1998 Legumes are a good source of protein. However, there is inadequate documented information on the chemical composition of some legumes consumed in Botswana. Four of these legumes were analyzed for ash, carbohydrate, crude fat, fiber, and protein and selected minerals: Ca, Fe, K, P, and Na. The legumes analyzed were: bambara groundnut (Vigna subterranea), marama bean (Tylosema esculentum), mung bean (Vigna radiata), and tepary bean (Phaseolus acutifolius). The analyses were done using the AOAC analytical methods. Marama bean has the highest crude fat, protein, P, and Ca contents. The crude fat, protein, carbohydrate, and potassium contents of the four legumes varied significantly (P , 0.05). From the results these legumes have a good potential as food crops in Botswana. Their cultivation and utilization should be encouraged. This would positively contribute toward improving food security. © 1998 Academic Press Key Words: legumes; proximate analysis; minerals; Botswana.
INTRODUCTION Legumes have a high protein content and they are an important source of cheap protein in many African countries where animal protein is expensive. These seeds are second in importance to cereals as sources of food but they are two to three times richer in protein than cereals (National Academy of Sciences, NAS, 1979). They are often used in crop rotation and intercropping. In this project the chemical compositions of four legumes consumed in Botswana were studied. They were Phaseolus acutifolius (tepary bean), Tylosema esculentum (marama bean), Vigna radiata (mung bean), and Vigna subterranea (bambara groundnut). Production of bambara groundnut is concentrated in the northern and eastern parts of Botswana. Bambara groundnut occurs in the market more frequently than mung bean, tepary bean, and marama beans. The immature seeds of bambara groundnuts are boiled, salted, and either consumed on their own or mixed with sweet corn. The dried ripe seeds are pounded into flour and are made into different types of porridge. Mung bean and tepary beans are grown in the southern and central regions of Botswana. The mature seeds are boiled, salted, and eaten as a main dish. Mung beans are nutritious and highly digestible (Kay, 1979). The marama bean is a native to the Kgalagadi and the neighboring sandy regions of southern Africa (NAS, 1979). This plant is a creeper. The seeds are contained in pods that dehisce when dry. They are roasted and eaten as a snack. The plant grows wild in the Kgalagadi and it is a staple food of the Basarwa people. Bambara groundnut, mung bean, and tepary beans are cultivated in Botswana. Marama beans grow wild. These crops thrive in semiarid areas such as Botswana. Their cultivation 1
To whom reprint requests should be addressed. Fax: (267)328753. E-mail: [email protected]. 329
0889-1575/98 $25.00 Copyright © 1998 by Academic Press All rights of reproduction in any form reserved.
330
AMARTEIFIO AND MOHOLO
and use should therefore be encouraged. However, there is very little information about the chemical composition of these legumes grown in Botswana. The purpose of this study is to provide this information. The main objective was to find out quantitatively the crude fat, crude protein, crude fiber, ash, carbohydrate, and mineral contents of these legumes and also, to find out if they are significantly different from each other. METHODS The seeds of bambara groundnut (JB POP4(I)), marama bean, mung bean, and tepary bean were ground, respectively, using a Thomas–Wiley Model 4 laboratory mill. The ground seeds were then passed through a 2-mm sieve and dried at 70°C to constant weight. The crude fat, protein, and ash were estimated using AOAC (1996) methods. Carbohydrate was determined by difference. Four replicates were analyzed for each legume and the mean was calculated. For the determination of ash content 2 g samples was used. They were heated in preweighed crucibles in a muffle furnace (Labcon, Type RM7) for 2 h at 600°C. They were allowed to cool to room temperature in a desiccator and then weighed. The crude fat was extracted using petroleum ether (40 – 60) as solvent in a Sextec HT6 system manufactured by Tecator Ltd., Bristol, United Kingdom. Three grams of the samples was used. The analysis for fiber was according to Weende’s method (as specified by the manufacturer’s handbook) using a Fibretec System M manufactured by Tecator Ltd. For the protein determination the Kjeldahl method was used. Samples of 1.25 g were analyzed. The nitrogen determined was converted to protein by multiplying by 6.25. The apparatus used was manufactured by Gerhardt Laboratory Instruments, West Germany. The digested samples used for the protein determination were used for estimation of minerals. The minerals determined were Ca, Fe, P, K, and Na. Calcium and iron were estimated using an Atomic Absorption Spectrophotometer(GBC 908). Phosphorus was determined using an ultraviolet 160 spectrophotometer and potassium and sodium using a 410-Flame Photometer. The statistical design was a completely randomized design with pulse type as the only variable. The data were analyzed using a one-way ANOVA. RESULTS Table 1 gives the details of the results. The ash contents for bambara groundnut (4.4%) and mung bean (4.3%) were insignificantly different. Those for marama (3.7%) and tepary beans (3.8%) were not significantly different. However, those for bambara and mung beans were significantly different from those of marama and tepary beans. Tepary bean and bambara groundnut had the highest amounts of carbohydrate (63.8 and 63.5%, respectively). Marama bean had the lowest (24.1%). From the statistical analysis the carbohydrate, fat, protein, and K contents of each legume were significantly different (P , 0.05). The crude fiber content for bambara groundnut (5.2%) and tepary bean (4.9%) were insignificantly different. Similarly, those for marama (4.4%) and mung beans (4.3%) were not significantly different (P . 0.05). However, the contents for bambara groundnut (5.2%) and tepary bean (4.9%) were significantly different from those of marama (4.4%) and mung beans (4.9%).
331
FOUR LEGUMES OF BOTSWANA TABLE 1 The Composition of the Four Legumes Legume Nutrient g/100 g (mean 6 standard error) Ash Carbohydrate Crude fat Crude fiber Crude protein Minerals (mg/100 g) Iron Potassium Phosphorus Sodium Calcium
Bambara groundnut
Marama bean
Mung bean
Tepary bean
4.4 6 0.14 a 63.5 6 0.02 b 6.6 6 0.04 b 5.2 6 0.13 a 18.3 6 0.12 d
3.7 6 0.14 b 24.1 6 0.02 d 33.5 6 0.04 a 4.4 6 0.13 b 34.1 6 0.12 a
4.3 6 0.14 a 59.8 6 0.02 c 1.1 6 0.04 c 4.3 6 0.13 b 26.37 6 0.12 b
3.8 6 0.14 b 63.8 6 0.02 a 0.9 6 0.04 d 4.9 6 0.13 a 24.74 6 0.12 c
5.9 6 0.17 b 1240 6 12.8 a 296 6 19.7 b 3.7 6 0.29 b 78 6 4.7 b
4.9 6 0.17 c 776 6 12.8 d 397 6 19.7 a 4.1 6 0.29 b 152 6 4.7 a
6.8 6 0.17 a 1032 6 12.8 c 287 6 19.7 b 11.8 6 0.29 a 142 6 4.7 a
4.5 6 0.17 c 1093 6 12.8 b 304 6 19.7 b 3.8 6 0.29 b 88 6 4.7 b
Note. Means with the same letter are insignificantly different (P . 0.05).
The values determined for Ca in marama (152 mg/100 g) and mung beans (142 mg/100 g) were significantly different from those of bambara groundnut (78 mg/100 g) and tepary bean (88 mg/100 g). The results show that bambara groundnut has the highest amount of K,1240 mg/100 g, while marama bean has the lowest, 776 mg/100 g. The highest figure determined for sodium was 11.8 mg/100 g (mung bean) and the lowest 3.7 mg/100 g (bambara groundnut). The value for Na in mung bean was significantly different (P , 0.05) from those of bambara groundnut, marama, and tepary beans. The iron contents for bambara (5.9 mg/100 g), marama (4.9 mg/100 g), and mung beans (6.8 mg/100 g) were significantly different (P , 0.05), but those for marama (4.9 mg/100 g) and tepary beans (4.5 mg/100 g) were not significantly different. Marama bean contained the highest amount of P, 397 mg/100 g, and mung bean the lowest, 287 mg/100 g. The amount of phosphorus in marama bean was significantly different from those of bambara groundnut, mung, and tepary beans. DISCUSSION For bambara groundnut the crude protein, carbohydrate, crude fat and fiber and ash determined were similar to those reported by FAO(1982). Also the protein, fat, fiber, ash, Na, K, and Fe are in line with those reported by Amarteifio et al. (1997). However, Ca is lower than that reported by FAO (1982). The carbohydrate is 6.6 –12.3% higher than that reported by Amarteifio et al. (1997). The P content is comparable to that determined by Nwokolo (1996). The differences observed in this study compared with those of Amarteifio et al. (1997) may be due to the different landraces used. Bambara groundnut has the highest amount of K but the lowest amount of protein when compared to the other three legumes studied. In the case of mung bean the values obtained for protein, carbohydrate, fat, fiber, K, Ca, and Fe are within the range reported by Kay (1979). P is 53–58 mg lower. Na is similar to that determined by Duke (1983). Mung bean has the highest amount of Fe when compared to the other three legumes. This legume would be useful where a legume with high Fe is required.
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AMARTEIFIO AND MOHOLO
Values of the protein, carbohydrate, and ash determined in marama bean are similar to those reported (NAS, 1979). Fat is 9.3% lower than that reported by Kay (1979); also, the fiber is lower than that reported by Kay (1979). Data were not available for Na, K, P, Ca, and Fe for comparison. This plant grows wild in southern Africa and not much research has been done on it. However, it seems to have a great potential as a food and cash crop (Engels, 1984). The high protein and oil contents would provide a good source of protein and energy in the rural areas. The oil has a pleasant odor and taste (Engels, 1984) and can therefore be used in the food and cosmetics industries. Marama bean has the highest fat, protein, P, and Ca contents. The protein, carbohydrate, fat, fiber, and ash contents assessed in tepary bean are similar to those reported (Purseglove, 1977, NAS, 1979). These seeds had the lowest fat content and would therefore be useful if a low fat diet is required. CONCLUSIONS From the results of this study, it can be concluded that the carbohydrate, crude fat, crude protein, and potassium contents of the four legumes varied significantly. The cultivation and utilization of marama bean should be encouraged. More agronomic studies should be done on this legume with a view to cultivating it. Future studies could include amino acid and fatty acid contents of these legumes. They are a cheap source of nutrients and could be useful in formulating balanced diets. ACKNOWLEDGMENTS We thank the Botswana College of Agriculture for providing funds. The technical assistance provided by Mr. R. Kapata and Mrs. A. Fisher is appreciated. We gratefully acknowledge the assistance of Dr. T. Adogla-Bessa with statistical analysis.
REFERENCES Amarteifio, J. O., Sawula, G., and Gibbons, M. R. D. (1997). Composition of four landraces of Bambara groundnuts in Botswana. Trop. Sci. 37, 143–145. Association of Official Analytical Chemists (AOAC) (1996). Official Methods of Analysis. 16th Ed. Washington, DC. Duke, J. A. (1983). Handbook of Legumes of World Economic Importance. Plenum, New York. Engels, E. (1984). Morama. Bull. Agric. Res. Botswana 2, 93–97. Kay, D. E. (1979). Food Legumes. Crop Product Digest No. 3. Tropical Products Institute, London. National Academy of Sciences (1979). Tropical Legumes: Resources for the Future. Natl. Acad. Press, Washington DC. Nwokolo, E. (1996). Bambara groundnut (Vigna subterranea). In Legumes and Oilseeds in Nutrition. (E. Nwokolo and J. Smartt, Eds.), pp. 216 –221. Chapman & Hall, London. Purseglove, J. W. (1977). Tropical Crops: Dicotyledons, Vol. 1. Longmans, Green, London. United Nations Food and Agriculture Organisation (FAO) (1982). Legumes in Human Nutrition. FAO food and nutrition paper No. 20. Rome, Italy.