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Comparative study of the chemical composition and mineral element content of Artocarpus heterophyllus and Treculia africana seeds and seed oils
Available online at www.sciencedirect.com
Bioresource Technology 99 (2008) 5125–5129
Short Communication
Comparative study of the chemical composition and mineral element content of Artocarpus heterophyllus and Treculia africana seeds and seed oils Ibironke Adetolu Ajayi
*
Industrial Unit, Chemistry Department, Faculty of Science, University of Ibadan, Ibadan, Oyo State, Nigeria Received 29 September 2006; received in revised form 4 September 2007; accepted 10 September 2007 Available online 23 October 2007
Abstract A comparative study of Artocarpus heterophyllus and Treculia africana seeds, both of Moraceae family, was carried out to establish their chemical compositions and evaluate their mineral element content in order to investigate the possibility of using them for human and or animal consumption and also to examine if there is a relationship between the properties of these seeds. A. heterophyllus and T. africana are rich in protein; their protein contents are higher than those from high protein animal sources such as beef and marine fishes. Both seeds have high carbohydrate content and could act as source of energy for animals if included in their diets. The oil contents of the seeds are 11.39% and 18.54% for A. heterophyllus and T. africana, respectively. The oils are consistently liquid at room temperature. The results of the physicochemical properties of the two seeds are comparable to those of conventional oilseeds such as groundnut and palm kernel oils and could be useful for nutritional and industrial purposes. The seeds were found to be good sources of mineral elements. The result revealed potassium to be the prevalent mineral elements which are 2470.00 ppm and 1680.00 ppm for A. heterophyllus and T. africana, respectively followed by sodium, magnesium and then calcium. They also contain reasonable quantity of iron, in particular A. heterophyllus 148.50 ppm. 2007 Elsevier Ltd. All rights reserved. Keywords: Moraceae; Artocarpus heterophyllus; Treculia africana; Chemical composition
1. Introduction A number of tropical plants within the rain forest and semi-arid zones of Nigeria bear fruits, some of which are edible, but with seeds which are largely discarded. Recent studies have shown that some of the seeds could find application as animal feeds, based on their nutritional values, and raw materials for paint formulation based on the amounts and nature of the oils contained in them (Adesomoju, 1987; Eromosele and Eromosele, 1993; Eromosele et al., 1994). Artocarpus heterophyllus and Treculia africana both belong to the Moraceae family. A. heterophyllus, also popularly called jack fruit, is an evergreen tree which has been *
Corresponding author. Tel.: +234 80750411770; fax: +234 2 241 2221. E-mail address: [email protected]
0960-8524/$ - see front matter 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.biortech.2007.09.027
introduced to many tropical countries and has been cultivated in the evergreen forest zone of the W. African region. The tree bears fruits which vary in size from 20–49 kg. The pulp is used in various ways; it can be eaten raw or processed into cans, jams and chitneys or dried (Burkill, 1985). The fruits can be eaten raw, salted as a pickle, cooked or as sweet (Cavalcante, 1991; Prance and Silva, 1975; Vaughan and Geissler, 1997). The leaves and stem barks have been used to treat anaemia, asthma, dermatosis, diarrhoea, cough and as an expectorant (Balbach and Boarim, 1990). The fruit seeds and trunk have been described as containing chemical compounds with aphrodisiac properties (Ferrao, 1999). A considerable phytochemistry is recorded. The fruit contains some quantity of proteins and amino acid. The seeds are starchy with high content of protein, calcium and thiamine. The variations of carbohydrates and the distribution of free sugar and fatty acid
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composition of different parts of ripe jackfruit varieties have been reported (Chowdhury et al., 1997 and Rahman et al., 1999). Maia et al. (2004) also reports the aroma varieties from two fruit varieties of jackfruit. T. africana Dec’ne sp. Africana is a forest tree up to 27 m high. It is known in English as bread, wild bread fruit or Africana bread fruit. The Igbos in Nigeria calls it mmri ukwa. It has been established that a fruit may contain about 1,500 seeds. They are aromatic and have a flavour much like groundnuts. They are eaten raw, roasted, boiled or fried, more usually to stews. The seed is reported by Ajiwe et al. (1995) to contain 20.83 ± 0.57% semi-drying oil. Near to 60% of the world’s food supply comes from rice, wheat and corn although 250,000 plant species have been described worldwide (Pimentel et al., 1977; Raven and Johnson, 1992). Certain seeds contain proteins and other nutritionally important components that could be used as alternatives for human and animal diets. The search for alternatives feed ingredients, especially for developed countries is of utmost importance, particularly because of the high cost of animal protein sources. Previous authors have done some work on the seed and seed flour of T. africana and A. heterophyllus (Akubor and Badifu, 2004; Fasasi and Fasasi 2004; Okwari et al., 2006) but no comparable study of the chemical composition and mineral element of these seeds have been carried out. In view of the properties and uses of A. heterophyllus and T. africana, the objective of the work is to carry out a comparative study of the chemical composition and mineral element content of A. heterophyllus and T. africana. The results obtained were then compared with those of conventional edible oils such groundnut and palm kernel oil in order to determine their suitability as edible oils. 2. Methods 2.1. Proximate composition of the seed The fruits of A. heterophyllus and T. africana were collected from the Botanical Garden, University of Ibadan. Part of the seeds of T. africana was bought from local markets in Ibadan, Nigeria. The oils were extracted from the seeds with a soxhlet extractor using petroleum ether (40– 60 C). The oils obtained, after distilling off the hexane, was stored in a labeled flask. All analyses were carried out in Chemistry Department, University of Ibadan except protein determination which was carried out in Human Nutrition Department of the same University. Moisture, oil, protein, ash and crude fiber contents of the seeds were analyzed according to AOAC (1990). Carbohydrate contents were determined by difference [100 (protein + crude fat + ash + crude fiber)]. 2.2. Physicochemical characteristics
(1984). The methods of analysis for free fatty acid, saponification, peroxide and acid values are as outlined by Ajayi et al. (2004a). Colour and state of the oils at room temperature were noted by visual inspection. The refractive indices of the oils were determined using the Abbe refractometer while the specific gravity which was done at room temperature was estimated by the use of a specific gravity bottle following the method of Ajayi et al. (2004b). 2.3. Metal composition The metal composition of the seeds was determined following the method used by Idouraine et al. (1996). One gram of each seed was dried – ashed in a muffle furnace at 550 C for 5 h until a white ash was obtained. The minerals were extracted from ash by adding 3 ml of concentrated HNO3 (63%). The digest was carefully filtered into 100 ml standard bottle and made up to mark with distilled water. Minerals were estimated with the use of an atomic absorption spectrophotometer (Perkin Elmer model 703, USA). The instrument was calibrated with standard solutions containing known amounts of the minerals being determined, using analytical reagents; results are expressed in parts per million of dry matter. 3. Results and discussion The present result showed the moisture, ash, protein, crude oil, crude fiber and carbohydrate contents of A. heterophyllus to be 2.78%, 6.72%, 20.19%, 11.39%, 7.10% and 51.82%, respectively while for T. africana the values are 3.78%, 5.56%, 27.44%, 18.54%, 8.20% and 36.48% (Table 1). The moisture content of A. heterophyllus is lower than the one reported by Singh et al. (1991). The seeds of A. heterophyllus and T. africana can store for a long period of time without spoilage since higher moisture content could lead to increasing microbial action (Onyeike et al., 1995). Bobbio et al. (1978) reported protein, crude lipids and carbohydrate contents of jackfruit seeds as 31.9%, 1.3% and 66.2%, respectively. Kumar et al. (1988) also reported comTable 1 Proximate composition (% dry matter) of A. heterophyllus, T. africana, groundnut and palm kernel seeds Parameter
Moisture Ash Crude protein (N · 6.25) Crude fat Crude fiber Carbohydrate a
Procedures for the determination of the iodine value (Wijs’ method) were those recommended by the AOAC
b c
Speciesa A. heterophyllusb
T. africanab
Groundnutc
Palm kernelc
2.78 6.72 20.19
3.78 5.56 27.44
4.45 2.77 26.50
14.26 1.50 6.94
11.39 7.10 51.82
18.54 8.20 36.48
40.83 – 25.40
54.18 – 23.10
Mean of triplicate determination. Present work. Onyeike and Acheru (2002).
I.A. Ajayi / Bioresource Technology 99 (2008) 5125–5129
position of seeds from two varieties of jackfruit. Protein, crude lipids and carbohydrate content were 17.8–18.3%, 2.1–2.5% and 76.1%, respectively. The protein content of A. heterophyllus reported by Bobbio et al. (1978) was very high; however the seeds were reported to have been collected from fruits of various varieties of jackfruit. The ash content of A. heterophyllus and T. africana are comparable and higher than those reported for P. aquatica and S. striata (Oliveira et al., 2000) but lower than those found in literature for naked seed squash line (Idouraine et al., 1996). Both A. heterophyllus and T. africana have high protein content which is higher than that of palm kernel seeds but similar to that of groundnut seeds. These concentrations suggest that the two seeds can contribute to the daily protein need of 23.6 g for adults as recommended by the National Research Council (1974). The proximate composition of A. heterophyllus in the present study is different from those found in literature. The difference can be contributed by variety difference, maturation of the seeds and environmental condition. These effects were already reported by Rahman et al. (1999). The oil yields for A. heterophyllus and T. africana which are 11.39% and 18.54%, respectively are higher than that reported for African yam bean with a fat content of 2.50% (Edem et al., 1990) while that of T. africana is close to that of soybean (Oyenuga, 1968). This indicates that the seed is a good oil seed. Both seeds could be good sources of edible oils that can be used in cooking (Ajayi et al., 2006). The results of the physical properties of oil extracts from the seeds investigated are shown in Table 2. The colours of the oils are yellow. Their state at room temperature 28 ± 2 C was generally liquid. The refractive indices of the oils are 1.452 and 1.463 for A. heterophyllus and T. africana, respectively. The results of the chemical properties of the oils are presented in Table 3. The total acidity, expressed as acid value of T. africana 10.04 mg KOH/g oil was much lower than that of A. heterophyllus 24.96 mg KOH/g oil. Both values are higher than the 2.77 mg KOH/g oil reported for groundnut oil. The peroxide value of 15.00 mg/g oil for A. heterophyllus is signifi-
Table 2 Physical properties of A. heterophyllus, T. africana, groundnut and palm kernel seeds Properties
State at RTd Colour Refractive index Melting point (C) a b c d
Speciesa A. heterophyllusb
T. africanab
Groundnutc
Palm kernelc
Liquid Yellow 1.452
Liquid Yellow 1.463
Liquid Yellow –
Liquid Yellow –
–
–
41.70
34.00
Mean of triplicate determination. Present work. Onyeike and Acheru (2002). RT = Room temperature.
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Table 3 Chemical properties of A. heterophyllus, T. africana, groundnut and palm kernel seeds Composition
Speciesa A. heterophyllusb
Acid value mg NaOH/g oil Saponification number mg KOH/ g oil Iodine value mg/ 100 g %FFA as oleic acidd Peroxide value mg/g oil Ester value mg KOH/g oil a b c d
T. africanab
Groundnutc
Palm kernelc
24.96
10.04
2.77
16.60
89.76
85.71
362.00
732.00
11.20
33.30
0.44 20.00
0.57 20.00
104.06
–
12.48 15.00
5.06 6.67
64.80
75.67
–
–
Mean of triplicate determination. Present work. Onyeike and Acheru (2002). FFA (%) = free fatty acid.
cantly higher than 6.67 mg/g oil of T. africana. Pearson (1976) reported that fresh oils usually have peroxide values lower than 10 mg/g oil and oils become rancid when the peroxide value ranges from 20.0 to 40.0 mg/g oil. Ojeh (1981) also reported that oils with high peroxide values are unstable and can easily become rancid. It can be inferred that T. africana seed oil can be kept for a long time without deterioration while that of A. heterophyllus might not. The iodine value 104.06 mg/100 g for A. heterophyllus places the oil in the semi-drying group. It is higher than the values for palm oil (Eka, 1989) and breadnut seed oil (Nwinuka et al., 2001). The iodine value of A. heterophyllus shows a feature which, according to Dosunmu and Ochu (1995), could favour the utilization of the oil in the paint industry. The saponification values of both oils are low; the oils are therefore unsuitable for soap production. The seeds from A. heterophyllus and T. africana appeared to be important sources of mineral elements (Table 4). Potassium was conspicuously the highest followed by sodium, magnesium and calcium. There were great variations in the mineral content of the seed samples. The potassium content of A. heterophyllus 2470.00 ppm and T. africana 1680.00 ppm are much higher than those for groundnut 162.00 ppm and palm kernel seeds (134.00 ppm). Potassium is the most important intracellular element; it is required for various physiological functions (Olaniyi et al., 1993). The values for sodium content for A. heterophyllus and T. africana are not different from each other. The seeds, seemingly being good sources of minerals, will supply the body with them if included in diet. Vegetables are known to supply the vitamins, iron, calcium, magnesium, zinc and other minerals that are important for human health and according to Anne (1979) and Schutlink et al. (1987), they are affordable source of these minerals and vitamins for African families.
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Table 4 Mineral concentrations (ppm of dry matter) of A. heterophyllus, T. africana, groundnut and palm kernel seeds Element
Calcium Magnesium Potassium Sodium Iron Zinc Copper a b c
Speciesa A. heterophyllusb
T. africanab
Groundnutc
Palm kernelc
190.00 240.00 2470.00 398.50 148.50 40.85 22.00
50.00 100.00 1680.00 383.75 85.50 17.85 13.50
– – 162.00 19.00 1.30 5.74 1.26
– – 134.00 14.70 1.32 3.20 1.62
Mean of triplicate determination. Present work. Onyeike and Acheru (2002).
The two seeds from Moraceae family, A. heterophyllus and T. africana, are quite rich in oil, protein, carbohydrate, and some mineral elements. The oil content of the seeds classifies them as average oil yielding. The knowledge of the carbohydrate and protein content of the seeds seems interesting for nutritional application. The oils could be utilized as a source of edible oil for human consumption. Acknowledgement The author wishes to acknowledge the Departments of Chemistry and Human Nutrition, University of Ibadan, Ibadan, Nigeria for making their facilities available. References Adesomoju, A.A., 1987. Fatty acid composition of the seed oil of Chlorophora excelsa. Bull. Chem. Soc. Niger. 12, 69–71. Akubor, P.I., Badifu, I.O., 2004. Chemical composition, functional properties and baking potential of African breadfruit kernel and wheat blends. Int. J. Sci. Technol. 39, 223. AOAC, 1984. Official methods of analysis, 14th ed. Association of Official Analytical Chemists, Arlington, VA. AOAC, 1990. Official Methods of Analysis, 15th ed. Association of Official Analytical Chemists, Arlington, VA. Ajayi, I.A., Dawodu, F.A., Adebowale, K.O., Oderinde, R.A., 2004a. A study of the oil content of Nigeria grown Monodora myristica seeds for its nutritional and industrial applications. Pak. J. Sci. Ind. Res. 47, 60– 65. Ajayi, I.A., Oderinde, R.A., Taiwo, V.O., Agbedana, E.O., 2004b. Dietary effects on growth, plasma lipid and tissues of rat fed with nonconventional oil of Telfairia occidentalis. J. Sci. Food Agric. 84, 1715– 1721. Ajayi, I.A., Oderinde, R.A., Kajogbola, D.O., Uponi, J.O., 2006. Oil content and fatty acid composition of some underutilized legumes from Nigeria. Food Chem. 99, 115–120. Ajiwe, V.I.E., Okeke, C.A., Agbo, H.U., 1995. Extraction and utilization of breadfruit seed oil (Treculia africana). Bioresource Technol. 53, 183–184. Anne, R., 1979. The role of wild foliage plants in the diet: a case study of Lushoto, Tanzania. Ecol. Food Nutr. 8, 87–93. Balbach, A., Boarim, D.S.F., 1990. As Frutas na Medicina Natural. Editora Missionaria, Sao Paulo. Bobbio, F.O., El-Dash, A.A., Bobbio, P.A., Rodrigues, L.R., 1978. Isolation and characterization of the physico-chemical properties of
the starch of jackfruit seed (Artocarpus heterophyllus). Cereal Chem. 55, 505–511. Burkill, H.M., 1985. The useful plants of West Tropical Africa vol. second ed. Royal Botanic Gardens, Kew, Surrey. Cavalcante, P.B., 1991. Frutas Comestiveis Da Amazonia. Museu Paraense Emilio Goeldi, Belem, Edtora CEJUP. Chowdhury, F.A., Rahman, M.A., Mian, A.J., 1997. Distribution of free sugars and fatty acids composition of different parts of jackfruit (Artocarpus heterophyllus). Food Chem. 60, 25–28. Dosunmu, M.I., Ochu, C., 1995. Physicochemical properties and fatty acid composition of lipids extracted from some Nigerian fruits and seeds. Global J. Pure Appl. Sci. 7, 45–50. Edem, D.O., Amugo, C.I., Eka, O.U., 1990. Chemical composition of yam beans (Sphenostylis sternocarpa). Trop. Sci. 30, 59–63. Eka, O.U., 1989. Review of Studies on the Nutritive Value and Uses of Oilseeds, Nigeria. University of Calabar Press. Eromosele, I.C., Eromosele, C.O., 1993. Studies on the chemical composition and physicochemical properties of seeds of some wild plants. Plants Foods Hum. Nutr. 43, 251–258. Eromosele, I.C., Eromosele, C.O., Akintoye, A.O., Komolafe, T.O., 1994. Characterization of oils and chemical analyses of the seeds of wild plants. Plants Food Hum. Nutr. 46, 361–365. Fasasi, E., Fasasi, K., 2004. Chemical properties of raw and processed breadfruit (Treculia africana). J. Food Agric. Environ. 2, ISSN: 14590263. Ferrao, J.E.M., 1999. Fruiticultura Tropical: Especies Com Frutos Comestiveis, vol. I. Instito de Investigacao Cientifica Tropical, Lisboa. Idouraine, A., Kohlhepp, E.A., Weber, C.W., 1996. Nutrient constituents from eight lines of naked seed squash. J. Agric. Food Chem. 44, 721– 724. Kumar, S., Singh, A.B., Abidi, A.B., Upadhyah, R.G., Singh, A., 1988. Proximate composition of jack fruit seeds. J. Food Sci. Tech. 25, 308– 309. Maia, J.G.S., Andrade, E.H.A., Zoghbi, M.B., 2004. Aroma volatiles from two varieties of jackfruit (Artocarpus heterophyllus L.). Food Chem. 85, 195–197. National Research Council, 1974. Recommended daily dietary allowance. Nutr. Rev. 31, 373–395. Nwinuka, N.M., Ogbonda, J., Ayalogu, E.O., 2001. Physicochemical characterization of breadnut (Artocarpus altilis) seed oil. Global J. Pure Appl. Sci. 7, 451–453. Ojeh, O., 1981. Effects of refining on the physical and chemical properties of cashew kernel oil. J. Fats Oils Tech. 16, 513–517. Okwari, O.O., Ofem, O.E., Ettarh, R.R., Eyong, E.U., 2006. Blood glucose level and lipid profile in rats fed on Treculia africana (Breadfruit) diet: A sub-chronic study. J. Health Biomed. Sci. 5, 21–25. Olaniyi, A.A., Ayin, J.S.K., Ogundaini, A.O., Olugbade, T.A., 1993. Essential Inorganic and Organic Pharmaceutical Chemistry. Shaneson C.I. Ltd., Ibadan , Nigeria. Oliveira, J.T.A., Vasconcellos, I.M., Bezerra, L.C.N.M., Silveira, S.B., Monteiro, A.C.O., Moreira, R.A., 2000. Composition and nutritional properties of seeds from Pachira aquatica Aubl, Sterculia striata St Hil et Naud and Terminalia catappa Linn. Food Chem. 70, 185–191. Onyeike, E.N., Olungwe, T., Uwakwe, A.A., 1995. Effect of heat treatment and defatting on the proximate composition of some Nigerian local soup thickeners. Food Chem. 53, 173–175. Onyeike, E.N., Ancheru, G.N., 2002. Chemical composition of selected Nigerian oilseeds and physicochemical properties of the oil extracts. Food. Chem. 77, 431–437. Oyenuga, V.A., 1968. Nigeria’s Food and Feeding Stuffs; Their Chemistry and Nutritive Value, third ed. University of Ibadan Press. Pearson, D.A., 1976. Chemical Analysis of Food, seventh ed. Churchill, Livingtone, Edinburg. Pimentel, D., Wilson, C., McCullum, C., Huang, R., Dwen, P., Flack, J., Tran, Q., Saltman, T., Cliff, B., 1977. Economic and environmental benefits of biodiversity. Bioscience 47, 747–757. Prance, G.T., Silva, M.F.da., 1975. Arvores de Manaus. Instito Nacional de Pesquisas da Amazonia, Manaus.
I.A. Ajayi / Bioresource Technology 99 (2008) 5125–5129 Rahman, M.A., Nahar, N., Jabbar, M.A., Mosihuzzaman, M., 1999. Variation of carbohydrate composition of two forms of fruit from jack tree (Artocarpus heterophyllus L.) with maturity and climatic conditions. Food Chem. 65, 91–97. Raven, P.H., Johnson, G.B., 1992. Biology. Mosby-Year Book, St. Louis.
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Schutlink, J.W., West, C.E., Pepping, F., 1987. Beta-carotene content of Tanzania food stuffs. East Afri. Med. J. 64, 368–371. Singh, A., Kumar, S., Singh, I.S., 1991. Functional properties of jack fruit seed flour. Lebensm-Will U Technol. 24, 373–374. Vaughan, J.G., Geissler, C., 1997. The New Oxford Book of Food Plants. Oxford University Press, New York.
Bioresource Technology 99 (2008) 5125–5129
Short Communication
Comparative study of the chemical composition and mineral element content of Artocarpus heterophyllus and Treculia africana seeds and seed oils Ibironke Adetolu Ajayi
*
Industrial Unit, Chemistry Department, Faculty of Science, University of Ibadan, Ibadan, Oyo State, Nigeria Received 29 September 2006; received in revised form 4 September 2007; accepted 10 September 2007 Available online 23 October 2007
Abstract A comparative study of Artocarpus heterophyllus and Treculia africana seeds, both of Moraceae family, was carried out to establish their chemical compositions and evaluate their mineral element content in order to investigate the possibility of using them for human and or animal consumption and also to examine if there is a relationship between the properties of these seeds. A. heterophyllus and T. africana are rich in protein; their protein contents are higher than those from high protein animal sources such as beef and marine fishes. Both seeds have high carbohydrate content and could act as source of energy for animals if included in their diets. The oil contents of the seeds are 11.39% and 18.54% for A. heterophyllus and T. africana, respectively. The oils are consistently liquid at room temperature. The results of the physicochemical properties of the two seeds are comparable to those of conventional oilseeds such as groundnut and palm kernel oils and could be useful for nutritional and industrial purposes. The seeds were found to be good sources of mineral elements. The result revealed potassium to be the prevalent mineral elements which are 2470.00 ppm and 1680.00 ppm for A. heterophyllus and T. africana, respectively followed by sodium, magnesium and then calcium. They also contain reasonable quantity of iron, in particular A. heterophyllus 148.50 ppm. 2007 Elsevier Ltd. All rights reserved. Keywords: Moraceae; Artocarpus heterophyllus; Treculia africana; Chemical composition
1. Introduction A number of tropical plants within the rain forest and semi-arid zones of Nigeria bear fruits, some of which are edible, but with seeds which are largely discarded. Recent studies have shown that some of the seeds could find application as animal feeds, based on their nutritional values, and raw materials for paint formulation based on the amounts and nature of the oils contained in them (Adesomoju, 1987; Eromosele and Eromosele, 1993; Eromosele et al., 1994). Artocarpus heterophyllus and Treculia africana both belong to the Moraceae family. A. heterophyllus, also popularly called jack fruit, is an evergreen tree which has been *
Corresponding author. Tel.: +234 80750411770; fax: +234 2 241 2221. E-mail address: [email protected]
0960-8524/$ - see front matter 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.biortech.2007.09.027
introduced to many tropical countries and has been cultivated in the evergreen forest zone of the W. African region. The tree bears fruits which vary in size from 20–49 kg. The pulp is used in various ways; it can be eaten raw or processed into cans, jams and chitneys or dried (Burkill, 1985). The fruits can be eaten raw, salted as a pickle, cooked or as sweet (Cavalcante, 1991; Prance and Silva, 1975; Vaughan and Geissler, 1997). The leaves and stem barks have been used to treat anaemia, asthma, dermatosis, diarrhoea, cough and as an expectorant (Balbach and Boarim, 1990). The fruit seeds and trunk have been described as containing chemical compounds with aphrodisiac properties (Ferrao, 1999). A considerable phytochemistry is recorded. The fruit contains some quantity of proteins and amino acid. The seeds are starchy with high content of protein, calcium and thiamine. The variations of carbohydrates and the distribution of free sugar and fatty acid
5126
I.A. Ajayi / Bioresource Technology 99 (2008) 5125–5129
composition of different parts of ripe jackfruit varieties have been reported (Chowdhury et al., 1997 and Rahman et al., 1999). Maia et al. (2004) also reports the aroma varieties from two fruit varieties of jackfruit. T. africana Dec’ne sp. Africana is a forest tree up to 27 m high. It is known in English as bread, wild bread fruit or Africana bread fruit. The Igbos in Nigeria calls it mmri ukwa. It has been established that a fruit may contain about 1,500 seeds. They are aromatic and have a flavour much like groundnuts. They are eaten raw, roasted, boiled or fried, more usually to stews. The seed is reported by Ajiwe et al. (1995) to contain 20.83 ± 0.57% semi-drying oil. Near to 60% of the world’s food supply comes from rice, wheat and corn although 250,000 plant species have been described worldwide (Pimentel et al., 1977; Raven and Johnson, 1992). Certain seeds contain proteins and other nutritionally important components that could be used as alternatives for human and animal diets. The search for alternatives feed ingredients, especially for developed countries is of utmost importance, particularly because of the high cost of animal protein sources. Previous authors have done some work on the seed and seed flour of T. africana and A. heterophyllus (Akubor and Badifu, 2004; Fasasi and Fasasi 2004; Okwari et al., 2006) but no comparable study of the chemical composition and mineral element of these seeds have been carried out. In view of the properties and uses of A. heterophyllus and T. africana, the objective of the work is to carry out a comparative study of the chemical composition and mineral element content of A. heterophyllus and T. africana. The results obtained were then compared with those of conventional edible oils such groundnut and palm kernel oil in order to determine their suitability as edible oils. 2. Methods 2.1. Proximate composition of the seed The fruits of A. heterophyllus and T. africana were collected from the Botanical Garden, University of Ibadan. Part of the seeds of T. africana was bought from local markets in Ibadan, Nigeria. The oils were extracted from the seeds with a soxhlet extractor using petroleum ether (40– 60 C). The oils obtained, after distilling off the hexane, was stored in a labeled flask. All analyses were carried out in Chemistry Department, University of Ibadan except protein determination which was carried out in Human Nutrition Department of the same University. Moisture, oil, protein, ash and crude fiber contents of the seeds were analyzed according to AOAC (1990). Carbohydrate contents were determined by difference [100 (protein + crude fat + ash + crude fiber)]. 2.2. Physicochemical characteristics
(1984). The methods of analysis for free fatty acid, saponification, peroxide and acid values are as outlined by Ajayi et al. (2004a). Colour and state of the oils at room temperature were noted by visual inspection. The refractive indices of the oils were determined using the Abbe refractometer while the specific gravity which was done at room temperature was estimated by the use of a specific gravity bottle following the method of Ajayi et al. (2004b). 2.3. Metal composition The metal composition of the seeds was determined following the method used by Idouraine et al. (1996). One gram of each seed was dried – ashed in a muffle furnace at 550 C for 5 h until a white ash was obtained. The minerals were extracted from ash by adding 3 ml of concentrated HNO3 (63%). The digest was carefully filtered into 100 ml standard bottle and made up to mark with distilled water. Minerals were estimated with the use of an atomic absorption spectrophotometer (Perkin Elmer model 703, USA). The instrument was calibrated with standard solutions containing known amounts of the minerals being determined, using analytical reagents; results are expressed in parts per million of dry matter. 3. Results and discussion The present result showed the moisture, ash, protein, crude oil, crude fiber and carbohydrate contents of A. heterophyllus to be 2.78%, 6.72%, 20.19%, 11.39%, 7.10% and 51.82%, respectively while for T. africana the values are 3.78%, 5.56%, 27.44%, 18.54%, 8.20% and 36.48% (Table 1). The moisture content of A. heterophyllus is lower than the one reported by Singh et al. (1991). The seeds of A. heterophyllus and T. africana can store for a long period of time without spoilage since higher moisture content could lead to increasing microbial action (Onyeike et al., 1995). Bobbio et al. (1978) reported protein, crude lipids and carbohydrate contents of jackfruit seeds as 31.9%, 1.3% and 66.2%, respectively. Kumar et al. (1988) also reported comTable 1 Proximate composition (% dry matter) of A. heterophyllus, T. africana, groundnut and palm kernel seeds Parameter
Moisture Ash Crude protein (N · 6.25) Crude fat Crude fiber Carbohydrate a
Procedures for the determination of the iodine value (Wijs’ method) were those recommended by the AOAC
b c
Speciesa A. heterophyllusb
T. africanab
Groundnutc
Palm kernelc
2.78 6.72 20.19
3.78 5.56 27.44
4.45 2.77 26.50
14.26 1.50 6.94
11.39 7.10 51.82
18.54 8.20 36.48
40.83 – 25.40
54.18 – 23.10
Mean of triplicate determination. Present work. Onyeike and Acheru (2002).
I.A. Ajayi / Bioresource Technology 99 (2008) 5125–5129
position of seeds from two varieties of jackfruit. Protein, crude lipids and carbohydrate content were 17.8–18.3%, 2.1–2.5% and 76.1%, respectively. The protein content of A. heterophyllus reported by Bobbio et al. (1978) was very high; however the seeds were reported to have been collected from fruits of various varieties of jackfruit. The ash content of A. heterophyllus and T. africana are comparable and higher than those reported for P. aquatica and S. striata (Oliveira et al., 2000) but lower than those found in literature for naked seed squash line (Idouraine et al., 1996). Both A. heterophyllus and T. africana have high protein content which is higher than that of palm kernel seeds but similar to that of groundnut seeds. These concentrations suggest that the two seeds can contribute to the daily protein need of 23.6 g for adults as recommended by the National Research Council (1974). The proximate composition of A. heterophyllus in the present study is different from those found in literature. The difference can be contributed by variety difference, maturation of the seeds and environmental condition. These effects were already reported by Rahman et al. (1999). The oil yields for A. heterophyllus and T. africana which are 11.39% and 18.54%, respectively are higher than that reported for African yam bean with a fat content of 2.50% (Edem et al., 1990) while that of T. africana is close to that of soybean (Oyenuga, 1968). This indicates that the seed is a good oil seed. Both seeds could be good sources of edible oils that can be used in cooking (Ajayi et al., 2006). The results of the physical properties of oil extracts from the seeds investigated are shown in Table 2. The colours of the oils are yellow. Their state at room temperature 28 ± 2 C was generally liquid. The refractive indices of the oils are 1.452 and 1.463 for A. heterophyllus and T. africana, respectively. The results of the chemical properties of the oils are presented in Table 3. The total acidity, expressed as acid value of T. africana 10.04 mg KOH/g oil was much lower than that of A. heterophyllus 24.96 mg KOH/g oil. Both values are higher than the 2.77 mg KOH/g oil reported for groundnut oil. The peroxide value of 15.00 mg/g oil for A. heterophyllus is signifi-
Table 2 Physical properties of A. heterophyllus, T. africana, groundnut and palm kernel seeds Properties
State at RTd Colour Refractive index Melting point (C) a b c d
Speciesa A. heterophyllusb
T. africanab
Groundnutc
Palm kernelc
Liquid Yellow 1.452
Liquid Yellow 1.463
Liquid Yellow –
Liquid Yellow –
–
–
41.70
34.00
Mean of triplicate determination. Present work. Onyeike and Acheru (2002). RT = Room temperature.
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Table 3 Chemical properties of A. heterophyllus, T. africana, groundnut and palm kernel seeds Composition
Speciesa A. heterophyllusb
Acid value mg NaOH/g oil Saponification number mg KOH/ g oil Iodine value mg/ 100 g %FFA as oleic acidd Peroxide value mg/g oil Ester value mg KOH/g oil a b c d
T. africanab
Groundnutc
Palm kernelc
24.96
10.04
2.77
16.60
89.76
85.71
362.00
732.00
11.20
33.30
0.44 20.00
0.57 20.00
104.06
–
12.48 15.00
5.06 6.67
64.80
75.67
–
–
Mean of triplicate determination. Present work. Onyeike and Acheru (2002). FFA (%) = free fatty acid.
cantly higher than 6.67 mg/g oil of T. africana. Pearson (1976) reported that fresh oils usually have peroxide values lower than 10 mg/g oil and oils become rancid when the peroxide value ranges from 20.0 to 40.0 mg/g oil. Ojeh (1981) also reported that oils with high peroxide values are unstable and can easily become rancid. It can be inferred that T. africana seed oil can be kept for a long time without deterioration while that of A. heterophyllus might not. The iodine value 104.06 mg/100 g for A. heterophyllus places the oil in the semi-drying group. It is higher than the values for palm oil (Eka, 1989) and breadnut seed oil (Nwinuka et al., 2001). The iodine value of A. heterophyllus shows a feature which, according to Dosunmu and Ochu (1995), could favour the utilization of the oil in the paint industry. The saponification values of both oils are low; the oils are therefore unsuitable for soap production. The seeds from A. heterophyllus and T. africana appeared to be important sources of mineral elements (Table 4). Potassium was conspicuously the highest followed by sodium, magnesium and calcium. There were great variations in the mineral content of the seed samples. The potassium content of A. heterophyllus 2470.00 ppm and T. africana 1680.00 ppm are much higher than those for groundnut 162.00 ppm and palm kernel seeds (134.00 ppm). Potassium is the most important intracellular element; it is required for various physiological functions (Olaniyi et al., 1993). The values for sodium content for A. heterophyllus and T. africana are not different from each other. The seeds, seemingly being good sources of minerals, will supply the body with them if included in diet. Vegetables are known to supply the vitamins, iron, calcium, magnesium, zinc and other minerals that are important for human health and according to Anne (1979) and Schutlink et al. (1987), they are affordable source of these minerals and vitamins for African families.
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Table 4 Mineral concentrations (ppm of dry matter) of A. heterophyllus, T. africana, groundnut and palm kernel seeds Element
Calcium Magnesium Potassium Sodium Iron Zinc Copper a b c
Speciesa A. heterophyllusb
T. africanab
Groundnutc
Palm kernelc
190.00 240.00 2470.00 398.50 148.50 40.85 22.00
50.00 100.00 1680.00 383.75 85.50 17.85 13.50
– – 162.00 19.00 1.30 5.74 1.26
– – 134.00 14.70 1.32 3.20 1.62
Mean of triplicate determination. Present work. Onyeike and Acheru (2002).
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