Monday, January 9, 2012

Moulds and mycotoxins

Pepin Heights Orchards and Minnesota Department of Agriculture have issued advice to consumers not to drink certain batches of Honeycrisp Apple Cider because of the presence of patulin at levels slightly above the 50 microgram per litre maximum level recommended by the World health Organisation. See:

Patulin is one of a host of compounds produced by moulds. These compounds are collectively referred to as "Mycotoxins".

We don't hear a lot about mycotoxins in the popular press - outbreaks of food borne illness are usually caused by Salmonella, Listeria, Campylobacter, or Escherichia coli, with several other bit players.

In fact, many fungi produce mycotoxins. One of my older textbooks devotes 66 pages of its 750 to these chemicals, some of which are very complex molecules. There is considerable discussion as to why moulds produce them, but they are probably just by-products of metabolism, though it has been suggested that in some cases, excretion of these "secondary metabolites" may confer some selective advantage, perhaps by inhibiting competitors in the soil.

Some of these chemicals can be very toxic - I well remember 1960 as the year when it was not possible to buy a turkey for Christmas in the UK, because thousands of young turkeys on poulry farms had died of the mysterious "Turkey X Disease". This was later shown to be caused by Aflatoxin present in peanut meal from Brazil as a result of growth of Aspergillus flavus mould. Intoxication of both humans and animals may be acute, but long term exposure may lead to cancer development.

Patulin in not regarded as particularly toxic to humans, but its presence in apple products is an indication of the quality of the apples used to make the products. There is some inconclusive evidence that patulin is genotoxic, i.e. it can damage the cell's genetic material. Pepin Heights has therefore been very responsible in their actions.

In America, fresh pressed apple juice is called Cider. In Europe, Cider, or Cidre is fermented apple juice. Patulin does not survive the fermentation process, so fermented cider is not likely to be contaminated with patulin.

Odd spot: a numbeer of mycotoxins are beneficial to humans, as they are in fact antibiotics - penicillin is just one example. Many drugs have also been made from mycotoxins.
St Anthony's Fire - ergot poisoning, has been known since about 600 BCE, but the pure ergotamine can be used to treat migraine.

For a much more complete, but readable, description of mycotoxins, go to:

1 comment:

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