Surveillance of stored grain from the 1997 harvest in the United Kingdom for ochratoxin A

This survey examined 306 samples of farm-stored wheat, barley and oats as received at, or tested by, central grain depots in the UK. Samples were taken from lorries or from stored grain using the existing in-house procedures used for quality checking and examined for ochratoxin A using a fully validated analytical HPLC method with a detection limit of 0.1 microgram/kg. Ochratoxin A was detected in 21% of the samples examined, with barley more frequently contaminated than wheat. Mean concentrations of ochratoxin A found for all samples were 0.69 microgram/kg in barley, 0.29 microgram/kg in wheat and 0.15 microgram/kg in oats. The highest concentration found was 17.8 micrograms/kg in a barley feed although concentrations of 81 and 30 micrograms/kg were found in 'reject-grade' wheat samples whose results were excluded from the main survey. In summary, 2.7 and 0.3% of samples exceeded concentrations of 5 and 10 micrograms/kg respectively. There appeared to be significant relationships between ochratoxin A concentrations and moisture content, storage time and geographical area. Although conditions at harvest in 1997 were quite variable countrywide and often wet, results were similar to those found in earlier surveys carried out in the UK.