Patulin is a mycotoxin metabolite produced naturally by a range of fungal species growing on fruit especially:
- Penicillium
- Aspergillus
- Byssochlamys.
Penicillium expansum appears to be usually responsible for patulin in apples and a wide variety of other fruits including pears, peaches, banana, pineapple, apricot, cherries and grapes.
- Apples can be prone to particularly high levels of patulin.
- Normally patulin only occurs in fruit on which mould has grown although the spoilage may not be obvious.
- It is possible for the fungi to grow within the fruit, entering via insect or other damage (such as bruising) or in varieties with an open calyx to enter the core early during the fruits’ development.
- Often patulin is associated directly with storage diseases and there can be a higher risk in fruit from long term storage.