Mycotoxins – What Are They?
There are a vast number of known species of mould throughout the world. Mycotoxins are a group of toxic secondary chemical metabolites of certain species of fungus. Under favourable conditions of temperature and humidity, these fungi grow on certain foods and feeds, resulting in the production of Mycotoxins. Mycotoxins can occur both in temperate and tropical parts of the world, depending on the species of fungi and can affect agricultural products during growth, storage or transport.
Mycotoxins are of concern to humans because of the wide range of toxic effects they pose. They are toxic at very low levels (ppb) and are known to be carcinogenic as well as genotoxic and can cause damage to the immune system and vital organs such as the liver (hepatoxic) and kidneys (nephrotoxic).
Unfortunately Mycotoxins are incredibly robust and can survive even after high temperature production processes such as cooking. Control of growth of the fungi from which the toxins are formed is very difficult in practice due to the many variables involved; such as climatic exposure, crop stress and diverse agricultural practices.
Mould growth and subsequent toxin formation tends to occur in ‘hot spots’ and is gives rise to heterogeneous contamination of the commodity and Mycotoxins may be present in a foodstuff even when visible mould is not seen. Growth of the mould species is generally a problem in the tropics and sub-tropics.Therefore products, such as spices, imported from third world countries present major sources of exposure.
It is worth remembering that Human exposure is not always from direct consumption of contaminated commodities but also from eating animal products that have themselves been fed on contaminated feeds.
Mycotoxins of Concern to Spices
I.) Aflatoxin – B1, B2, G1, G2
In 1960, Britain’s poultry industry was decimated in a matter of months by an apparently new disease. An investigation into the early outbreaks traced the source of the contamination to Brazilian peanut meal used as feed, which proved to be highly toxic when fed to poultry. The investigation eventually concluded the toxicity was of fungal origin (Aspergillus flavus) and the toxin was given the name Aflatoxin by virtue of its origin (A. flavis > Afla)
The aflatoxins are a group of structurally related toxic metabolites produced by at least four species of Aspergillus, A. flavus, A. parasiticus, A. nominus and A. niger and can occur in a wide range of important raw food commodities, including cereals, nuts, spices, figs and dried fruit.
There are 6 Aflatoxins of concern, 4 of which (B1, B2, G1 and G2), occur in various foods and 2 of which (M1 and M2) are metabolites found in the milk of lactating animals which have eaten Aflatoxin contaminated feed. Aflatoxin B1 is the most common of these as well as being one of the most potent hepato-carcinogens known to man.
II.) Ochratoxin A
Ochratoxin A – or OTA as it is commonly abbreviated, is the most frequently occurring of a group of structurally related toxic compounds. OTA is typically produced by the mould species Aspergillus ochraceous and Penicillium verrucosum and is globally one of the biggest Mycotoxin contaminants of agricultural commodities and foodstuffs.
OTA is highly toxic being genotoxic, nephrotoxic and also a suspected carcinogen. It is also an immunosuppressant in many animals.
Regulations for Mycotoxins in Certain Spices
I.) Commission Regulation (EC) No 472/2002 identifies the following Spice products with regards to setting maximum limits for Aflatoxins (B1, B2, G1, G2):
a) Piper spp. (pepper – fruits thereof, including white and black)
b) Capsicum spp. (dried fruits thereof, whole or ground, including chillies, chilli powder, cayenne and paprika)
c) Zingiber officinale (ginger)
d) Curcuma longa (turmeric)
e) Myristica fragrans (nutmeg and mace)
The maximum level for each of the aforementioned spices is 5ppb Aflatoxin B1 and 10ppb Total Aflatoxin (B1, B2, G1, G2).
II.) At the time of writing, Regulation (EU) 105/2010 of 5 February 2010 is set to come into force later in the year. This is an amendment to Regulation (EC) No 1881/2006 setting maximum levels for certain contaminants. Regulation 105/2010 is set to introduce maximum levels for Ochratoxin A in certain foodstuffs – including spices.
The list of spices included in this new Regulation are the same as for Aflatoxin Regulation, as outlined above.
From 1st July 2010, a maximum limit of 30ppb shall be in effect (not applicable to product placed on the market before this date). This maximum limit will then be reduced to 15ppb from the 1st July 2012 (not applicable to product placed on the market prior to the subsequent date).
Analytical Methods and Controls
Currently the only reliable way to determine the Mycotoxin content of a product and therefore ensure compliance to Regulatory control measures is by sampling and analysis.
Samples should be representative of the batch as determined by Risk Assessment. The samples should then be analysed by a competent Laboratory preferably accredited to an appropriate standard.
Methods for Mycotoxin determination are typically by means of Chromatography, with High Performance Liquid Chromatography (HPLC) recognised as the more sensitive and reliable means of determining levels of Mycotoxins down to as low as 1ppb or lower. Thin Layer Chromatography (TLC) as well as Enzyme-Linked Immunosorbent Assay (ELISA) may also be employed.
© Gerald McDonald & Co Ltd. Author: Andy Bibby