Seasonal dynamics of accumulation of mycotoxins in corn grain

Abstract

Introduction. Many Fusarium species that are common in the soil can produce a number of different mycotoxins, including deoxynivalenol (DON), nivalenol, T-2 and HT-2 toxins and some other toxins such as zearalenone and fumonisins B1 and B2. The hazard of these mycotoxins to animals and humans is linked to the ability, both individually and in different combinations, to cause intoxication by exhibiting synergistic effects. Therefore, it is envisaged to control the accumulation of mycotoxins in grains and their products in connection with the occurrence of a significant risk to the animal and human.

Objective. to analyze the seasonal dynamics of Fusarium mycotoxin accumulation in corn grain intended for food and technical needs and exports.

Methods. The research was based at the State Research Institute for Laboratory Diagnostics and Veterinary and Sanitary Expertise during 2014-2017. In order to determine the content of mycotoxins such as deoxynivalenol, T-2 toxin, zearalenone, 325 samples of corn grain, which were received in different seasons, were used.  Determination of mycotoxin content in corn grain samples was performed using Ridascreen® test kits (R-Biophаrm AG, Germany). Results of the analysis were automatically calculated by the method of external standards using the RIDA®Soft software.

Results. The amount of T-2 toxin in corn grain in the fall was minimal and did not exceed the MRL for grain intended for food and technical use and for export. However, winter, spring, and summer showed an accumulation of this mycotoxin in the grain, which almost reached the MRL.

The amount of zearalenone in corn grain received for research at different seasons of the year was within the limits of the MPL. Analysis of corn grain samples taken during winter and spring showed that the zearalenone concentration in it was almost 1.5 - 2 times higher than in autumn.  Samples of corn grains that came to the laboratory during the summer contained significantly more zearalenone. This indicates the accumulation of this mycotoxin during storage.

The average amount of deoxynivalenol did not exceed the MRL (for food and technical needs and exports) for corn grain investigated in the autumn. The corn grain that was received in the winter, spring and summer study was contaminated with deoxynivalenol in most cases at the maximum permissible level. Certain batches of grain were unsuitable for use even for forage purposes.

Conducted analysis of the frequency of detection of mycotoxins in corn showed that the most common mycotoxins in corn were DON and T-2 toxin, less revealed zearalenone.

Discussion. Out of 325 samples of corn grain that came for research, 65 % were contaminated with mycotoxins, the level of which was within the permitted by MRL;  11,7% of the grain contained T-2 toxin, zearalenone and deoxynivalenol, and each exceeded the mentioned permitted level for grain intended for food and technical needs and exports,  and  6.5% of the samples contained deoxynivalenol and T-2 toxin at a level unacceptable even for forage purposes. 23 % of the  samples of corn grain were contaminated with two or more mycotoxins at the same time.

The lowest levels of T-2 toxin, zearalenol and deoxynivalenol were observed in corn grain during the autumn storage period. In winter, autumn and summer, the accumulation of T-2 toxin, DON, zearalenone was observed in corn grain.

Risk assessment should be carried out through continuous monitoring of mycotoxins in grains during cultivation, storage and processing of grain to prevent the increase of mycotoxins in grains during storage. This will allow for measures to reduce the accumulation of mycotoxins in the cultivation, storage and processing of grain. The development and use of highly sensitive screening and confirmatory methods will allow the detection of as few mycotoxins as mycotoxin content is unstable and may increase over time. The introduction of periodic control of raw materials at all stages of storage and processing of grain is necessary in the process of grain entering the food chain.