The Problem

Mycotoxins

What are they?

Mouldy coffee beans

Mycotoxins¹ are naturally occurring chemical compounds produced by certain fungi that pose a threat to humans and animals when ingested. Fungi, like all heterotrophic organisms, need water and certain essential nutrients in order to live. Food crops represent a good source of nutrients for such moulds. As the moulds grow on these food commodities, they produce secondary metabolites, which include mycotoxins.

Each mycotoxin is produced by one or more very specific fungal species, and in some cases one species can form more than one mycotoxin (see table below). However, the prescence of a recognised toxin-producing fungus does not automatically imply the presence of the associated toxin as many variables are involved in mycotoxin formation. Conversely, the lack of visible mould is not a guarantee that the foodstuff is free from toxins as the mould may have already died, leaving the toxin intact.

The moulds and mycotoxins that are considered to be of major public health and economic significance worldwide are listed in the table below:

Mould species	Mycotoxins	Occurrence
Aspergillus parasiticus	Aflatoxins B1, B2, G1, G2	Maize (corn), groundnuts (peanuts), tree nuts, spices, dried fruit, crude vegetable oils, cottonseed and copra
Aspergillus flavus	Aflatoxins B1, B2
Fusarium sporotrichiodes	T-2 toxin	Cereals
Fusarium graminearum	Deoxynivalenol (DON)	Grains, especially wheat, barley, oats, rye and maize. Less often in rice and sorghum
Fusarium graminearum	Zearalenone	Maize, but also lower levels in rice, wheat, barley, malt and soybean
Fusarium moniliforme	Fumonisin B1	Maize
Penicillium verrucosum	Ochratoxin A (OTA)	Cereals, fresh grapes, dried vine fruit, wine, beer, coffee, cocoa
Aspergillus ochraceus	Ochratoxin A (OTA)
Penicillium expansum	Patulin	Fresh and processed fruit and vegetables (especially apples)

(see FAO, Food and Nutrition Papers 73, 'Manual on the application of the HACCP system in mycotoxin prevention and control', 2001)

¹ The term 'mycotoxin' combines the Greek word for fungus ('mykes') and the Latin word for poison ('toxicum'). Pitt (1996) defined mycotoxins as "...fungal metabolites which, when ingested, inhaled or absorbed through the skin cause lowered performance, sickness or death in man or animals, including birds".