Production of patulin and cytochalasin E by Aspergillus clavatus during malting of barley and wheat

Production of patulin and cytochalasin E by four strains of Aspergillus clavatus during small-scale laboratory malting of barley at 16 and 25°C was investigated. Fungal biomass, measured as ergosterol, appeared to be greater at 25 than at 16°C, but marked differences were observed between the degree of colonization by the different strains. Patulin was detected in extracts by HPLC. Net production was greater at 16°C, but amounts were strain dependent. Except for one strain, cytochalasin E was detected only in barley malted at 25°C. In experiments with wheat inoculated with two A. clavatus strains, ergosterol levels in the green malts were generally greater than in corresponding barley malts. Patulin was again detected in all samples, with the equivalent of 22.4 mg/kg being detected in one sample at 16°C, but cytochalasin E was only found at 25°C, the highest level detected being 13.8 mg/kg. In samples of barley spiked with toxin and kilned at 80°C for 24 h, only about one-fifth of the amount of toxin recovered from corresponding unkilned controls was detected. It is indicated that differences in both contaminant strains and temperature in different maltings may account for disparities between symptoms reported for individual outbreaks of mycotoxicosis associated with malting by-products.