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Potential mold growth, aflatoxin production, and antimycotic activity of selected natural spices and herbs
Abstract:
Ground spices and herbs are evaluated as substrates for mycelial growth, sporulation, and aflatoxin production. Three toxigenic strains of Aspergilli, A. flavus ATCC 15548, A. flavus NRRL 3251, and A. parasiticus NRRL 2999, were cultured on moist, commercially packaged herbs and spices. All substrates used were ground and included thyme, celery seed, oregano, cinnamon, ginger, caraway seed, clove, mustard, sesame seed, and rosemary leaves. Following inoculation of the natural materials in sterile bottles containing sterile water, the cultures were incubated 30 days at 23 +/- 4 degrees C. Not all strains of Aspergilli grew, sporulated, or produced toxins. There were definite strain differences and definite substrate differences for the variables evaluated. Sesame seed produced toxins B1, G1, and G2, with a mean of 167 ppm for 3 strains. A. flavus ATCC 15548 was the greatest overall toxin producer followed by A. parasiticus NRRL 2999 and A. flavus NRRL 3251. Ginger and rosemary leaves were also substantial producer-substrates. Mustard, caraway seed, and celery seed were judged as intermediate-producing substrates. Absolute antimycotic substrates were cinnamon and clove. Antiaflatoxigenic substrates were thyme and oregano. Mustard also may be antimycotic. Aflatoxins B1 and G1 were the more commonly found toxins.
Insights
Certain spices like sesame, ginger, and rosemary support aflatoxin production by Aspergillus fungi. Others, including cinnamon and clove, inhibit fungal growth, making them safe spices.
Area of Science:
- Food Microbiology
- Mycology
- Food Safety
Background:
- Spices and herbs are common food ingredients globally.
- Some Aspergillus species can produce harmful aflatoxins on various substrates.
- Understanding fungal growth and toxin production on spices is crucial for food safety.
Purpose of the Study:
- To evaluate ground spices and herbs as substrates for Aspergillus fungal growth.
- To assess mycelial growth, sporulation, and aflatoxin production by toxigenic Aspergillus strains.
- To identify spices that promote or inhibit fungal growth and aflatoxin contamination.
Main Methods:
- Three toxigenic Aspergillus strains (A. flavus ATCC 15548, A. flavus NRRL 3251, A. parasiticus NRRL 2999) were used.
- Cultures were grown on sterile, ground, commercially packaged spices and herbs for 30 days at 23°C.
- Mycelial growth, sporulation, and aflatoxin production (B1, G1, G2) were quantified.
Main Results:
- Significant differences in fungal growth and toxin production were observed among Aspergillus strains and spice substrates.
- Sesame seed, ginger, and rosemary leaves supported substantial aflatoxin production (up to 167 ppm on sesame seed).
- Cinnamon and clove demonstrated strong antimycotic properties, while thyme and oregano were antiaflatoxigenic.
Conclusions:
- Spice and herb substrates vary in their ability to support Aspergillus growth and aflatoxin production.
- Sesame, ginger, and rosemary pose a higher risk for aflatoxin contamination.
- Cinnamon, clove, thyme, and oregano can be considered safe or even inhibitory regarding aflatoxin contamination.