Natural co-occurrence of Fusarium toxins and aflatoxin B1 in corn for feed in north Vietnam.

ABSTRACT

Natural occurrence of Fusarium mycotoxins (trichothecenes and fumonisins) and aflatoxin B1 (AFB1) were surveyed in 32 corn samples, harvested in 1993 and randomly sampled in 1994 in several districts of Hanoi, Vietnam. Corn samples were first milled into fine powder, extracted with methanol-water (31) and the crude extracts obtained from the same samples were used for the simultaneous analysis of the trichothecenes such as nivalenol (NIV), deoxynivalenol (DON), and T-2 toxin (T-2) by gas chromatography/mass spectrometry (GC/NS); fumonisins B1 (FB1), B2 (FB2), and B3 (FB3) by high-performance liquid chromatography (HPLC) with a flourescence detector; and AFB1 by and ELISA kit based on a monoclonal antibody. The data revealed that 14, 8, 4, 3, and 2 out of 15 corn kernel samples were positive for AFB1, FB1, FB2, FB3, and NIV with the average levels being 28, 1, 101, 276, 232, and 858 ppb, respectively, and neither DON nor T-2 were detected. As for the other 17 samples of corn powder, 13, 15, 12, 10, 4 and 2 were positive for AFB1, FB1, FB2, FB3, DON, and NIV with the average being 30, 780, 289, 176, 3, 170, and 1,365 ppb, respectively, and T-2 was not detected. Although their positive rates and levels fell in the ranges reported elsewhere, it was found for the first time that the Fusarium toxins (NIV, DON, and fumonisins) and an Aspergillus toxin (AFB1) were naturally co-contaminated in selected samples of corn produced in north Vietnam.