Abstract

Aspergillus spp. associated with pistachio from the regions of Riyadh, Dammam and Abha were isolated. The most frequently isolated Aspergillus spp. came from Dammam (56.1%), followed by Riyadh (47.6%), and the least frequently isolated species were from Abha (26.2%). Aspergillus flavus showed the highest prevalence in the investigated samples. Three different culture media were used to qualitatively measure aflatoxin production by Aspergillus under UV radiation (365 nm), which was expressed as positive or negative. The obtained data showed that six isolates of A. flavus and four isolates of A. parasiticus were positive for aflatoxin production, while all isolates of A. niger were negative. Extraction of aflatoxin from pistachio was then performed through high-performance liquid chromatography (HPLC). Commercially available essential oils from thyme, garlic, cinnamon, mint and rosemary were tested to determine their influence on growth and aflatoxin production in A. flavus and A. parasiticus. The results showed that the tested essential oils caused highly significant inhibition of fungal growth and aflatoxin production in A. flavus and A. parasiticus. The extent of the inhibition of fungal growth and aflatoxin production was dependent on the type and concentration of essential oils applied. The results indicate that cinnamon and thyme oils show strong antimicrobial potential.

Key words: Anti-aflatoxigenic, high-performance liquid chromatography (HPLC), essential oils, Aspergillus spp., pistachio.

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