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NUTRITIVE SIGNIFICANCE OF HUSKED AND DEHUSKED SEEDS OF AFRICAN BREADFRUIT AND CHARACTERIZATION OF ITS EXTRACTED OIL
J. O. Arawande, Ajayi Israel Oluwasanmi and Adewumi Bolorunduro Lanre
Department of Science Laboratory Technology, Rufus Giwa Polytechnic, Owo,Nigeria
This study reports the proximate and mineral composition of husked and dehusked seeds of African breadfruit, as well as physicochemical properties of oil extracted from the seeds. The moisture, ash and carbohydrate contents of husked seed are higher than that of dehusked seeds. While the crude protein, oil crude fibre and calorific values of dehusked seeds are higher than that of husked seeds. The husked seeds are richer in sodium, calcium, magnesium and iron than dehusked seeds while dehusked seeds are richer in zinc, copper, lead and potassium than husked seeds. The oil extracted from the seed of African breadfruit had acid value 2302 ± 0.005, free fatty acid (%lauric acid) 0.963=fc0.003, iodine value 17.43 ± 0.22, saponification value 257.60 ± 035, unsaponifiable matter 2.14±0.01, peroxide value 1,17±0.09, refractive index 1.468±0.000, relative density 0.905±0.012, colour 2R+13Y (23units), moisture impurity volatility 0.210 ± 0.001 and the oil was free from foreign and rancid odour and taste.
Keywords: Husked and dehusked seeds, African breadfruit, proximate composition, mineral composition, physicochemical properties and oil.
It is a common saying that a man is made up of what he eats, and what a man eats provides the nutrient that his body requires for daily activities. However, problem of correct intake of food or nutrient is being faced by both poor and rich. The poor lacks the money to purchase nourishing food while the rich eat excessively above the nutrient required by their body system. In a general sense, all food constituents are referred to as nutrient. Fruits are edible tissues resulting from the flower of a plant and usually containing the ripened seeds formed from the ovary of the flower (Herbert, 1978).
Many researchers have worked on the proximate composition and mineral contents of the seeds of African breadfruit. Oyenuga (1968) reported on average. Chemical composition of seeds of African
breadfruit on dry matter while FAO (1968) reported the chemical composition of the seeds of African breadfruit tree on wet matter. Edet et al (1984) worked on chemical evaluation of nutritive value of seeds of African breadfruit. Little or nothing has been done on the effect of dehusking (and husking) on the nutritional composition of the seeds since people eat both dehusked and husked seeds. This study is therefore tailored towards the nutritive values of husked and dehusked seeds of African breadfruit with the view of determining the nutritional potentials for human being and animals. It is also aimed at characterizing the oil extracted from the seeds.
Materials and Methods
Preparation of Husked and Dehusked Samples
The seeds of African breadfruit (Treculia africana) were purchased from local market, Akure, Ondo State. The seeds were sun dried before processing. The seeds have two coats, the outer coat was removed by squeezing and it was ground in an electric Kenwood blender into fine powder. The powdered sample was packed into an airtight polythene container and labeled husked sample. The dehusked sample was prepared by removing the two outer coats from the seeds by squeezing after it had been dried. It was ground into fine powder and packed into another airtight polythene container.
The moisture, crude protein, oil contents, ash, crude fibre and carbohydrate were determined by standard method of analysis (AOAC, 1999). The total carbohydrate was calculated by difference. The energy value (calorific) was calculated by multiplying the percentage carbohydrate by 4.1Kcal/g, oil by 9.5Kcal/g and protein by 5.5.Kcal/g. The sum total was taken as the total caloric energy value (Winberg, 1971), Analysis were determined in triplicate for each parameter.
The minerals analysis was determined in accordance with Standard method (AOAC, 1999). The minerals were obtained by dry ashing the powdered sample in a muffle furnace at 550°C until grey powder was obtained. The ash was dissolved in 10ml of 5M trioxonitrate(v) acid and the resulting solution was used for the mineral analysis using Perkin-Elmer, Atomic Absorption Spectrophotometer Model 372. (Perkin-Elnier, 1982).
The powdered samples was soaked in hexane in a closed container for 24 hours and it was shaken at regular interval of time. Thereafter, it was filtered using muslin cloth and the filterate was distilled in order to obtain the oil.
Oil analysis (Physico-chemical Properties)
The free fatty acid, acid value, iodine value, peroxide value, moisture impurity and volatility, saponification value, relative density, refractive index and unsaponifiable matter were determined using standard methods AOCS (1989). The colour was determined using Lovibond tintometer while odour and taste were determined organoleptically. All determinations were done in triplicate.
Results and Discussion
The result of proximate composition of husked and dehusked seeds of African breadfruit is depicted in Table 1. In both samples, carbohydrate was the highest (over 60%), which implies that the seed is a good source of carbohydrate and that it is an energy given food. Although the carbohydrate content of husked seed (64.95 ± 0.27) is higher than the carbohydrate content (58.13%) reported by Edet et al (1984) but lower than carbohydrate content (69.90%) reported by Okafor and Okolo for the same seed. The slight variation in this value may possibly be as a result of the different localities the plant is cultivated as well as difference in the level of drying of the seeds. The crude protein for dehusked seed (13.80 ± 0.14) was higher than that of husked seed (11.27 ± 0.18) because the two outer coats which have been removed contain cellulose thereby shooting up the crude protein and reducing the carbohydrate content of
dehusked seed. The protein content of both samples is higher than that of yellow yam (Dioscorea cayensis) (5.02%) and white yam (Disscorea rotundata) (5.16%) but lower than that of aerial yarn (Dioscorea bulbifera) (19.97%) as reported by Akindahunsi and Oboh (1998). The moisture content (9.56 ±0.10) and ash (3.16 ± 0.10) of husked seed are higher than moisture content (9.06 ± 0.09) and ash (2.41 ± 0.10) of dehusked seed. This is probably due to the presence of coat in the husked seed which prevents the loss of moisture
from the seed and also contain some inorganic minerals which shoot up the ash content over dehusked seed. The ash content of both dehusked and husked seeds of African breadfruit is higher than that of Pentaclethm macrophylla seed (1.1 ± 0.1.), Monodora myristical seed (0.9 ± 0.1), Afzelia africana seed (2.0 ± 0.1) and Tetracarpidium conophomm seed (1.8 ± 0.0) lower than that of Parkia biglohosa seed (4.0 ± 0.0), Irvingia gabonesis seed (7.8 ± 0.3) and Prosporis africana seed (4.2 ± 0.2), as reported by Oboh and Ekperigin (2004). The oil content of dehusked seeds (13.80 ± 0.14) is higher than the husked seeds (11.27 ± 0.06) but both values are lower when compared with the oil content of the seeds (19.0 ± 0.3 - 58.5 ± 0.4) considered above by Oboh and Ekperigin (2004). The oil, moisture, ash and crude fibre of both samples are less than 10% and their content are progressively decreased in the order of written. The calorific value (Kcal/g) of husked seed
(421.57 ± 2.59) is less than that of dehusked seed (436.35 ± 1.85). This implies that dehusked seeds have the propensity of supplying the body with greater energy than husked seeds when eaten.
The mineral contents (mg/lOOg) in the husked and dehusked seeds are as shown in Table 2. It was found that sodium, calcium, magnesium and iron contents in husked seed were higher than that of dehusked seed while potassium, lead, copper and zinc contents of dehusked seed were higher than that of husked seed. However, manganese, cobalt, nickel were not detected in both husked and dehusked seeds. Calcium was not detected in dehusked seed as well. The Recommended Dietary Allowance RDA for sodium, potassium, calcium, magnesium, iron, zinc and copper are 500mg, 2000mg, 1000-1300mg, 320-420mg, 10-15mg, 12-15mg and L5-3mg respectively (Ward law, 2000; Carroll & Karen, 2001). Sodium in both sample was high (1526 - 1581mg/100g) and above the RDA therefore people suffering from high blood pressure should reduce the intake of the seeds to one third where as people suffering from muscle cramps as a result of deficiency in sodium can increase their intake of the seeds. Eating the husked seed that contained 156mg/100g calcium will enhance bone and tooth strength thereby reducing the risk of osteoporosis and ricket in children. Iron is good for blood formation and its high value in husked seeds suggests that it will boost blood iron for hemoglobin and immune function of the body system. Dehusked seed contained mgner vmuc of zinc than husked seed, hence the high intake of dehusked seeds will prevent skin rash, diarrhea, poor growth and poor wound healing. Generally both samples are rich in minerals which are essential composition of body fluid balance, impulse conduction, normal development and maintenance of normal acid-base balance of the blood.
Table 3 shows the physico-chemical properties of oil extracted from seeds of African breadfruit. The oil has relative density 0.905 ± 0.012, refractive index 1.468 ± 0.000, colour 23 units (2Red + 13 Yellow) in V2 cell, acid value 2.302 ± 0.005, free fatty acid (% lauric acid) 0.963 ± 0.003, saponification value 257.60 ± 0.350,. unsaponifiable matter 2.14 ± 0.01, moisture impurity volatility 0.210 ± 0.001, iodine value 17.43 ± 0.22, peroxide value 1.17 ± 0.09 and it is free from foreign and rancid odour and taste. The iodine value of African breadfruit oil (17.43 ± 0.22) is lower than the iodine value of palm kernel oil (19.00) but the saponification value of extracted oil is higher than that of palm kernel oil (250.00) as reported by Howard (1997). Saponification value is a measure of mean molecular weight of glyceride molecule and the greater the saponification value, the lower the molecular weight (Wesis, 1983). Therefore, the molecular weight of glyceride molecule in oil examined is lower than that of palm kernel oil The low value of free fatty acid and acid value of the oil suggest that the oil is edible, although, it can be industrially to make soap because of its high saponification value. The low peroxide value of the oil indicates that the degree of unsaturation and the ability to become oxidatively unstable are reduced.
Table 1: Proximate Composition of Husked and Dehusked Seeds of African Breadfruit (g/100g)
Parameter Husked Seeds Dehusked Seeds
Moisture 9.56 + 0.10 9.06 ±0.09
Crude protein 11.27+0.18 13.80+0.14
Oil 9.82+0.06 11.02+0.04
Ash 3.16 ±0.10 2.41 ±0.10
Crude fibre 1.24 + 0.07 1.33 + 0.10
Total carbohydrate 64.95 ±0.27 62.38 + 0.17
Calorific value (Kcal/g) 421.57+2.59 436.35 + 1.85
Mean + Standard Deviation of triplicate determination.
Element Husked Seeds Dehusked Seeds
Potassium 1083.00 ±0.90 1343.00 ±0.40
Sodium 1581.00 ±0.78 1526.00 + 0.33
Calcium 156.00 + 0.60 ND
Magnessium 1537.00 ±0.50 1154.00 ±0.20
Lead 60.00 + 0.00 145.00 + 0.10
Manganese ND ND
Iron 789.00 ±0.40 432.00+0.50
Copper 540.00 ± 0.80 680.00+0.30
Cobalt ND ND
Nickel ND ND
Zinc 459.00 ± 0.20 735.00 ±0.40
ND= Not Detected
Mean ± Standard deviation of triplicate determination
Table 3: Physico-Chemical Properties of Oil Extracted from Seeds of African Breadfruit
Relative Density (25°C) 0.905 ±0.012
Refractive Index (40°C) 1.468 ±0.000
Colour (l/2 cell) Lovibond unit 2R + 13Y (23 units ) (where R = Red & Y= Yellow)
Odour and Taste Free from foreign and rancid odour and taste
Moisture, impurity & Volatility(MIV) 0.210 ±0.001
Acid Value (mgKOH/g) 2.302 ± 0.005
Free Fatty Acid (% Lauric Acid) 0.963 ± 0.003
Saponification Value (mgKOH/g) 257.60 ±0.350
Unsaponifiable Matter (g/kg) 2.14 ±0.010
Iodine Value (Wijs) 17.43+0.22
Peroxide Value (mEq/kg) 1.17 ±0.09
Mean ± Standard deviation in triplicate determination
The result obtained shows that dehusking of the African breadfruit seed increases the crude protein, oil, crude fibre and calorific value but decreases the moisture, ash and total carbohydrate. It is hereby
recommended that the obese should dehusk the seeds before eating in order not to aggravate the problem of obesity. The high content of calcium, magnesium, iron and low content of lead, copper, zinc and potassium in husked seed of African breadfruit indicates that it is better for children to eat husked seeds rather than dehusked seeds. The oil extracted is a close substitute for palm kernel oil because it is edible and it can also be used industrially for soap making. However, further research will be carried out on the possible anti-nutrient of the husked and dehusked seeds as well as determining the fatty acid composition of the oil extracted from the seed of African breadfruit.
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