Anti-Aflatoxin B1 monoclonal antibody, clone 7B20

Ultraviolet irradiation (UV) has been used as a non-thermal processing method for food disinfection. In disinfecting solid foods such as peanuts, UV irradiation could be shaded or attenuated with increased distance, resulting in non-uniform dosage distribution. An affordable, rapid, and feasible method for measuring and improving irradiance distribution, however, is unavailable for detoxifying peanuts. In this study, a method was developed for rapidly quantifying UV dosage distribution on peanuts in a UV disinfection process. The darkening of the UV indicator, AgCl, was linearly proportional to the UV dosage from 0 to 120 mJ/cm(2) delivered on peanuts. The uniformity of UV dosage distribution was described by measuring the color change of UV indicator at four points on two orthogonal axes of each peanut kernel. The UV indicator coated peanuts were then rotated in a customized cylindrical chamber at different speeds. A rotation speed with more uniform UV dosage distribution was determined and applied to an aflatoxin detoxification process. The results demonstrate that the UV uniformity was significantly improved when peanuts were rotated at 11 rpm in the cylindrical chamber. Furthermore, after irradiating with 2.3 mW/cm(2) UV-C for 2 h, the aflatoxin B1 degradation rate increased from 60.8 +/- 15.3 pmol g(-1) h(-1) to 75.0 +/- 10.9 pmol g(-1) h(-1) in the peanuts rotated at 11 rpm, compared to those that were not rotated.

In the biosynthesis of aflatoxin,verA,ver-1,ordB, andhypAgenes of the aflatoxin gene cluster are involved in the pathway from versicolorin A (VA) to demethylsterigmatocystin (DMST). We herein isolated each disruptant of these four genes to determine their functions in more detail. Disruptants ofver-1,ordB, andhypAgenes commonly accumulated VA in their mycelia. In contrast, theverAgene disruptant accumulated a novel yellow fluorescent substance (which we named HAMA) in the mycelia as well as culture medium. Feeding HAMA to the other disruptants commonly caused the production of aflatoxins B-1(AFB(1)) and G(1)(AFG(1)). These results indicate that HAMA pigment is a novel aflatoxin precursor which is involved at a certain step after those ofver-1,ordB, andhypAgenes between VA and DMST. HAMA was found to be an unstable substance to easily convert to DMST and sterigmatin. A liquid chromatography-mass spectrometry (LC-MS) analysis showed that the molecular mass of HAMA was 374, and HAMA gave two close major peaks in the LC chromatogram in some LC conditions. We suggest that these peaks correspond to the two conformers of HAMA; one of them would be selectively bound on the substrate binding site of VerA enzyme and then converted to DMST. VerA enzyme may work as a key enzyme in the creation of the xanthone structure of DMST from HAMA.