Microbial contamination and mycotoxins from nuts in Riyadh, Saudi Arabia

Abstract

The occurrence of harmful aflatoxins from agricultural products varies with geographic location, farming practices and processing. To date, no data was reported from Saudi Arabia on mycotoxin content of nuts and edible seeds. Forty samples of edible nuts and dried seeds were randomly collected from different locations in Al-Riyadh, Saudi Arabia. Fungi were detected by seed-plate and dilutions plate method and were cultured on glucose-Czapek's agar, sucrose-Czapek's agar and starch yeast agar. Purified fungal isolates were identified morphologically. Mycotoxins were extractedusing chloroform and detected by thin layer chromatography. Bacterial analysis was done using total plate count method. There was a predominance of A. niger and A. flavus in all medium types. Aflatoxin B1 (8.5 μg mL-1) was detected in peanuts containing A flavus. Aflatoxin B1 (1.7 μg mL-1) and B2 (1.7 μg mL-1) was detected in sunflower seeds containing A terreus. T2 toxin (2.8 mg mL-1) was detected in pumpkinseeds containing Stachybotrys chartarum and DAS (2.4 μg mL-1) was detected in a salted peanut sample containing Trichthecium roseum. Four nut samples showed contamination with bacteria. Turkish pine seeds and American walnut had total plate counts of 12×10. Pakistani pine seeds and Iranian salted pistachio had TPC of 3×10. Listeria monocytogenes was isolated from American walnut samples. Government authorities for food safety consumption should continue to monitor and set appropriate guidelines and information initiatives for public knowledge on the safety of these agricultural products whole year round. © 2011 Academic Journals Inc.