Advances in Food Mycology

334 Monica Olsen et al.
The probability, of ochratoxin A levels above the EC maximum
limit of 5 µg/kg at different concentration of P. verrucosum in the
grain, clearly increased when the levels of P. verrucosum were above
1000 colony forming units/gram (Lindblad et al., 2004). A mathematical
model was developed which describes the risk for condensation in
the headspace of a silo during storage of cereal grain. The model has
been used to identify the conditions which cause moistening of the
grain, and to develop control strategies to reduce this and the risk for
mould growth and ochratoxin A production (see www.slv.se/otaprev).
Essential oils, resveratrol and lactic acid bacteria (LAB) can control
growth and ochratoxin A production by both P. verrucosum and
A. ochraceus on grain (Ricelli et al., 2002; Cairns and Magan, 2003;
Fanelli et al., 2003). However, in small scale storage experiments and
experimental maltings, the inhibitory effect of the selected LAB strain
could not be shown clearly. Of twenty four essential oils tested the
most effective were found to be thyme, cinnamon leaf and clove bud.
2.3. Establishing Monitoring Systems
New diagnostic tools have become available that will provide the
means for rapid determination of ochratoxin A in cereals. This will
enable the effective implementation of the European legislation and
facilitate future internal control and scientific studies. Immunoassays
in ELISA format, sensitive enough to meet the EU legislation for
ochratoxin A, have been developed where hundreds of samples can be
analysed in a few hours. A lateral flow device (LFD) taking less than
five minutes to perform, which can be used on-site, has also been
developed (Danks et al., 2003, and unpublished results). These assays
are in the prototype stage but it is anticipated that a full validation and
comparison with CEN or the criteria mentioned in directive
2002/26/EC can be carried out in the near future. However, it has been
shown that these techniques are sensitive enough for the EU legislation
for ochratoxin A.
A number of genes involved in ochratoxin A biosynthesis have been
cloned, among them a polyketide synthase gene. PCR primer
pairs have been developed which appear to be highly specific for
A. ochraceus and P. verrucosum (O’Callaghan et al., 2003). The
primers may find use in the development of rapid identification
protocols for ochratoxigenic fungi.
Several advances have been made towards a molecularly imprinted
polymer specific for ochratoxin A and its integration into a solid phase
extraction (SPE) and sensor systems. Several polymers have been