الفهرس 
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Abstract
This study was carried out on 12 agro-industrial waste samples. They were as follows : potato peel, eggplant peel, prickly pear peel, pomegranate peel,
banana peel, mango peel, orange peel, peanut skin, pea pod, faba bean (broad
bean) hull, chickpea hull and guava leaves.
The main objectives of this study were:
1. to determine the total phenolic compounds, identify and the quantity of
the main phenolic compounds.
2. to study their activities as antioxidants and showing their capabilities to
prevent deterioration of sunflower oil heated at 60 oC for 24 days in a
continuative tool.
3. to evaluate the proximate chemical analyses of the agro-industrial wastes
under the study.
Data in this study revealed that:
A. Proximate chemical composition:
1. The chemical analyses of the waste samples showed that the peanut skin
had the highest value of dry matter 95% followed by chickpea hull 91.6%
then broad bean (Faba bean) hull 90% whereas the lowest one was found
in banana peel 9%.
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2. Pea pod was having the highest value of protein (15.1%) followed by
peanut skin (13.5%) then eggplant peel (11.6%) whilst guava leaves
contained the lowest value (2.2%) .
3. Peanut skin had (6.2%) fat followed by banana peel 4.8% then orange
peel 3% whereas potato peel had the lowest value (0.2%).
4. The ash in the waste samples under this study ranged between 2.25% to
16.3%. The highest value was determined in banana peel 16.3 % followed
by prickly pear peel then chickpea hull. The lowest ash content was
recorded for peanut skin 2.25%.
5. The crude fiber was differed significantly and ranged between 46% in
banana peel to 25.6% in potato peel.
6. The highest value of carbohydrates by difference was found in
pomegranate peel 62.9% followed by potato peel 60.6% till reached to the
lowest value in banana peel 27.4% .
B. Total phenolic compounds:
1. The phenolic compounds were extracted from waste samples under this
study using three solvents, methanol, ethanol and acetone; the study
revealed that the best solvent was methanol followed by ethanol then
acetone.
2. In methanolic extracts peanut skin had the highest total phenolic content
(78.36 mg GAE/g DW) followed by mango peel (77.22), pomegranate
peel (66.6), guava leaves (52.23), orange peel (50.53) and faba bean hull
(38.73), while, eggplant peel had the lowest total phenolic content (4.45
mg equivalent GAE /g DW).
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3. Ethanolic as well as acetonic extracts followed similar trend except that
the lowest amount of phenolics was recorded in pea pod, and chickpea
hull (4.28 and 5.05 mg equivalent GAE/g DW, respectively).
C. Identification and determination of phenolic compounds:
1. Twelve phenolic compounds were identified in most of the agroindustrial
waste samples.
2. The numbers and quantities of the phenolic compounds were varied in
the different waste samples under study.
3. Comparison among the wastes revealed that:
3.1- Homogentistic acid followed by catechin and Ferulic acid were
present in high concentrations, while vanillic acid followed by pcoumaric
were present in low concentrations in potato peel.
3.2 - Chlorogenic acid followed by Homogentistic and catechin were
present in high concentrations, while ferulic acid followed by pcoumaric
were present in low contents in eggplant peel.
3.3 - Homogentistic acid followed by salicylic and catechin were present
in high concentrations, while ferulic acid followed by p-coumaric
was present in low contents in prickly pear peel.
3.4 - Homogentistic acid followed by catechin and protocatechuic acid
were present in high concentrations, while vanillic acid followed by
p-coumaric were present in low contents in pomegranate peel.
3.5 - Catechin followed by ellagic acid and chlorogenic acid were
present in high concentrations, while Me – protocatechuic acid
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followed by caffeic acid were present in low contents in banana
peel .
3.6 - Chlorogenic acid followed by salicylic acid and catechin were
present in high concentrations , while ferulic acid followed by
gallic acid were present in low contents in mango peels .
3.7 - Ferulic acid followed by Me – protocatechuic acid and gallic acid
were present in high concentrations, while caffeic acid followed by
vanillic acid were present in low contents in orange peel.
3.8 - Catechin followed by protocatechuic acid and Me-protocatechuic
acid were present in high concentrations , while vanillic and pcoumaric
acids were present in low contents in pesnut hull .
3.9 - Ellagic acid followed by homogentisic acid and catechin were
present in high concentrations, while ferulic acid followed by pcoumaric
acid were present in low contents in pea pod.
3.10 - Salicyle acid followed by caffeic acid and ellagic acid were present
in high concentrations, while gallic acid followed by p-coummaric
were present in low contents in faba bean hull.
3.11 - Caffeic acid followed by Me –protocatechuic acid and catechin as
well as gallic acid were present in high concentrations, while
ferulic acid followed by p- coumaric acid as well as vanillic acid
were present in low contents in chickpea hull .
3.12 - Chlorogenic acid followed by catechin and salicylic acid were
present in high concentrations, while p-coumaric followed by
vanillic acid were present in low contents in guava leaves.
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D. Antioxidant activity:
1. The effect of waste sample methanol extracts as antioxidants was
estimated with DPPH. Free radical scavenging method.
2. The study showed that the highest value was recorded to guava leaves
(66.9%) followed by prickly pear peel (60.81%) then orange peel
(53.06%) whereas the lowest value was in eggplant peel 21.32%.
E. Oxidation stability of sunflower oil:
1. The oxidation stability of sunflower oil heated at 60oC for 3, 6, 11, 15, 18,
21 and 24 days continuously was studied by adding the different extracts
understudy as natural antioxidants at concentration of 200 ppm. BHA was
applied at the same concentration.
2. The following parameters were determined on time: Peroxide value, Panisidine,
TBA, FFA% and the Totox values.
3. There were gradually increases in the all parameters mentioned above.
But it was observed the positive effect of the waste samples as natural
antioxidants in reducing the deterioration of sunflower oil under storage
condtions.
4. The effect on PV
The inhibition % in PV for oil treated with wastes extract ranged
between 59-77%. The efficacy of waste extracts and BHA to decrease
PVs in oil could be arranging as follows:
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BHA > prickly pear peel ≥ guava leaves > faba bean hull ≥ orange peel >
mango peel ≥ pomegranate peel > chickpea hull > potato peel > peanut
skin > pea pod > banana peel > eggplant peel > control.
5. The effect on AV
The AV of oil with waste extracts was significantly different than
control sample (P <0.01). Significant differences were also observed
between oils with different wastes at almost all the intervals and the
stabilization effect was varied from 56-73% relative to control.
The effectiveness of waste extract as natural antioxidants compared
to synthetic one along with the control can be arranged in the following
descending order:
Guava leaves > prickly pear peel > BHA > orange peel > faba bean hull >
mango peel > pomegranate peel > chickpea hull ≥ potato peel > pea pod ≥
peanut skin > banana peel > eggplant peel > control
6. The effect on TBAVs
The TBAVs in oil with waste extracts were significantly lower than
control oil. Significant differences were observed among the oil with
waste samples at all intervals. The inhibition of TBA formation was
ranged between 46 to 81% relative to control. The efficacy of waste
extracts to reduce TBA can be arranged in the following descending
order:
Guava leaves > BHA > prickly pear peel > mango peel ≥ orange peel ≥
faba bean hull > pomegranate peel > chickpea hull > potato peel > banana
peel > pea pod > peanut skin > eggplant peel > control.
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7. The effect on FFA%
The efficacy of wastes and BHA to reduce FFA values could be
arranged in ascending order as follows:
BHA > guava leaves > orange peel > faba bean hull ≥ prickly pear peel >
mango peel > pomegranate peel > potato peel > chickpea hull > peanut
skin ≥ pea pod > banana peel > eggplant peel > control.
8. The effect on Totox value:
Oil mixed with waste extracts and BHA reduced significantly totox
value than control. Totox values of oil mixed with prickly pear peel
extract followed by guava leaves extract were closet to oil with BHA. The
efficiency of waste extract and BHA to reduce totox value could be
arranged ascendingly as follows:
BHA ≥ prickly pear peel ≥ guava leaves > faba bean hull > orange peel >
mango peel > pomegranate peel > chick pea hull > potato peel > peanut
skin > pea pod ≥ banana peel > eggplant peel > control.
In conclusions, from economic, environmental and health view points,
adding value to agro-industrial wastes is always appreciated.
Such wastes contain potentially valuable compounds that could be
isolated and used to make high-value foods. Based on the results of the current
study agro-industrial wastes could be used as a source of crude fiber and
phenolic compounds. Extracting the wastes with methanol produced extracts
with high phenolic contents which had fair to good antioxidant activity as
confirmed by DPPH assay.
The phenolic profiles were determined by HPLC and were found to be
complex mixtures of hydroxylcinnamic acids, hydroxylbenzoic acids, flavonoid
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and others. Variation in total phenolic content, DPPH radial scavenging activity
and individual compounds were noticed between waste samples. In this concern,
knowledge on total phenolic content, antioxidant activities and individual
phenolics of pea pod and chickepea hull could be the first attempted to report
here.
The addition of phenolic compound extracted from the wastes in this
study; as natural antioxidants; and BHA; as standard antioxidant; at 200 ppm
resulted in retardation of oxidative deterioration of sunflower oil during storage
under accelerated storage conditions.
Guava leaves and prickly peer phenolic extracts were comparable to BHA
in protection of sunflower oil against oxidative rancidity. Therefore, it could be
recommended them as well as other waste phenolic extracts but at higher
concentrations to use as sources of natural antioxidants to be used in oils and
fatty foods instead of BHA which might be had toxic and carcinogenic effects
on human health as reported in scientific literature.