Cold and ambient deck storage prior to processing as a critical control point for patulin accumulation

Patulin, a mycotoxin produced primarily by Penicillium expansum, is currently of great concern because of its undesirable effects in human health. It has been proven that patulin can damage organs and tissues in animals and some studies revealed carcinogenic and teratogenic effects. Patulin is found mainly in low quality apples diverted to production of apple by-products. Apples from cold storage or recently harvested (usually ground harvested or low quality apples) are stored under ambient conditions (deck storage) until they are processed. The present assay studies the consequences of this type of storage in development of lesions and patulin accumulation. The assayed factors were the size of lesions when apples were taken out from cold storage, time the apples stayed at room temperature after cold storage (as a simulation of deck storage) and intraspecific differences between 2 isolates of P. expansum. A sublot of P. expansum inoculated apples was cold stored until lesions achieved concrete sizes. Then, apples were either transferred to a 20 degrees C storage room for 0 to 5 days or were analysed for patulin immediately. The rest of the apples were directly stored at 20 degrees C. Each treatment had three replicates. Increase of lesion size with time at 20 degrees C depended on initial lesion size after cold storage. Bigger lesions were always achieved in apples with bigger initial lesion size. Initial lesion size and time at 20 degrees C significantly influenced patulin accumulation. No significant amounts of patulin were found in apples with lesions up to 2 cm after cold storage. Patulin amounts significantly increased on the 2nd day at 20 degrees C day and remained constant until the 5th day. Patulin accumulation tended to be higher when initial lesions were bigger. The assay showed the influence of apple quality (measured as overall lesion size) after cold storage on patulin accumulation during deck storage, as well as the importance of duration of deck storage. Quality of apples entering the processing plant should be assessed in order to program deck storage and minimise patulin accumulation. Predictive models of patulin accumulation as a function of time at room temperature and apple quality should be a useful tool to elaborators.