Effect of Ultraviolet and Tungsten Rays on Aflatoxin B1 in Rice Flour

Aflatoxins are secondary metabolites produced by some species of Aspergillus fungus on agricultural products. They have great health, medical and economic significance due to mutagenic and carcinogenic effects on consumers. The purpose of this study is to compare ultraviolet and tungsten rays in reducing aflatoxin B1 in rice flour.

Contaminated rice flour with two concentrations of 50 and 100 ng/g of aflatoxin B1 that produced by Aspergillus flavus in the laboratory were illuminated at 5 times 10, 20, 30, 40 and 50 minutes, with two different distances of 7 and 14 cm from ultraviolet light source with wavelength 366 nm and tungsten 100 W. Aflatoxin content was measured using competitive ELISA in two replications. Aflatoxin levels were compared with control samples by SAS (Release 9.1, SAS Institute Inc., Cary, NC) software using Duncan test.

The results showed that maximum (67 and 68%) and minimum (14 and 18%) reduction of aflatoxin B1 occur after 50 and 10 minutes irradiation at 7 and 14 cm, by ultraviolet and tungsten light, respectively. The initial concentrations of Aflatoxin B1 did not affect the test, but reducing the distance to the source of light and increasing exposure time led to a further reduction of aflatoxin (P≤0.01).

Reducing the distance between rice flour and ultraviolet or tungsten ray source decreases aflatoxin further. On the other hand, the longer exposure to radiation, the more aflatoxin declines. The use of these rays can be considered in aflatoxin mitigation of food.