Technical paper Fruit nutritive composition of Maesobotrya barteri, an under-exploited tropical African tree Marc Nwosu OGBUAGU*, Basil AGU Chem. Dep., Michael Okpara Univ. Agric., Umudike, PMB 7267, Umuahia, Abia State, Nigeria ogbuagumn@yahoo.com Fruit nutritive composition of Maesobotrya barteri, an under-exploited tropical African tree. Abstract –– Introduction. In Nigeria, the species M. barteri is under-exploited although the tree is of both medicinal and nutritional importance. It bears succulent black-purple fruits that are edible and stain the tongue. The seeds are often with a conspicuous caruncle, with the endosperm present or absent. We studied the nutritive values of the fruit and seeds. Materials and methods. After sampling the fruits in a forest of Abia State, Nigeria, they were washed and opened. The seeds were removed from the succulent portion (pulp). Both pulp and seeds were dried in an oven at 65 °C for 5 h, before being ground to obtain powdery samples. The crude protein, moisture, crude fat, crude fiber, ash contents, total carbohydrate, vitamin contents (A, C, E, thiamine, riboflavin and niacin) and mineral elements were determined. Results and discussion. The analyses showed that both the fruit and seed of M. barteri are good sources of essential dietary nutrients. The values obtained are comparably higher than those reported for some common tropical African fruits. Nigeria / Maesobotrya barteri / fruits / seeds / proximate composition / vitamins / mineral content Composition nutritive du fruit de Maesobotrya barteri, un arbre tropical africain sous-exploité. * Correspondence and reprints Fruits, 2008, vol. 63, p. 357–361 © 2008 Cirad/EDP Sciences All rights reserved DOI: 10.1051/fruits:2008034 www.fruits-journal.org RESUMEN ESPAÑOL, p. 361 Résumé –– Introduction. Au Nigéria, l'espèce M. barteri est sous-exploitée bien que l'arbre ait une importance médicinale et alimentaire. Il porte des fruits pourpre-noir succulents qui sont comestibles et colorent la langue. Les graines présentent souvent une caroncule remarquable, avec présence ou absence d'endosperme. Nous avons étudié la valeur nutritive de ces fruits et graines. Matériel et méthodes. Après échantillonnage des fruits dans une forêt de l’État d’Abia (Nigéria), ceux-ci ont été lavés et ouverts. Les graines ont été séparées de la partie succulente (pulpe). Pulpe et graines ont été séchées dans un four à 65 °C pendant 5 h, avant d'être moulues pour obtenir les échantillons de poudre. La teneur en protéine brute, le taux d’humidité, les corps gras bruts, les fibres brutes, la teneur en cendres, les hydrates de carbone, la teneur en vitamines (A, C, E, thiamine, riboflavine et niacine) et les éléments minéraux des échantillons ont été déterminés. Résultats et discussion. Les analyses ont montré que le fruit et la graine de M. barteri sont de bonnes sources d’éléments nutritionnels essentiels. Les valeurs obtenues sont comparativement plus élevées que celles rapportées pour certains fruits tropicaux communs en Afrique. Nigéria / Maesobotrya barteri / fruits / graine / composition globale / vitamine / teneur en éléments minéraux Fruits, vol. 63 (6) 357 Article published by EDP Sciences and available at http://www.fruits-journal.org or http://dx.doi.org/10.1051/fruits:2008034 M.N. Ogbuagu, B. Agu 1. Introduction samples of the dried pulp and seed used for the tests. Nigeria is rich in a wide variety of plants that are of both medicinal and nutritional importance. However, most of these plant species have remained under-exploited because of lack of useful information on their potential as sources of substances that are vital to human health with respect to nutrition and medicine. One such plant species is Maesobotrya barteri. The crude protein was determined by using the Kjeldahl apparatus as described by James [4]. The moisture, crude fat (ether extract), crude fiber and ash contents were determined by the method of the AOAC [5]. The total carbohydrate was determined by estimation using the arithmetic difference described by James [4] and Pearson [6]. Vitamin A was determined by the method of the Association of Vitamin Chemists described by Kirk and Sawyer [7]. Vitamin C, thiamine, riboflavin and niacin were determined by the method of Barakat et al. [8]. Vitamin E was determined by the method described by Pearson [6]. The mineral elements – phosphorus, calcium, magnesium, potassium and sodium – were determined by various methods described by James [4]. M. barteri, a member of the family Euphorbiaceae, is the most widely distributed Maesobortrya species in Nigeria. It is an under-storey of high forest, with trees up to 10 m high. It is a rainforest plant occurring in Sierra Leone, Southern Nigeria and Western Cameroon [1]. M. barteri bears fruit from April to June, which is up to 1 cm long, ovoid and often distinctly pointed [2]. The fruits are succulent black-purple berries. They are edible and stain the tongue. The seeds are often with a conspicuous caruncle, with the endosperm present or absent. At present, some species of plants are used worldwide in the pharmaceutical, food, cosmetics and perfumery industries; for example, as flavoring agents and natural pigments [3]. For a very long time, M. barteri has been in use in the local communities for the treatment of diarrhea, stomachache, dysentery, urethral discharge, venereal disease, jaundice, cough, measles and others [2]. Our paper presents the nutritive values of the fruit and seeds of the M. barteri tree. 2. Materials and methods The fruits were collected in one of the forests in Ikwuano Local Government Area of Abia State, Nigeria, where the university is situated. Then, they were properly washed with water and opened. The seeds were carefully removed from the succulent portion (pulp). The outer covering of the fruits was carefully removed. Both pulp and seeds were dried in the oven at 65 °C for 5 h, then they were ground to obtain the powdery 358 Fruits, vol. 63 (6) 3. Results and discussion The analyses showed that both fruit and seeds of M. barteri are good sources of essential dietary nutrients. 3.1. Proximate composition The carbohydrate contents of the fruit (68.9%) and seed (64.0%) are quite high when compared with other common fruits (table I). The carbohydrate content of some fruits has been estimated at between (5.1 and 23.0) g·100 g–1 of dry matter [9]. High values have also been reported, such as 26 g·100 g–1 of dry matter for orange and 25 g·100 g–1 of dry matter for grape [10]. Because of the carbohydrates and the caloric value, fruits are usually recommended for weight-reducing diets as well as for providing energy for convalescing patients who often lack appetite during a period of ill health. The crude fiber contents of the fruit (7.06%) and seed (4.54%) are quite reasonable. Values of between 0.1% and 6.8% for selected fruits and between 0.5% and 5.2% for selected seeds have been reported [10]. Dietary fiber promotes bowel regularity and Fruit nutritive composition of M. barteri Table I. Proximate composition (% of dry matter) of pulp and seeds of Maesobotrya barteri fruit. Part considered Moisture Ash Fat Protein Fiber Carbohydrates Fruit pulp 6.65 Seed 3.85 5.24 7.40 11.40 7.06 68.90 3.85 14.30 13.30 4.54 64.01 Table II. Mineral composition of pulp and seeds of Maesobotrya barteri fruit. Part considered Ca Mg K Na P Fe Se (mg·100 g–1 of dry matter) (% of dry matter) Fruit pulp 50.77 62.40 32.27 36.40 312.11 8.47 0.40 Seed 9.35 88.80 53.20 57.07 162.17 4.87 0 enhances frequent waste elimination, including bile acids, sterols and fat [11]. Fiber is of benefit in diverticular disease [12]. Fiber also lowers cholesterol absorption and prevents the formation of plaques whose components are cholesterol, some fats and protein [13]. The protein levels of M. barteri fruit (11.40%) and seed (13.30%) are quite high. However, the protein content of fruits is generally low. Platt [14] reported protein values between 0.5% and 0.8% for citrus fruits (Citrus spp.), 2.0% for Cape gooseberry (Physalis peruviana) and 1.5% for mulberry (Morus alba). The protein values of the fruit and seed indicate that the fruit and seed are very good sources of protein. Fruits are not very good sources of fats and are usually recommended as part of a weight-reducing diet [15]. However, the fat content of M. barteri fruit (7.40%) and seed (14.3%) is quite reasonable when compared with Treculia africana (10.27%) and passion fruit (1.20%) [16]. High values have been reported for such fruits as avocado (Persea americana), 17% to 20% [17]. Very low values have been reported for such fruits as banana (0.3%), apple (0.4%), guava (0.4%) and traces for grape, mango and pawpaw [14]. 3.2. Mineral composition Both the fruit and seed of M. barteri are good sources of minerals (table II). The fruit is particularly rich in phosphorus (312.11 mg·100 g–1 of dry matter), magnesium (62.4 mg·100 g–1) and calcium (50.77 mg·100 g–1). Seed contents of magnesium (88.80 mg·100 g–1) and phosphorus (162.17 mg·100 g–1) are also reasonable. Selenium is present in the fruit but absent in the seed. Values as low as 9.0 mg of Ca·100 g–1, 15 mg of P·100 g–1, 10 mg of Mg·100 g–1, 17 mg of K·100 g–1, 0.50 mg of Na·100 g–1 and 0.2 mg of Fe·100 g–1 have been reported for citrus species [18]. These values indicate that the fruit and seed of M. barteri are better sources of dietary minerals when compared with citrus fruits. However, the K to Na ratio of the sample is not of nutritional benefit since a very high K to Na ratio has been reported to be of nutritional benefit [19], especially to people with high blood pressure who have to restrict their sodium intake. However, high-K foods are omitted in the diets of people with renal failure. The values of iron (Fe) in both M. barteri fruit (8.47 mg·100 g–1) and seed (4.87 mg·100 g–1) are very high. Iron is a component of Fruits, vol. 63 (6) 359 M.N. Ogbuagu, B. Agu Table III. Vitamins A, C and E, and thiamine, riboflavin and niacin composition (mg·100 g–1 of dry matter) of pulp and seeds of Maesobotrya barteri fruit. Part considered Vitamin A Vitamin C Vitamin E Thiamine Riboflavin Niacin Fruit pulp 6.17 361.40 0 0.06 0.04 0.40 Seed 12.57 22.30 13.26 0.02 0.01 0.24 hemoglobin and helps in oxygen transport; hence, it is important for human nutrition and health. Calcium (Ca) and phosphorus (P) help in building normal bones and teeth. Calcium also helps in cell wall formation and its absence may result in weak and stunted growth because of poor bone development [20]. Magnesium (Mg) is also used in bone formation, and muscle and nerve function. Vitamin E has a high value of 13.26 mg·100 g–1 in the seed of M. barteri but it is absent in the fruit. Vitamin E plays a role as an anti-oxidant. It protects the red blood cell membrane from damage and breakage (hemolysis). It also helps to improve vitamin A adsorption if the dietary intake of vitamin A is low; in addition, vitamin E is used to metabolize iron in the cell and helps maintain nervous tissues, immune and insulin function [26]. 3.3. Vitamins The fruit and seed of M. barteri are good sources of vitamins A, C (ascorbic acid) and E, and they contain thiamine, riboflavin and niacin too (table III). The vitamin A contents of both fruit (6.17 mg·100 g–1 of dry matter) and seed (12.57 mg·100 g–1) are very high when compared with mango fruit (0.20 mg·100 g–1) [21]. Vitamin A (retinol) is necessary for growth, good vision, healthy tissue and reproduction. Lack of vitamin A results in night blindness [22]. The main contribution of fruits and their products to nutrition is undoubtedly their supply of vitamins, most especially the antiscorbutic vitamins [23]. High values of 300 mg of ascorbic acid·100 g–1 of dry matter have been reported for guava, 112 mg·100 g–1 for pawpaw, 43 mg·100 g–1 for orange, 179.8 mg·100 g–1 for cashew [24] and 300 mg·100 g–1 for mango fruit [21]. Therefore, the value of 361.4 mg of ascorbic acid·100 g–1 found for the fruit of M. barteri is very reasonable. However, the value of 22.3 mg·100 g–1 observed for the seed is quite low. Vitamin C is useful in the treatment of common cold and control of other diseases such as prostrate cancer [25]. 360 Fruits, vol. 63 (6) Acknowledgement We thank Dr. Meregini, Forestry department, Michael Okpara University of Agriculture, Nigeria, for the identification of the M. barteri fruits. References [1] Keay R.W.J., Trees of Nigeria, Clavendon Press Oxford, UK, 1989. [2] Dalziel J.M., The useful plants of tropical West Africa, Crown Overseas Agents Colon., London, UK, 1948. [3] Frantisek S., The natural guide to medicinal herb plants. Tiger Books Int., Twickenham, UK, 1998. [4] James C.S., Analytical chemistry of foods, Chapman and Hall, NY, USA, 1995. [5] Anon., Official methods of analysis, Assoc. Off. Anal. Chem. (AOAC), 15th ed., Washington D.C., USA, 1990. [6] Pearson D., The chemical analysis of foods, 7th ed., Churchill Livingstone, Edinburgh, UK, 1976. [7] Kirk R.S., Sawyer R., Pearson’s composition and analysis of foods, 9th ed., Longman Sci. Tech. Group, UK, 1991. Fruit nutritive composition of M. barteri [17] Ihekoronye A.L., Ngoddy P.O., Integrated food science and technology for the tropics, Macmillan Publ., London, UK, 1985. [8] Baraket M.Z., Shehab S.K., Daswish N., Zaherymy E.I., Determination of ascorbic acid from plants, J. Anal. Biochem. 53 (1973) 225–245. [9] Watt B.K., Merrill A.L., Composition of foods, Agric. Handb. No. 8, Consum. Food Econ. Res. Serv. US. Dep. Agric., USA, 1963. [18] Reuther W., Webber H.J., Batchelor L.D., The citrus industry, vol. I: History, world distribution, botany and varieties (revis. ed.), Univ. Calif., Div. Agric. Sci., Berkeley, USA, 1967. [10] Osee H., Bennion M., Introductory foods, 3rd ed., The MacMillan Co., Collier-MacMillan Ltd., London, UK, 1970. [19] Meneely G.B., Barttablee H.D., Sodium and potassium, Nutr. Rev. 34 (1976) 225–235. [11] Osborne D.R., Voogt P., Calculation of caloric value in the analysis of nutrients in roots, in: Osborne D.R., Voogt P. (Eds.), Analysis of nutrients in roots, Acad. Press., NY, USA, 1978, pp. 239–240. [12] Akobundu E.N.T., Healthy foods in human nutrition, J. Sustain. Agric. Environ. (1999) 1–7. [13] Scala J., Fiber: the forgotten nutrients, Food Technol. 20 (1) (1974) 34–36. [14] Platt B.S., Tables of representative values of foods commonly used in tropical countries, HMSO, Med. Res. Counc., spec. rep. ser., No. 302, London, UK, 1962. [15] Umoh I.B., Fats in fruits, in: Nutritional quality of plant foods, Osagie A.U., Eka O.U. (Eds.), Post harvest research unit, Dep. Biochem., Univ. Benin, Nigeria, 1998. [16] Ekpeyong T.E., Chemical composition and amino acid content of African breadfruit (Treculia africana), Food Chem. 17 (1985) 39–64. [20] Ekpa O.D., Nutrient compositions of three Nigerian medicinal plants, Food Chem. 57 (1996) 229–232. [21] Vickery M.L., Vickery B., Plant products of tropical Africa, Macmillan Press Ltd., London, UK, 1979. [22] Wardlaw G.M., Contemporary nutrition issues and insights, 4th Ed., McGraw Hill, Boston, USA, 2000. [23] Mapson L.W., Vitamins in fruits, in: Hulme A.C. (Ed.), The biochemistry of fruits and their products, vol. 1, Acad. Press, London, UK, 1970, pp. 369–383. [24] Onyenuga V.A., Nigerian foods and feeding stuffs. Their chemistry and nutritive value, Ibadan Univ. Press, Ibadan, Nigeria, 1968. [25] Okogun J.I., The Nigerian battle against HIV/ AIDS. The ignored but vital chemistry impute, Chem. Nigeria 2 (2002) 9–11. [26] Wardlaw G.M., Kessel M., Perspectives in nutrition, 5th Ed., McGraw Hill, NY, USA, 2002. Composición nutritiva del fruto de Maesobotrya barteri, un árbol tropical africano poco explotado. Resumen –– Introducción. En Nigeria, la especie M. barteri se explota poco, a pesar de la importancia medicinal y alimentaria que posee el árbol. Éste produce suculentos frutos de color negro-púrpura que son comestibles y colorean la lengua. Las semillas presentan a menudo un distinguido carúnculo, con la presencia o ausencia de endosperma. Estudiamos el valor nutritivo de estos frutos y semillas. Material y métodos. Tras un muestreo de los frutos en un bosque del estado de Abia (Nigeria), éstos se lavaron y se abrieron. Se separaron las semillas de la parte suculenta (pulpa). Se secaron la pulpa y las semillas en un horno a 65 °C durante 5 h, antes de ser molidos para obtener las muestras en polvo. Se determinaron el contenido en proteína bruto, el índice de humedad, los cuerpos grasos brutos, las fibras brutas, el contenido en cenizas, los hidratos de carbono, el contenido en vitaminas (A, C, E, tiamina, riboflavina y niacina) así como los elementos minerales. Resultados y discusión. Los análisis mostraron que el fruto y la semilla de M. barteri son buenas fuentes de elementos nutricionales esenciales. Los valores obtenidos son más elevados en comparación con aquellos aportados por ciertos frutos tropicales comunes en África. Nigeria / Maesobotrya barteri / frutas / semilla / composición aproximada / vitaminas / contenido mineral Fruits, vol. 63 (6) 361