Advances in Food Mycology

332 Monica Olsen et al.
The malting process can provide conditions favourable for the
growth of toxigenic fungi. Moist conditions during germination and
the initial stages of kilning are conducive to the growth of many fungi.
The extent of the development of mycotoxin producing fungi depends
largely on the initial contamination of the barley and on the vitality of
the organisms present. Moreover problems of mould growth during
malting have often been associated with elevated temperatures
(Flannigan, 1996). If P. verrucosum is present on barley it could proliferate
during malting and produce ochratoxin A especially at temperatures
near 20°C. However, no published data is available on the
formation of ochratoxin A during the malting process. The European
malting industry is now facing the new challenges caused by the established
legislation for maximum levels of ochratoxin A for raw cereal
grains and products derived from cereals.
There is little data available on the fate of ochratoxin A during the
brewing process. In experiments where ochratoxin A was added at various
stages during malting and brewing or malt containing high levels
of ochratoxin A was used, reduced amounts (13-32%) were always
found in beer (Chu et al., 1975; Nip et al., 1975; Baxter et al., 2001).
Losses to spent grains, uptake by the yeast and degradation, especially
during mashing, were the main reasons for reduced amounts recovered
in beer (Baxter et al.; 2001). Due to the thermo stable nature of
ochratoxin A, it is not destroyed to any significant extent during kilning
or wort boiling (Scott, 1996b; Baxter et al.; 2001). Surveys of
ochratoxin A in commercial beer are regularly carried out in several
countries. Very low concentrations of ochratoxin A have ever been
detected, the maximum levels ranging from 0.026 to 0.33 µg/l (Vanne
and Haikara, 2001). The final part of this project aimed at studying
the formation of ochratoxin A during malting and the subsequent fate
during the brewing process (WP11).
2. SUMMARY OF RESULTS FROM THE OTA
PREV PROJECT
2.1. Determination of the Critical Control Points
Investigation of grain samples has revealed that Penicillium verrucosum
is the main, if not the only, producer of ochratoxin A in
European cereals (Lund and Frisvad, 2003). It was concluded that
P. verrucosum infection was best detected on DYSG media after seven