Contamination of German malting barley and of malt-produced from it with the mycotoxins ochratoxin A and B

For ochratoxin A in foodstuffs, a maximum tolerated concentration of 3-5 mu g/kg has been suggested. Because of the widespread occurrence of this myco toxin, almost all food groups, including beer, would be affected. The prese nt study aimed at an assessment of the state of contamination by ochratoxin A (OTA) and its dechlorinated derivative, ochratoxin B (OTB), of malting b arley from the harvest in the wet year 1996 and of malt produced from this barley. It was expected that these data would reveal the general levels of contamination and the influence of storage conditions and the malting proce ss. Therefore, ochratoxin analyses were performed in samples obtained from 16 or 17 malting plants from Various parts of Germany; the samples included malting barley immediately after harvest (n = 89), after 5 months of stora ge (n = 99) as well as malts obtained from these barley lots (n = 94). The samples were extracted, purified by means of immunoaffinity columns and sub jected to HPLC with fluorescence detection. OTA was found in 7.1 %, 10.1 % and 11.7 % and OTB in 7.8 %, 4.0 % and 5.3 % of the 3 kinds of samples. The positive samples originated from only about one half of the malting plants. The concentrations in the whole collective of positive samples were in the range of 0.02-1.2 mu g OTA/kg and 0.02-0.6 4 mu g OTB/kg. In the subgroups, the median Values were: in fresh barley 0. 035 mu g OTA/kg and 0.036 mu g OTB/kg, in stored barley 0.1 mu g OTA/kg and 0.14 mu g OTB/kg and in malt 0.26 mu g OTA/kg and 0.04 mu g OTB/kg. Thus, the mycotoxin concentrations were clearly below the values proposed f or unprocessed cereals. The results show that ochratoxins are present at a base level in the freshly harvest barley. Storage and malting did not signi ficantly change the incidence or concentrations of the toxin. This indicate s that the storage conditions are satisfactory and that neither synthesis n or liberation of ochratoxin from a bound state occur during malting.