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Trials towards reduction
of fungal growth and aflatoxin G1 production in Arabic
coffee using different additives
Fardos Bokhari* and Magda Mohammad Aly
Faculty of
Science, Biology Department, King Abd El-Aziz University, P.
O. Box 12161, Jeddah 21473, Saudi Arabia.
*Corresponding author. E-mail:
fmbokh@kau.edu.sa.
Accepted
19 February, 2009 |
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Thirty
samples of coffee beans were collected from different places
of Jeddah, Saudi Arabia to determine and identify fungal
population. Twenty six species belonging to 7 genera were
isolated using potato dextrose agar (PDA) and malt extract
agar (MEA) media at 28°C. The most prevalent genera were
Aspergillus and Penicillium. Aspergillus was
present in 73 and 100% of the samples but Penicillium
was present in 86.6 and 100% on the two mentioned media,
respectively. Also, Fusarium, Mucor, Rhizopus and
Alterneria were recovered in moderate incidences on the
two media. Out of the thirty samples of coffee beans
collected, thirteen were contaminated with mycotoxin
(43.3%). Mycotoxin profiles were also determined in these
samples. It was found that aflatoxin G1 (Afl G1) showed the
highest incidence rates of occurrence. It occurred in about
23.3% of all samples analyzed and in 54% of the mycotoxin
contaminated samples. The other toxins detected were
aflatoxins B1 (16.6%), B2 (10%), G2 (6.6%), ochratoxin
(10%), patulin (16.6%) and sterigmatocystin (6.6%). The
factors affecting the Afl G1 production by Aspergillus
flavus were studied. The results clarified that
addition of caffeine up to 1 g/l reduced the toxin synthesis
(Afl G1). The effect of some medicinal plants and spices
added singly or in combination to the malt extract, on
fungal growth and AflG1 production by A. flavus
was also studied. Cinnamon and cloves affected fungal
growth and mycotoxin production. No growth or toxins were
detected in the presence of the two plants. Saffron and
ginger did not affect fungal growth or prevented toxin
production by A. flavus. In conclusion, coffee beans
in Saudi Arabia are highly contaminated with toxigenic
fungi, specially, A. flavus, which was found in this
study to be the main producer of Afl G1. Medium,
temperature, vitamin C, caffeine and some medicinal plants
or spices which are used as a traditional additive in Saudi
Arabia may affect fungal growth or/and toxin production.
Key
words:
Aflatoxins, mycotoxin, Aspergillus, coffee beans,
secondary metabolites, medicinal plant, spices, additives. |
