Research & Reviews: Journal of Food and Dairy Technology
MenuISSN: 2321-6204
ISSN: 2321-6204
+1-845-458-6882Omosuli SV*
Department of Food Science and Technology, Rufus Giwa Polytechnic, P.M.B 1019Owo, Ondo State, Nigeria
Received date: 22 October 2013 Accepted date: 28 December 2013
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The crude oil of Akee apple (Blighia sapida) seed was extracted by solvent extraction process. The oil was analysed for physical, chemical and fatty acid composition. The physical assessment gave the following results: yield(15.26%), specific gravity (0.85), colour (14units), moisture (0.48%), melt point (15oC), Smoke point (1350C), flash point (1700C), and Fire point (250C).The chemical properties obtained were; acid value (57.22mgKOH/g), free fatty acid (28.61% Oleic), saponification value (245.43mgKOH/g), peroxide value (6.40Meq/kg) and iodine value (22.84Wijs). Fatty acids detected and their values were myristic acid (0.28%), palmitic acid (16.41%), margaric acid (0.36%), stearic acid (6.42%), arachidic acid (0.42%), behenic acid (0.13%), lignoceric acid (0.09%), palmitoleic acid(0.77%), oleic acid (39.43%), linoleic acid (35.04%), linolenic acid (0.38%) and erucic acid (0.45%). The total saturated fatty acids of 23.93% and the total unsaturated fatty acids of 76.07% of the oil is an indication that the oil may not congeal at ordinary room temperature. This study showed that the oil can be refined to improve the quality parameters.
Fatty acid, Composition, Akee, Oil, Physicochemical, Extraction
Akee (Blighia sapida, L,; Family: Sapindaceaea) is a perennial herbaceous plant to Jamaica in the 10th century mainly as a food for residents. It gained scientific recognition in 1793 when Captain William Bligh introduced it to England in honor of whom it was named ‘Blighia sapida’ [1] . It is an evergreen tree, which grows to a height of between 7 and 25m. Akee trees grow well in Jamaica with little cultural attention and cultivated mainly in the parishes of Clarendon and St. Elizabeth. It produces good yield of 7.5 to 10cm long, lipid-bearing fruits all the year round, with two peak fruiting season of January to March and June to August [1] . Akee is widely consumed in Jamaica as part of the national dish. It is also popular among the Jamaican in the United State and Canada, countries where it was previously prohibited [2] .The production of Akee apple varies from year to year and probably governed by prevailing climatic conditions. [3, 4] reported that a larger numbers of fats can be extracted in Akee arils which contains many important nutrients, especially fatty acids. Linoleic, palmitic and stearic are the primary fatty acids found in the fruit [5].It was reported in the literature that Akee oil makes important contribution to the diets of many Jamaicans[1][3] .The Akee must be allowed to open fully or at least partly it is detached from tree. When it is ‘’yawned” the seeds are discarded and the arils, while still fresh and firm are best parboiled in salted water or milk and then lightly fried in butter. Then they are readily delicious. In Jamaica, they are often cooked with fish, onions and tomatoes. After parboiling, they are added to as stew of beef, salt-pork and scallions, thyme and other seasonings. Sometimes they are curried and eaten with rice. They are served, not only at home, but also in hotel dining rooms and other restaurants. In Africa, they are eaten raw or in soup, or after frying in oil [6]. The dried seeds, fruit bark and leaves are used medicinally. In Brazil, the seed aqueous extract has been administered to expel parasites. The treatment is followed by a saline or oily purative. Cubans blend the ripe arils with sugar and give the mixture as a febrifuge and as a treatment of dysentery. On the Ivory Coast, the bark is mixed with pungent species in an ointment applied to relieve pain. The crushed new foliage is applied on the forehead to relieve severe headache. The juice is employed as eye drops in ophthalmic and conjunctivitis. Various preparations are made for treatment of epilepsy and yellow fever [6] .Although, literature shows some chemical and biological studies on Akeemost especially in Jamaica [5,7] .Information on the quality parameters of oil extracted from Akee arils in Africa and mostly in Nigeria have not been fully investigated and documented. Hence this research work was aimed at investigating the physicochemical properties and fatty acid composition of oil extracted from Akee apple seeds collected from akee trees in Owo, Ondo State of Nigeria.
Collection of Akee Apple Seeds
Matured open seeds of akee apple were collected from nearby farms from Rufus Giwa Polytechnic, Owo, ondo State Nigeria.
Extraction of oil from the Seeds
The whole seeds were sundried for 7 days to aid the cracking of the shell.The cracked seeds were milled and washed with hexane.It was shaken vigorously for 30 minutes after which the solution was filtered. The filtrate was heated for 2 hours in order to allow the total escape of hexane. The extracted oil was then cooled in the desiccator.
Determination of Physicochemical Qualities of the Oil
The physicochemical qualities of the oil such as the specific gravity, smoke point, flash point, fire point, moisture content, melting point, peroxide values, iodine value, acid value, free fatty acid and saponification values were determined according to the methods of [8] .
Determination of fatty acid composition
The fatty acid composition was determined according to the method of [9] .
The result of the physical properties of oil extracted from Akee apple arils were shown in Table 1. The yield of oil produced was 15.26%. This value is low and may not make oil from akee apple to be viable industrially. The yield of the oil obtained in this study was low to what was obtained from Akee apple obtained from Supare-Akoko of Ondo State as reported by [3] .The low yield of oil from untreated seeds has been reported to be probably due to the presence of moisture and undenatured protein molecule [10] as they are known to reduce efficiency of oil extraction[10] .The Akee apple oil had a specific gravity of 0.85. The value compared well with what was reported in the literature [3]. The low value could be because of the high Saponification and Iodine values of the sample since density of an oil increase with release in Saponification value (mol weight), Iodine value (unsaturated), temperature, free fatty acid and water content [11]. The moisture content of 0.48% obtained though high is not appreciably far from the recommended standard of 0.2% for fresh oils as specified by [10]. Low value of moisture mean there will not be a great loss of mass if the oil is subjected to further processing or refining. Moreover, the colour unit of the extracted oil (14units) was higher than the recommended value of 9units [12]. This may be due to the fact that the oil did not undergo any processing of refining.
Table 1: Physical Properties of Akee Apple oil
Fats are heterogeneous mixtures which do not have a sharp melting point [13]. Melting point is the temperature at which melting of a fat starts ( The Akee apple oil had melting point of 150C and remained liquid at room temperature. The result of the smoke test (1350C) showed that the oil is suitable for frying [14]. The flash point of the Akee oil was found to be 1700C, which is lower than the flash point range of 2650C-2300C in most oils [15]. .A temperature (flash, smoke and fire points) usually vary with the amount of free fatty acids present in oil and decreasing with increasing free fatty acids [16]. These values also showed that the oil has combustion characteristics [16].
The chemical properties of oil extracted from akee apple arils are shown in Table 2. Freshly extracted oil has the peroxide value less than 10Meq/kg and that the rancid taste often begins to be noticed when the peroxide value is between 20 and 40Meq/kg, which indicates that the oil is of high quality and not easily prone to rancidity. This value is lower than the maximum 15Meq/kg for cold pressed and Virgin oils [17] showing that the oil will be good for consumption. Similarly, the Iodine value of 22.84wijs obtained is low compared to other oil such as from almond seed [18] Tiger nut [19] . Nutsedge oil and Shea fat [20] .Based on the Iodine value which is below 100wijs, the oil could be classified as non-drying oil and not easily prone to rancidity [18].
Table 2: Chemical Properties of Akee Apple oil
An acid value of 57.22mgKOH/g was obtained for the Akee apple oil. High acid value has been reported to be due to lipase action on oils prior to processing and high moisture content. Result from this study showed that the oil would need to be refined, as this will improve the quality of the oil as it is done in other vegetable oils [18]. Also, a high free fatty acid value of 28.61% oleic was obtained. [21] reported that high value of free fatty acids in oil gives rise to off-flavours and odours, increased susceptibility to rancidity and loss in the yield of the oil during refining when free fatty acids are removed.The saponification value (SV) of 245.43mgKOH/g obtained in this study was higher than the recommended range (188-198mgKOH/g) for edible oils [22] . This is an indication that the oil is composed of short chain fatty acids since the SV is higher than 200. [22]reported that oils with SV above 200 contain short chain fatty acids (low molecule weight fatty acid). This was further proved by the fact that the oil remained liquid at room temperature. Short chain fatty acids are known for their quick supply of dietary energy especially under emergency conditions [23] and are usually used as sources of energy where there is difficulty in the digestion of long chain fatty acids.
Results from this study showed ( table 3) that oil from akee apple contains 76.07% of unsaturated fatty acids of which 39.43% is oleic acid (C18:1), 35.04% Linoleic acid (C18:2), 0.77% Palmitoleic acid (C16:1) and 0.45% Erucic (C22:1) while the saturated fraction of 23.93% is predominantly Palmitic acid (C16:0) with 16.14% and stearic acid (C18:0) constituting only 6.42%, Margaric acid (C17:0), Myristic acid (C14:0), Arachidic acid (C20:0), Behenic acid (C22:0) and Lignoceric acid (C24:0) were present only in almost undetectable amount of 0.36%, 0.28%, 0.24%, 0.13% and 0.09% respectively. However, Caprytic acid (C8:0), Capric acid (C10:0) and lauric acid (C12:0) were undetectable.Linoleic and Linolenic acids are the most important essential fatty acids required for growth, physiological functions and body maintenance [24] .Stearic acid has been reported to lower blood cholesterol [25]. Since the saturated fatty acids have the lowest percentage (23.93%): it implies that oil may not congeal at ordinary temperature. It is however reported that saturated fatty acids plays an important role in the structure of tissue.
Table 3: Fatty acid composition of Akee Apple oil
The akee apple oil studied in this work shows the presence of great physicochemical values and quality fatty acid composition. This study showed that the oil can be refined to improve the quality parameters as done in vegetable oils to increase its consumption tendency.