ИСТИНА

Citrinin (CTN), one of fungal secondary metabolites produced by Aspergillus and Pennicilium, may be detected in some cereal grains, such as corn, wheat, barley and rice. Also, CTN is detected in red yeast rice after its fermentation in the presence of Monascus purpureus used as a food colorant and flavor enhancer in the Orient. Since International Agency for Research on Cancer (IARC) classified CTN as a carcinogen (group 3), some countries have legally banned the production of foods with high content of CTN. So, the maximum level of CTN in red yeast rice, allowed in Taiwan and Japan, is 5.0 and 0.2 ppm, respectively. Toxicity of CTN stimulated a development of analytical methods of its detection. In this work we developed indirect ELISA for the determination of CTN in red rice. As a revealing conjugate we used gold nanoparticles (GNPs) with co-immobilized specific antibody (sAb) and horseradish peroxidase (HRP). Varying GNPs size and a molar ratio of sAb and HRP the conditions of synthesis of the triple conjugate were optimized. The activity of HRP was measured by the chemiluminescent method using luminol and 3-(10’-phenothiazinyl)propane-1-sulfonate as a substrate and enhancer, respectively. Detection limit (IC10), IC50 and working range (IC20 –IC80) for the proposed assay were 5.7, 44 and 12 – 171 ng/mL, respectively. This assay was applied to measure CNT content in red rice samples.