Abstract
Aflatoxin B1 (AFB1) is a highly toxic and carcinogenic metabolite produced by Aspergillus species on food and agricultural commodities. Inhibitory effects of essential oils of Ageratum conyzoides (mentrasto) and Origanum vulgare (oregano) on the mycelial growth and aflatoxin B1 production by Aspergillus flavus have been studied previously in culture medium. The aim of this study was to evaluate aflatoxin B1 production by Aspergillus flavus in real food systems (corn and soybean) treated with Ageratum conyzoides (mentrasto) and Origanum vulgare (oregano) essential oils. Samples with 60 g of the grains were treated with different volumes of essential oils, 200, 100, 50, and 10 ÎŒL for oregano and 50, 30, 15, and 10 ÎŒL for mentrasto. Fungal growth was evaluated by disk diffusion method. Aflatoxin B1 production was evaluated inoculating suspensions of A. flavus containing 1.3 Ă 105 spores/mL in 60 g of grains (corn and soybeans) after adjusting the water activity at 0.94. Aflatoxin was quantified by photodensitometry. Fungal growth and aflatoxin production were inhibited by essential oils, but the mentrasto oil was more effective in soybeans than that of oregano. On the other hand, in corn samples, the oregano essential oil was more effective than that of mentrasto. Chemical compositions of the essential oils were also investigated. The GC/MS oils analysis showed that the main component of mentrasto essential oil is precocene I and of the main component of oregano essential oil is 4-terpineol. The results indicate that both essential oils can become an alternative for the control of aflatoxins in corn and soybeans.
Highlights
Loss of food commodities due to pest infestations is a major reason of food crisis in tropical countries (Prakash et al, 2013)
The results obtained by the disk diffusion method were 88.37 and 40.93% of inhibition of fungal growth for the A. conyzoides and O. vulgare essential oils respectively, when compared with control
The results of inhibition of fungal growth obtained allowed continuing our study, enabling us to verify the activity of these two essential oils in grains in order to envision their potential use as antifungal and/or antiaflatoxigenic
Summary
Loss of food commodities due to pest infestations is a major reason of food crisis in tropical countries (Prakash et al, 2013). Grains and cereals are exposed in the field and during the storage subjected to a wide variety of organisms. Among these organisms, fungi can cause a lot of damage to the grains during planting, harvesting, and storage (Sillker and Elliot, 1980). The grains serve as a suitable substrate for mold growth and mycotoxin production (Bryden, 2012). The presence of molds and mycotoxin in food commodities is a potential health threat to humans and livestock
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