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Mycotoxin production by molds isolated from 'Greek-style' black olives
1Department of Food Science and Technology, University of Nebraska, Lincoln 68583-0919.
Abstract:
Seventeen mold strains were isolated from 'Greek-style' black olives produced in Morocco. Eight of these isolates were identified as Aspergillus flavus, seven as Aspergillus petrakii, and two as Aspergillus ochraceus Wilhelm. The A. flavus strains were tested for production of aflatoxins B1, B2, G1, and G2; and A. ochraceus and A. petrakii strains were tested for production of ochratoxin, penicillic acid, patulin, and citrinin. The organisms were tested for mycotoxin production on five different substrates, including rice powder-corn steep agar, autoclaved rice, yeast-extract sucrose broth (YES), potato dextrose agar (PDA), and fresh olive paste. All strains of A. flavus produced aflatoxins on all substrates except olive paste and PDA. In PDA, only two strains produced Aflatoxin B1. Five A. ochraceus group isolates produced penicillic acid on one or more of the substrates, but only two out of the five produced penicillic acid on olive paste. None produced ochratoxin, patulin or citrinin. Quantities of aflatoxin B1 produced in rice ranged from 5 to 14 micrograms/g of rice, and of penicillic acid 15-32 micrograms/g of rice. In olive paste, the concentrations of penicillic acid were 11.4 and 30.2 micrograms/g. Biological toxicity of extracts of mold cultures was confirmed using chicken embryos and a microbiological test. Crude extracts of cultures were also tested for mutagenicity using the Salmonella mutagenicity (Ames) Test, and some gave positive mutagenic responses.
Insights
Mold contamination in Moroccan black olives was investigated. Aspergillus flavus produced aflatoxins, and Aspergillus ochraceus group produced penicillic acid, with some extracts showing mutagenic potential.
Area of Science:
- Food Microbiology
- Mycotoxicology
- Food Safety
Background:
- Mold contamination in food products poses significant health risks due to potential mycotoxin production.
- Greek-style black olives are a popular food item susceptible to microbial spoilage.
Purpose of the Study:
- To identify mold strains isolated from Moroccan black olives.
- To determine the mycotoxin production capabilities of these isolated mold strains.
- To assess the biological toxicity and mutagenicity of the produced mycotoxins.
Main Methods:
- Isolation and identification of mold strains from black olives.
- Cultivation of identified strains on various substrates to assess mycotoxin production (aflatoxins, ochratoxin, penicillic acid, patulin, citrinin).
- Quantification of mycotoxins and assessment of biological toxicity using chicken embryos and mutagenicity using the Ames Test.
Main Results:
- Seventeen mold strains were isolated, including Aspergillus flavus, Aspergillus petrakii, and Aspergillus ochraceus.
- All Aspergillus flavus strains produced aflatoxins on rice and yeast-extract sucrose broth but not on olive paste or potato dextrose agar.
- Five Aspergillus ochraceus group isolates produced penicillic acid, particularly on rice and olive paste, with some extracts demonstrating mutagenic activity.
Conclusions:
- Specific Aspergillus species found on Moroccan black olives are capable of producing harmful mycotoxins like aflatoxins and penicillic acid.
- The presence of these mycotoxins and their mutagenic potential highlight food safety concerns associated with contaminated olives.
- Further research is needed to develop effective control strategies against mycotoxin contamination in olive products.