Document Details
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Document Type |
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Article In Journal |
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Document Title |
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“Control of Aspergillus flavus in corn using natural materials” "مقاومة فطر الأسبرجلس فلافس فى الذرة باستخدام المواد الطبيعية" |
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Document Language |
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English |
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Abstract |
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Control of Aspergillus
flavus in corn using
natural materials
I would like to thank SfAM for
awarding me a President’s Fund grant to
attend the 9th European Conference on
Fungal Genetics held in Edinburgh, UK
on 5-8 April 2008.
I presented my paper on the
organisms that produce the mycotoxin,
aflatoxin, especially Aspergillus flavus.
This can infect important food and feed
crops, including corn, before, during
and after harvest. These fungi are
normal soil-borne inhabitants in our
environment, growing on both living and
decaying plant matter. Mycotoxins
include metabolic by-products produced
by a number of different fungi.
The importance of this study comes
from the prevalence of Aspergillus
flavus producing aflatoxin in corn,
wheat and barley crops. It is possible to
control contamination by preventing the
presence of the fungus (Aspergillus
flavus) and removing or affecting its
capability to produce the toxin. This
could be done by using natural materials
and may lead to the production of toxinfree
food and feed and increased safety
from a health point of view whilst
preserving grain food wealth.
I studied the control of Aspergillus
flavus using natural materials namely,
the essential oil marjoram (Origanum
majorana L.) and salt (sodium
chloride) and their effect on fungal
growth and the quantity of aflatoxin
production.
Effect of different concentrations
of marjoram (Origanum majorana
L.) essential oil and salt (sodium
chloride) on Aspergillus flavus:
One millilitre of Aspergillus flavus
containing 5.0x104cfu/ml was added to
100 grams of corn (sterilized in a 250
ml conical flask) and distributed without
the addition of marjoram or salt (control
sample). Also, one millilitre of the same
Aspergillus flavus with the addition of
different volumes of marjoram essential
oil (0.05, 0.1, 0.2, 0.3, 0.5 and 0.7 ml)
and one ml of the same Aspergillus
flavus with the addition of different
weight of salt (0.2, 0.4, 0.6, 1.0, 1.5 and
2.0 grams) were each added to 100
grams of sterilized corn (placed in a 250
ml sterilized conical flask) and mixed.
Sterilised distilled water was added to
raise the moisture content to 18% and
the mixture was shaken to make it
homogenous. These were stored at 25OC
for 21 days. Sampling to determine
Aspergillus flavus count and aflatoxin
concentration was made at intervals of 7
days until 21 days.
Adding 0.05 ml of marjoram essential
oil did not stop the growth of
Aspergillus flavus during storage and
up to 21 days, in inoculated corn. At the
beginning of storage Aspergillus flavus
count was 4.0x102 cfu/g and gradually
increased on day 21 to reach
1.5x103cfu/g.
The corresponding values in the
control sample were 4x102 Aspergillus
flavus count and 0 ppb aflatoxin
production at the beginning of storage
and 3.2x103 Aspergillus flavus and 150
ppb aflatoxin production at the end of
storage (21 days). This indicates that
the addition of 0.05 ml marjoram caused
a reduction of Aspergillus flavus count
of 62.5% at 21 days of storage. Raising
the level of marjoram to 0.1 ml inhibited
the growth of Aspergillus flavus and
aflatoxin production completely at 7
days until the end of storage. These
results are in agreement with those of
Paster et al., (1995) who reported that
the essential oil of marjoram has been
shown to inhibit mycelial growth and
aflatoxin production in Aspergillus
parasites and Aspergillus flavus —
both fungi which grow on stored grains.
This observation was noted clearly with
other higher marjoram levels.
It can be observed from the effect of
different salt concentrations on
A. flavus count during storage of
inoculated corn up to 21 days that the
control sample gave a gradual increase
in A. flavus number during storage from
0 to 21 days. It increased from 6x102
cfu/g to 5x103cfu/g at 0 and 21 days
storage period respectively. The
corresponding values, in inoculated corn
sample treated with 0.2 grams of salt
were 6x102cfu/g to 9x102cfu/g at the
same periods of storage. Although the
salt concentration (0.2 gram) was quite
low it still produced a slight effect
towards reducing the rate of growth of
A. flavus during storage. This trend
increased during storage, and was more
obvious when 0.4 grams of salt was
added. At this concentration the number
of A. flavus at 0, 7, 14 and 21 days
storage period became 6x102, 6.3x102,
6.6x102 and 7x102cfu/g, respectively. At
0.6% salt concentration growth
inhibition reached 83.3% and aflatoxin
production reached 50 ppb between 0
and 21 days while the control sample
reached 180 ppb during the same
period. Hence this concentration is not
suitable for controlling A. flavus growth
during storage.
Raising salt concentration to 1 gram
caused a complete inhibition of A.
flavus growth and aflatoxin production
during the whole experimented storage
periods (7, 14, and 21 days). The same
observation was noted when 1.5 and 2
grams of salt were used. Accordingly the
minimum inhibitory concentration to
prevent A. flavus growth in corn is 1
gram salt/100 gram corn and can be
successfully used in the storage of corn
up to 21 days. It is also suitable to
prevent aflatoxin production. Moreover
salt is traditionally used as a food, feed
ingredient and food preservative, so the
hazard would appear negligible.
It is possible to conclude that using
marjoram at concentration of 0.1 ml and
above per 100g corn at 18% moisture
inhibited the growth of Aspergillus
flavus completely at 7 days and up to
the end of storage also prevented
aflatoxin production.
Also it can be concluded that the
minimum inhibitory concentration to
prevent A. flavus growth in corn is 1
gram salt/100 gram corn. This
concentration can be successfully used
in the storage of corn up to 21 days. It
is also suitable to prevent aflatoxin
production. |
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ISSN |
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1479-2699 |
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Journal Name |
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Microbiologist |
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Volume |
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10 |
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Issue Number |
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3 |
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Publishing Year |
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1430 AH
2009 AD |
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Article Type |
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Article |
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Added Date |
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Saturday, September 10, 2011 |
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Researchers
| يوسف أحمد جبريل | Gibriel, Youssef Ahmed | Investigator | Master | yousef1000@yahoo.com |
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