Production of mycotoxins by Penicillium expansum inoculated into apples.

We investigated the production of mycotoxins in apple fruits inoculated with spores of 40 strains of apple blue mold, Penicillium expansum. Patulin and citrinin contents in the extracts from apples stored at 25 degrees C for 12 days after inoculation were determined by high-performance liquid chromatography (HPLC) analysis with UV and fluorescence detection. Patulin and citrinin were produced by 90% (36) and 80% (32) of the 40 strains, indicating that P. expansum is a consistent producer of these mycotoxins. The patulin content in the extracts was substantially higher than the citrinin content. Other mycotoxins whose production in pure culture has been reported were simultaneously detected with high-resolution liquid chromatography-mass spectrometry (LC-MS) analysis with the positive ion mode of electrospray ionization. Along with patulin and citrinin, expansolides A and B were identified based on the HPLC and LC-MS spectral data and detected in 88% (35) of the extracts. The results indicate that P. expansum is a consistent producer of expansolides A and B in rotten areas of apple fruits. The findings raise the possibility that products from decayed apples might contain expansolides A and B in addition to patulin and citrinin.