Studying natural contamination with mycotoxins is of great importance
since food components and storage conditions may interfere in
metabolite biosynthesis of contaminant fungi. As it has been previously
demonstrated in the literature, our results supported that no strict correlation
can be established between the capability of production of the
strain in vitro and its actual occurrence in the food (Pitt et al., 2000). In
the presentwork, even though AOH and AMEwere the toxinsmost frequently
produced by the isolates in DRYES medium, they were much
less prevalent in pepper fruits. On the contrary, TeA was produced in
vitro by a lower number of isolates, but more fruits were contaminated
with this toxin. When studying the relationship between the natural
contamination of peppers and the Alternaria strains isolated fromthe respective
fruits, similar discrepancies were observed. From 15 TeA-contaminated
pepper, non-TeA-producing Alternaria spp. were isolated. A
possible explanation for this is that the producer fungus was no longer
viable or cultivable, but the toxin remained in the fruit. On the other
hand, several fruits were infected with strains that could produce
alternariol in DRYES, but the toxin was not found in them. It appears
that some components of the food may interfere in the biosynthetic
pathway of alternariols, reducing their incidence. Interestingly,
Siciliano et al. (2015) observed that 80% of Alternaria isolates fromrocket
and cabbagewere able to produce at least onemycotoxin in vitro, but
the same isolates seemed to lose the ability to synthesize TeA when tested
in vivo, effect not observed with alternariols and other toxins. However,
it should be noticed that the analytical technique used for TeA in
the food matrix in thementioned work presented a much lower recovery
than that applied for in vitro detection. These results lead to the conclusion
that visible deterioration caused by Alternaria cannot necessarily
be associatedwith toxin accumulation in the foodmatrix, nor be used as
a quality control for toxin contamination. Furthermore, what implies a
higher risk for consumers is that the absence of fungal isolates cannot
guarantee the absence of the toxin in the food.