2.2.5. Gamma Irradiation

Gamma irradiation is a treatment that can be used to disinfect crops by reducing the number of fungi or by mitigating mycotoxins already produced by the fungi in these crops [64]. A gamma source, such as cobalt-60, must be used to generate very high-energy photons. These photons are capable of killing spoilage and pathogenic microorganisms by causing damage to their DNA. The free radicals and ions that occur after the interaction of

the energy with water molecules present naturally in food products or crops will attack microbial DNA [101,102].

The important role of water in the successful use of gamma irradiation was supported by a study that investigated the degradation rate of OTA in aqueous solution and different food products (wine, grape juice, and wheat flour). The sensitivity of OTA irradiated at 30.5 kGy reached the maximum in water solutions. It was also demonstrated that OTA is highly resistant to the same irradiation dose in solid matrices or dry foods [87].

Another study confirmed the use of gamma irradiation to inhibit *A. flavus* and *A. ochraceus* and reduce AF and OTA in maize. In this study, low doses of 6 kGy lead to the inhibition of mold growth. The reduction of the formed AFB1 by 40.1%, AFB2 by 33.3%, and OTA by 61.1% in maize required higher doses (20 kGy) [86]. A different gamma irradiation study was performed on sorghum and showed that the reduction of natural fungi in sorghum reached 90% at 3 kGy with maximum reduction rates of 59% for AFB1 and 32% for OTA realized at 10 kGy [88].
