Use of selected essential oils to control aflatoxin contaminated stored cashew and detection of aflatoxin biosynthesis gene.

Abeer R M Abd El-Aziz,Mohamed A Mahmoud,Monira R Al-Othman,Munirah F Al-Gahtani

doi:10.1155/2015/958192

Abeer R M Abd El-Aziz, Mohamed A Mahmoud + Show 2 more

Open Access

https://doi.org/10.1155/2015/958192

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Abstract

Aspergillus spp. associated with cashew from the regions of Riyadh, Dammam, and Abha were isolated and three different culture media were used to qualitatively measure aflatoxin production by Aspergillus via UV light (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. Five commercially essential oils (thyme, garlic, cinnamon, mint, and rosemary) were tested to determine their influence on growth and aflatoxin production in A. flavus and A. parasiticus by performing high-performance liquid chromatography (HPLC). 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. PCR was used with four sets of primer pairs for nor-1, omt-1, ver-1, and aflR genes, enclosed in the aflatoxin biosynthetic pathway. The interpretation of the results revealed that PCR is a rapid and sensitive method.

Highlights

Cashew nut (Anacardium occidentale L.) is characterized by the high percentage of carbohydrates and lipids which facilitates attacking them by moulds, Penicillium and Aspergillus [1]
Detection of Aflatoxins Produced by Aspergillus spp
The all tested essential oils appeared more effective on the growth at three tested doses compared to control; % inhibition of dry weight decreased with increasing doses of all treatments by essential oils

Summary

Introduction

Cashew nut (Anacardium occidentale L.) is characterized by the high percentage of carbohydrates and lipids which facilitates attacking them by moulds, Penicillium and Aspergillus [1]. The aflatoxins are a group of chemically similar toxic fungal metabolites (mycotoxins) produced by genus Aspergillus. The presence of Aspergillus in stored cashew nuts appears in deterioration, discolouration, and bad odour [6]. Synthetic chemicals are not used to manage mycotoxin production which cause harmful effects on consumers [7]. Recent trends toward natural product such as essential oil lead to safe and acceptable method. Many approaches investigated to manage aflatoxin production using essential oils [8,9,10,11,12]

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