MEKARN Conference 2010
A survey on the contamination of maize with aflatoxins, fumonisins and zearalenone was carried out in the Southeastern provinces and Central Highlands provinces in Vietnam, on 97 maize kernel samples. Four provinces were chosen for sampling maize: Dong Nai (22), Binh Phuoc (25), Dak Lak (30) and Dak Nong (20). Aflatoxin B1 (AFB1), B2 (AFB2), G1 (AFG1), G2 (AFG2), fumonisin B1 (FB1), fumonisin B2 (FB2) and zearalenone (ZEA) were detected by an HPLC method (Romer Labs, Singapore).
Fumonisins was the most common type of toxin found in all samples (67%), followed by aflatoxins (55.7%) and zearalenone (27.8%). The incidence of aflatoxin positive samples in the Southeastern provinces (61.7%) was higher than in the Central Highlands (50%), while fumonisins and zearalenone incidences were contrary. The level of fumonisin B1 in samples from the Central Highlands provinces (1757 ppb) was significantly different from that of Southeastern provinces (740 ppb) (P<0.05). Moreover, the mean value of AFB2 in the Highlands samples (20.7 ppb) tended to be higher than in the Southeastern provinces (10.5 ppb) (P=0.071). The co-occurrence of the three kinds of mycotoxin in the 4 provinces was very high, at 77.3, 80.0, 86.7 and 90.0%, respectively, in Dong Nai, Binh Phuoc, Dak Lak and Dak Nong. The incidence of AFB1 found in Binh Phuoc, Dong Nai, Dak Nong, Dak Lak was 72, 50, 50 and 50%, with mean levels of 135, 55.7, 124, 201 ppb respectively. AFB2, AFG1, AFG2 had lower incidences and mean values, particularly AFG2, which was not found in samples from Dong Nai and Dak Nong. FB1 incidences in Binh Phuoc, Dong Nai, Dak Nong and Dak Lak were 44, 68, 85 and 73%, respectively, with average concentrations of 642, 812, 1155 and 2223 ppb, respectively, and FB2 also had lower incidences and mean values. Furthermore, ZEA concentrations and percentages of positive samples were low in Binh Phuoc and Dong Nai (40, 62 ppb and 12 and 9%, respectively) and were higher in Dak Nong and Dak Lak (456 and 210 ppb and 40 and 47%, respectively). The incidence of positive samples with high concentrations of aflatoxins was about 70%, while fumonisins and zearalenone had more positive samples with low concentrations (90 and 63%, respectively).