Influence of essential oils on the growth of aspergillus flavus

Denisa Foltinová,Dana Tančinová,Miroslava Cí­Sarová

doi:10.5219/725

Denisa Foltinová, Dana Tančinová + Show 1 more

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https://doi.org/10.5219/725

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Abstract

This paper was focused on the determination of the inhibitory effect of selected essential oils on growth of ten isolates of Aspergillus flavus and their potential ability to produce mycotoxins in vitro by TLC method. The isolates were obtained from moldy bread of domestic origin. We followed the impact of five essential oils at 100% concentration - lemon, eucalyptus, oregano, sage and thyme. The effect of the essential oils we tested the gaseous diffusion method. We isolates grown on CYA (Czapek yeast extract agar), in the dark at 25 ±1 °C, 14 days. The diameter of colonies grown we continuously measured on the 3rd, 7th, 11th, and 14th day of cultivation. The results of the paper suggest that oregano and thyme essential oil had 100% inhibited the growth of all tested isolates of Aspergillus flavus. Lemon, eucalyptus and sage essential oil had not significant inhibitory effects on tested isolates Aspergillus flavus, but affected the growth of colonies throughout the cultivation. In addition to the inhibitory effect we witnessed the stimulative effect of lemon, eucalyptus and sage essential oil to some isolates. Together with the antifungal effect of essential oils, we monitored the ability of Aspergillus flavus isolates to produce mycotoxins - aflatoxin B1 (AFB1) and cyclopiazonic acid (CPA) in the presence of essential oils. Production mycotoxins we have seen in the last (14th) day of cultivation. Lemon and eucalyptus essential oil did not affect the production of mycotoxins. In the case of sage essential oil we were recorded cyclopiazonic acid production in three of the ten isolates from the all three repetitions, while neither isolate did not produced aflatoxin B1. The production of secondary metabolites was detected in all control samples. From the results we can say that oregano and thyme essential oil could be used as a natural preservative useful in the food industry.

Highlights

Microscopic filamentous fungi are significant destroyers of foodstuffs during storage, rendering them unfit for human consumption by retard their nutritive value and sometimes by producing mycotoxins (Kumar et al, 2007)
The results of the paper suggest that oregano and thyme essential oil had 100% inhibited the growth of all tested isolates of Aspergillus flavus
Together with the antifungal effect of essential oils, we monitored the ability of Aspergillus flavus isolates to produce mycotoxins – aflatoxin B1 (AFB1) and cyclopiazonic acid (CPA) in the presence of essential oils

Summary

Introduction

Microscopic filamentous fungi are significant destroyers of foodstuffs during storage, rendering them unfit for human consumption by retard their nutritive value and sometimes by producing mycotoxins (Kumar et al, 2007). The present and growth of fungi in food may cause spoilage and result in a reduction in quality and quantity (Baratta et al, 2008). Mold growth on bakery products during storage is a serious economic problem. Mold spoilage of bakery products has been the subject of many studies and a number of species have been implicated. The presence of toxinogenic fungi and mycotoxins in food and grains stored for long periods of time present a potential hazard to human and animal health. Improper storage conditions offer favorable environment for the growth of Aspergillus spp. Some species such as Aspergillus flavus can produce toxic secondary metabolites: like aflatoxins, ochratoxins, cyclopiazonic acid and they affect the food safety (Pardo et al, 2006)

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