Factors affecting patulin production by Penicillium expansum.

Patulin, a mycotoxin produced by Penicillium spp. during fruit spoilage, is a major concern with regard to human health because exposure can result in severe acute and chronic toxicity, including carcinogenic, mutagenic, and teratogenic effects. In this study, we investigated the effects of Penicillium expansum isolate, apple cultivar, storage temperature and time, and pH on the production of patulin. Patulin was analyzed by a previously developed micellar electrokinetic capillary electrophoresis method. P. expansum isolates originating from across Ontario produced widely differing levels of patulin, ranging from 0 to >6 mg/g by dry mycelial weight. The highest patulin levels were those for isolates displaying aggressive growth (characterized by rapidly increasing acidity) accompanied by profuse mycelial development. Distinct patterns in fungal growth rates and patulin production were evident among isolates grown in McIntosh, Empire, and Mutsu ciders. Extensive fungal growth and higher patulin levels (538 to 1,822 microg/ml on day 14) in apple ciders were associated with incubation at room temperature (25 degrees C), although potentially toxic patulin levels (75 to 396 microg/ml on day 24) were also found in refrigerated ciders (4 degrees C) inoculated with P. expansum.