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Ethnobotanical
Leaflets 14: 559-69. 2010. Antioxidative
Potentials of Banana and Plantain Peel Extracts on Crude Palm Oil 1*Arawande Jacob Olalekan and 2Komolafe
Eniayo Ayodeji 1Department of
Science Lab. Technology, Rufus Giwa Polytechnic PMB 1019, E-mail: joawande1@yahoo.com 2Department of
Food Science and Technology, Rufus Giwa Polytechnic PMB 1019, E-mail: komodeji@yahoo.com Issued Abstract Crude
palm oil was obtained from a local palm oil producer at Iyere, Owo, Key
words: Crude palm oil, Banana and Plantain peel extracts,
Solvents, Yield, Antioxidant activity. Introduction Crude
palm oil is edible oil obtained from African oil palm (Elaeis guineensis). It has been long recognized in West African
countries, and among West African peoples it has long been in widespread use
as cooking oil (Wikipedia, 2007). European merchants trading with Palm
oil was previously the second most widely produced edible oil after soybean
oil, 28million metric tons were produced worldwide in 2004 (MOPS, 2005). The
oil contains high amount of beta-carotene which makes the oil reddish in
colour however the reddish colour turns white when the oil is boiled for few
minutes thereby destroying the carotenoids. It is one of the oils relatively
high in saturated fats and thus it is a semi solid at room temperature
because it contains almost equal proportion of saturated and unsaturated
fatty acids content. Palm
oil as an edible and cooking oil has been discovered to have an excellent
dietary energy source, very rich in vitamins A and E, stable in high
temperature (good for frying) and cheap vegetable oil due to the oil palm’s
high productivity (Koh, 2006).However, owing to its high content in saturated
fatty acids such as lauric acid, mystritic acid and palmitic acid which are
primary cholesterol-elevating fatty acids, palm oil promotes the risk of
coronary heart diseases such as hypertension, stroke, heart attach and other
cardiovascular diseases (Helen, 2007). In
Nigeria and some other African countries where palm oil is commonly found,
the oil merchants purchase it when it is relatively cheaper (that is during
its season) and store (hoard) for a period of six months or more and later
sold it when its price has gone up without considering the deterioration that
might have probably set in thereby posing more health risk to the consumers
of such oil (Arawande, 2008). Hence there arises the need to prevent oil
deterioration by adding antioxidant that will impede the oil rancidity. The
use of synthetic antioxidants such as Butylatedhydroxylanisole (BHT),
Butylatedhydroxyl toluene (BHT), Propylgallate (PG) and Citric acid to
prevent lipid oxidation have been established (Cuvelier et al., 1992; Ruger et al.,
2002; Ullah et al., 2003;
Khanahmadi and Janfeshan, 2006). But it has been discovered that some of
these antioxidants especially BHT and BHA are carcinogenic thereby they are
being discouraged in international market as food additives (Carrasquero et al., 1998). This leads to provoking
interest in seeking for safer means of natural antioxidants of plant origin
that will serve the same purpose of preventing oil rancidity (Tian and White
1994, Erol et al., 2004, Emmanuel
and Mudiakeoghene 2008). Banana
and Plantain peels are major agricultural wastes which have been used as
medicine, animal feeds, blacking of leathers, soap making, fillers in rubber
(Hephburn and Blow, 1971; Wikipedia, 2007). Owing to their colours (pigment)
when ripe, this suggests that their peels may probably contains antioxidants
which can be extracted with suitable solvents since the plants which contain
antioxidants are usually coloured. Therefore
the focus of this research is to obtain extracts from banana and plantain
peels using different solvents, to investigate the antioxidative effects of
highest solvent yield extract at varying concentrations on crude palm oil and
to compare their antioxidant activities with that of citric acid by monthly
monitoring their Free Fatty Acid (FFA), Acid Value (AV) and Peroxide Value
(PV) for a period of six months. Materials and Methods The
crude palm oil used for this work was purchased from a local palm oil
processor in Iyere, Owo, Preparation and
Extraction of Banana and Plantain Peels The
ripen peels were removed by hand and cut into smaller pieces for easy drying.
The dried peels were ground using electric blending machine and it was sieved
with 40mm mesh size. The powdery samples were packed into a black polyethene
bags labeled appropriately prior to extraction. Twenty
gram of each dried powdery samples were weighed into ten cleaned and dried
reagent bottles; and 200ml of each solvent (methanol, ethhylacetate, acetone,
acetic acid and chloroform) was separately added to each bottle and left for
72hours during which it was
intermittedly shaken on a shaking orbit machine. The mixture was filtered
through a 0.45μm Nylon membrane filter. The extracts were evaporated to
dryness under reduced pressure at 400C by a rotary evaporator.
Weight of extract obtained was used to calculate the percent yield of extract
in each solvent (Arawande and Abitogun, 2009). Addition of Additives
to Crude Palm Oil Acetic
acid extract of each peel at varying concentrations (0.02-0.10%) was added to
crude palm oil sample contained in transparent plastic containers and it was
thoroughly shaken for proper mixing. Crude palm oil containing 0.02% citric
acid and that which contain no additive (0%) was also set-up. Each container
was labeled appropriately. Chemical Analysis The
Free Fatty Acid (FFA), Acid Value (AV) and Peroxide Value (PV) of each oil
sample were determined monthly using standard method of analysis (AOCS, 1989)
for a period of six months. Results and Discussion The
percent yield of banana and plantain peel extract using different solvents is
depicted in Table 1. The amount of extract obtained increases as the polarity
of the solvent increases. Acetic acid yielded the highest extract in both
peels and the yield of methanol extracts was next to acetic acid. The percent
yield of extract in banana peel was higher than that of plantain peel in all
the solvents used .According to the rule of Thumb, natural antioxidants are
polar (phenolic) compounds and they are best extracted using polar solvents
(Amir et al., 2005). Ethylacetate,
acetone and chloroform yielded about 20-25% extract of the yield of acetic
acid in banana and plantain peels. The
Free Fatty Acid (FFA) of crude palm oil stored with varying concentration of
0.02%-0.10% acetic acid extract of banana and plantain peels was depicted in
Figures1 and 2. It was observed that the plots had similar trend with the
plot of free fatty acid of pistachio nut stored under various atmospheric and
temperature conditions as reported by Maskan and Karatas (1998). The FFA of
crude palm oil stored with varying concentration of banana and plantain peel
extracts were lower than the values obtained for oil sample that contained no
additive (%) in all the six month period of storage. It was obviously noticed
that the FFA of crude palm oil stored with 0.02%-0.10% plantain peel extract
was lower than that of the oil sample stored with 0.02% citric acid and 0.02%-0.10%
banana peel extract especially at the last three months of storage. Figures
3 and 4 respectively showed the Acid Value (AV) of crude palm oil stored with
varying concentration of 0.02%-0.10% of acetic acid extract of banana and
plantain peels. The trend observed above for FFA was also the same with that
of Acid Value in all the storage conditions only that the AV values were
higher than that of FFA. Ihekoronye and Ngoddy (1985) reported that the FFA
and AV of any lipid were both measure of hydrolytic rancidity and that the
lower their values, the slower was the rate of hydrolytic rancidity. Hence
crude palm oil stored with varying concentration of 0.02%-0.10% acetic acid
extract of banana and plantain peels were less prone to hydrolytic rancidity
even more than 0.02% citric acid. This showed that the extracts at varying
concentration demonstrated high antioxidant activity. However the antioxidant
activity of plantain peel extract was higher than that of banana peel extract
against hydrolytic rancidity of crude palm oil. The
Peroxide Value (PV) of crude palm oil stored with varying concentration of
acetic acid extracts of banana and plantain peels are shown in Figures 5 and
6 respectively. The plots obtained had similar trend with the plot of
peroxide value of pistachio nut and influence of garlic extract on the
oxidation process of edible oil (Maskan and Karatas 1998, Zalejiska-Fiolka
2001). It has been reported that peroxide value is a measure of oxidative
rancidity or stability of lipid and that high peroxide value of lipid is an
indication of high occurrence of oxidative rancidity (Gunstone and Norris
1983, Rossel 1994, Maskan and Karatas 1998, Amir et al., 2005). In
all the months of storage, crude palm oil stored with 0.02%-0.10% plantain peel
extract had lower values of PV than oil sample stored with 0.02% citric acid.
0.02%-0.06% banana peel extract also lowered the PV of oil sample than 0.02%
citric acid in all the storage months. Plantain peel extracts showed higher
antioxidant activity in crude palm oil sample than banana peel extracts,
although both extracts demonstrated higher antioxidant potential against
oxidative rancidity of crude palm oil sample than 0.02% citric acid expect at
0.08% and 0.10% banana peel extract. Considering the effect of concentration
of extracts, the antioxidant activity of plantain peel extract against
oxidative rancidity of crude palm oil decreases in the order of
0.04%›0.06%›0.02%›0.08%›0.10% while the antioxidant activity of banana peel
extract against oxidative rancidity of crude palm oil decreases in the order
of 0.04%›0.02%›0.06%›0.0%›.%. The optimal antioxidant activity of both peel
extracts was 0.04% while 0.08% and 0.10% of banana and plantain peel extract
gave the least antioxidant activity in crude palm oil. In
conclusion, plantain and banana peel extract was highest in acetic acid and
the acetic acid extracts of these peels had pronounce antioxidant
activity against both hydrolytic and oxidative rancidity of crude palm oil
stored in transparent plastic containers. Their antioxidant activity was much
higher at 0.04% than 0.02% citric acid. However further research can be
conducted using refined vegetable oils stored in tin and glass containers.
The antioxidant activity of water and methanol extracts of banana and
plantain peels can also be investigated at varying concentrations on crude
and refined edible oils over a period of twelve months. References Amir,
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Percent Yield of Banana and Plantain Peel Extract using different Solvents.
Mean of triplicate determinations± Standard
deviation
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