Mycoflora and mycotoxins in adzuki and mung beans produced in Ontario, Canada

This is the first report on the detection of fumonisin B1 (FB1) in Fusarium-infected adzuki bean (Phaseolus angularis) and mung bean (Phaseolus aureus). The infected beans had either a mouldy appearance or a distinct discoloration. Seed coats of infected adzuki beans changed from dark red to light red and those of mung beans from green to dark or brownish green. Fusarium spp. isolated from mouldy and discoloured beans included F. avenaceum, F. culmorum, F. equiseti, F. graminearum, F. moniliforme, F. oxysporum, F. solani, F. sporotrichoides and a few unidentified species. Healthy beans without any apparent discoloration and diseased beans with discoloration and mouldy appearance were analysed for mycotoxins. Diacetoxyscripenol, deoxynivalenol and T-2 toxin (T-2) were not detected in either healthy or discoloured adzuki and mung bean samples by thin layer chromatography (TLC). FB1 was detected by TLC in discoloured adzuki and mung bean samples but not in the healthy samples. TLC results were confirmed by high performance liquid chromatography (HPLC). The quantification of FB1 by HPLC revealed that discoloured adzuki and mung bean samples contained 261 +/- 43.8, and 230 +/- 21.6 micrograms g-1 of FB1, respectively. This investigation emphasizes the need for more detailed research in dealing with possible mycotoxin contamination in various foodstuffs including legumes.