2.2.4. UV-C Irradiation

UV light is another non-thermal treatment used as an alternative to thermal and chemical treatments to reduce the negative effects on the quality of treated foods and prevent the formation of residues and byproducts. UV light is classified into different bands according to the wavelength used. UV-C, which ranges from 200 to 280 nm, is commonly used because of its high efficiency against microorganisms, specifically at 250 and 260 nm [99].

The effect of UV-C irradiation on different types of rice was studied using UV irradiation at 254 nm for 1 and 3 h (moisture content of rice = 13%). The one-hour treatment was able to achieve a dose of 2.06 KJ cm−2, causing fungal decontamination and mycotoxin reduction in black and red rice without affecting the cooking and color characteristics. In contrast, the three-hour treatment increased the dose to 6.18 KJ/cm2 and increased the efficiency with a reduction of the total phenolic compounds. In brown rice, only the high dose achieved by the three-hour treatment was effective in reducing the fungal decontamination while causing undesirable browning of grains [73].

Low penetrability and the shadowing effect are two hurdles to the success of UV-C irradiation [100]. To overcome these problems and to increase the efficiency of UV irradiation, a customized rotational cylindrical chamber was established by Shen and Singh. In this study, the authors used a UV indicator applied to peanut kernels and treated with UV-C irradiation at 2.3 mW cm−<sup>2</sup> for 2 h with a continuous rotational movement at 11 rpm. The uniformity of the UV-C treatment was significantly improved when the reduction percentage of AFB1 was increased by 23.4% [85].

In another study, innovative vibrational decontamination equipment was designed for the decontamination of maize and peanut to increase the efficiency of this technology. UV-C irradiation was applied at a range of 1080 to 8370 mJ cm−2. After incubation for 10 days, the samples irradiated with 8370 mJ cm−<sup>2</sup> showed the lowest count of *A. flavus* in peanuts and maize. AFB1 reduction rates reached 43% and 51% for maize and peanut, respectively [84].
