Fungal contamination and mycotoxin-producing potential of dried beans

Abstract

A total of 604 samples of about 7 different types of beans was examined to determine their mycological profiles, and suitability for use as solid substrates for mycotoxin production. All of the samples were collected from bean jam makers in Tokyo by the official food examiners. Genera Penicillium and Aspergillus were predominant, and genus Wallemia was also found commonly in all types of beans. Mycotoxin-producing Aspergillus strains were isolated from 52 samples of beans, approximately 9% of the total. The highest incidence of toxigenic Aspergillus (14.1%) was found in kidney beans. Red beans and peas inoculated with Aspergillus ochraceus were found to produce about 7 to 8 times more toxin than was obtained in a liquid medium. and red beans inoculated with A. versicolor produced more toxin than was obtained in yeast extract sucrose broth. Green peas inoculated with Fusarium graminearum produced about 8 times more T-2 toxin than was obtained in 1% peptone containing Czapek solution under comparable culture conditions.