Mycotoxins

Due diligence checking for mycotoxins

The UK Malting Industry is committed to ensuring that its products conform to the highest quality and safety standards.  It has therefore been working for many years to reduce levels of contaminants, which are sometimes unavoidable in agricultural crops, to levels which are as low as possible.  In addition, the sector takes the initiative to monitor for contaminants which may become a problem, or which may enter legislative control from UK or European law.

Mycotoxins are contaminants which can occur in cereal grains as a result of mould infection.  This can occur both in the growing crop (field fungi) and during grain storage (storage mould).  There are many different mycotoxins.  In the UK, the Malting Industry has developed systems to safeguard its raw materials and its products against mould infections and mycotoxin production.  Only the highest quality barley is selected.  Harvested grain is dried to around 12% moisture for long term storage.  This is too dry to allow most moulds to flourish.  Best practice guidelines have been developed for drying and storing malting barley, in conjunction with the UK's HGCA Grain Storage Guide (Third Edition 2011).
 

Member companies of the MAGB collaborate to survey each year’s barley crop according to a current assessment of the risk posed by various contaminants. This survey, internal to the sector, is subsequently published on the MAGB website. Taken with the food safety monitoring survey conducted by the HGCA in co-operation with maltsters, a comprehensive picture is gained of the prevalence of mycotoxins in the UK malting barley crop. Trends can be observed from year to year, to assist in building the bigger picture and to modify future risk assessments. These surveys show that levels of mycotoxins in UK malts are very low – but vigilance remains key to ensure that the situation remains this way.

Aflatoxins

In the EU there are legal limits of 4µg/kg for total aflatoxins and 2µg/kg for aflatoxin B1 in cereals.  However, the moulds which produce aflatoxins grow best in conditions which are warmer than those generally encountered in the UK, thus aflatoxins are rarely found in cereals grown in the UK.  The MAGB has monitored levels of aflatoxins in malting barleys from successive harvests, and the levels found have always been well below these legal limits. No samples contained detectable B1.  Most samples contained either no detectable aflatoxins or less than one tenth of the legal limit. (source: Campden BRI-Nutfield)

Ochratoxin A

The moulds which produce this mycotoxin do not infect growing barley in Europe.  They can develop on harvested grain, but only if it is stored in damp conditions, and particularly if the grain temperature is high.   The minimum moisture content to support fungal development was previously considered to be 18% moisture, but it is now thought to be just above 14.5% moisture. This is a significant change in understanding, and means that storage practices might have to change outside the UK.  In the UK malting barley is routinely dried to about 12% moisture before storage.  This is too dry to allow ochratoxin-producing moulds to flourish.  The legal limits for Ochratoxin A in cereals in the EU are 5µg/kg for raw grain and 3µg/kg for processed grain (which includes malt).

Malting barleys have been monitored for Ochratoxin A content for many years.  These surveys continue to show that most UK malting barleys contain no detectable Ochratoxin A.  Prompt checking of the crop is done as soon as possible after harvest each year.  The results below of 'due diligence' checking by MAGB each year show the OTA tests carried out on the barley crops from 2006 to 2010.

In addition to the tests for mycotoxin on barley at harvest, tests are also carried out on the barley later in the year, to check that no problems have arisen with the formation of storage fungi, and the resultant mycotoxins that can be produced from storage bad practices.   As an additional check, tests are also carried out on finished malts, which can be seen below.

Fusarium mycotoxins

Fusarium moulds are widespread on growing crops and normally do little damage to the plant.  However, under some conditions they can produce a number of toxins from the trichothecene group, including deoxynivalenol (DON), nivalenol (NIV), zearalenone (ZEA) and T-2 and HT-2.   Since March 2007, maximum limits for DON and Zearalenone in cereals have been operated in the EU.   For DON these are at 1250µg/kg in raw cereals and 750µg/kg for processed cereals (which includes malt); for Zearalenone these are 100µg/kg and 75µg/kg respectively.

It is anticipated that maximum limits will be established for T-2 and HT-2 in the near future – indeed the European Commission have stated an intent to legislate but so far have not done so although discussion is continuing.

The levels of Fusarium toxins in malt can be controlled by good farming practices producing good quality barley, then by grain inspection at intake from farm, by efficient drying and good storage conditions (for both malt and barley) and by attention to hygiene in the malting plant.

RESULTS OF DON TESTING

DON levels have been tested for MAGB over many years on finished malt, to ensure 'due diligence' as the data below shows for malts tested from 2006 to 2010 demonstrates:

RESULTS OF NIVALENOL TESTING

Results of tests on UK grown malting barley purchased by UK maltsters in crop years from 2006 to 2010 is shown below

Tests have also been carried out for NIV on UK malt made from UK malting barley for several years as part of the MAGB due diligence testing system, the results of which are shown below in chart form.

RESULTS OF ZEARALENONE TESTING

The test results for the due diligence cross checking for the presence of Zearalenone are shown below for barley then malt:

The results detailed above were carried out for MAGB by Campden BRI at Redhill, UK, as part of the annual HGCA funded work on the food safety of cereals in each crop year.

For a workbook showing all the results of MAGB mycotoxin survey work as part of the HGCA funded work on the food safety of cereals in each crop, including testing for OTA, DON, 3-AcDON, 15-AcDON, NIV, HT-2, T-2, Fusarenone-X, Neosolaniol, Diacetoxyscirpenol, ZEA , Citrinin and Cytochalasin CLICK HERE