What is the toxin aflatoxin, in which crops it is found and how to fight it?
Aflatoxin, produced naturally by fungi of the Aspergillus group, is the most potent toxin in the world. There are several types of it, but the most common and dangerous for human health is type B1 aflatoxin, which can be produced in various agricultural crops. Most often, it is found in such crops as: nuts, walnuts, pistachios, almonds, corn and cotton.
The formation of aflatoxin depends on many factors, such as: temperature, substrate, soil surface reaction, humidity, drought, insect damage. For example, the toxin can be produced in nuts and grain crops due to improper storage, as the danger of mass spreading of fungi increases during “warming up”.
Aflatoxin in nut culture
For example, aflatoxin in hazelnuts can be distributed:
- from the soil during harvest under drought conditions, as fungi of the Aspergillus group are also present in the soil. If we do not harvest for a long time after the fruit fall, it is possible that the toxin from the soil will transfer to the fruit.
- In case of incorrect processing in the factory – when the fruit is not fully dried. It is recommended to dry the nuts to about 5.5-6% moisture.
- In the warehouse, where proper storage conditions are not observed, for example: temperature, humidity, ventilation, etc. At this time, there is a danger of “warming up” and the formation of fungi of the Aspergillus group.
It is recommended to harvest the hazelnuts at technical maturity, because at this time the fruit has dried to a certain level and the risks of its burning during drying in the factory or during storage are low, which prevents the spread of mold fungi that release aflatoxin in the warehouse.
Aflatoxin in maize crop
The spread of aflatoxins in corn mainly occurs when the plant is under stress for various reasons. It can be heat, insect damage and others. In corn culture, fungi of the Asperigus group, in addition to producing aflatoxin, are also pathogenic fungi. This disease is easily observed on taro and is manifested as light gray spots, obi.
According to the research institute of the University of Georgia, the necessary conditions for mushroom development are as follows:
factor | optimal | can develop |
temperature | 33℃ | 28-44℃ |
humidity of the air | 82% | 62-99% |
grain moisture | 18% | 13-20% |
In order to prevent the development of aflatoxin-producing fungi in corn , it is necessary to:
- weed control; (Chemical method – use of herbicides. Mechanical method – mowing)
- Assessment of the risks of spread of pests and diseases during vegetation;
- adjustment of the harvester so as not to damage the fruit;
- Harvest taro at no more than 14-15% moisture;
- timely and quality drying;
- removal and destruction of diseased and damaged taro from the warehouse;
- In the warehouse, we must control ventilation, humidity and temperature.
General recommendations for the prevention of aflatoxin formation
In order to avoid the development of aflatoxins in the products we produce, it is necessary to try as much as possible to avoid stress during the plant’s growing season. This can only be achieved by carrying out such agrotechnical measures as:
- use of healthy and certified seed material and seedlings;
- maximum cleaning of the plot from weeds; (Chemical method – use of herbicides. Mechanical method – mowing)
- We must control the risks of spreading various diseases and pests on the area throughout the year;
- Harvest only after making sure that the fruit is properly dried;
- control of certification of processing/drying plants;
- Plants/fruits damaged by pests are distinguished during drying or storage conditions;
- Store in a cool and dry place, protected from rain and pests.
Due to the excessive content of aflatoxin, a large part of the exported nuts in 2021 returned back to Georgia.
Compared to 2020, in 2021, a 25.8% increase in the export of nuts was recorded in Georgia, and our country took the eighth position in the ranking of the 10 largest export goods. However, it should be noted that Italy returned the imported nuts of the top 10 largest exporting companies to Georgia.
The reason was the excessive content of aflatoxin in Georgian nuts. Therefore, in terms of quality, the standards could not be met and 80% of the crop remained for sale.
The year 2021 turned out to be full of challenges for the market and the sector in general. To this day, the excess amount of aflatoxin in nuts remains one of the biggest problems, which can be easily overcome if the above rules are followed.
Aflatoxin-producing fungi: Aspergillus Flavus da Aspergillus Parasiticus.
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