Figs - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 453

Detection of mycotoxin-contaminated fruit
One of the approaches to reducing health risks from po-
tentially contaminated foods may be careful sorting and
discarding of all suspicious items. An easy way of de-
tecting aflatoxin-contaminated figs by their characteristic
bright greenish yellow (BGY) fluorescence was proposed
by Steiner et al. (1988). Removal of all BGY-fluorescent
fruit reduced the contamination level from 22.6 ppb to 0.3
ppb of aflatoxin B 1 . However, a more detailed study showed
that BGY fluorescence is just an indirect indication of pos-
sible aflatoxin presence and therefore is not very reliable
as some nonfluorescent figs did contain the toxin (Wenk
et al., 1994; Doster and Michailides, 1998). Nonetheless,
this method can help in reducing aflatoxin risks.
Other analytical approaches for revealing mycotoxin-
contaminated figs include thin-layer chromatography
(TLC) (Allen, 1974), high-performance liquid chromatog-
raphy (HPLC) (Baumann and Zimmerli, 1988; Sharman
et al., 1991), enzyme-linked immunosorbent assay (ELISA)
(Reichert et al., 1988) and other immunoassays (Bacigalupo
et al., 1994), polymerase chain reaction (PCR) (Farber et al.,
1997), affinity liquid chromatography (MacDonald et al.,
2003), and liquid chromatography-mass spectrometry (LC-
MS) (Senyuva et al., 2005).

ular toxigenic strains and thus reducing the aflatoxin con-
tamination in figs (Dostor et al., 1996).

Detoxification
Significant amount of research has been directed at finding
treatments to enhance aflatoxin degradation in contami-
nated figs. Encouraging results were achieved with treating
aflatoxin-tainted figs with sodium bisulfate or sulfur
dioxide in combination with heat, ultraviolet illumination,
hydrogen peroxide, or potassium sorbate (Icibal and
Altug, 1992; Elmaci and Altug, 1994). The most efficient
combinations resulted in reduction in total aflatoxin up
to 94%.

Monitoring aflatoxin contamination in dried figs
Aflatoxins are toxic secondary metabolites of fungi namely
of Aspergillus flavus and Aspergillus parasiticus. Among
products possessing risk for aflatoxin contamination, dried
fig fruit became a target species in 1980s. Pioneering re-
search showed a significant relationship between presence
of aflatoxins and BGY fluorescence on fig fruit under long
wave UV light. As major producer of dried fig, Turkey
faces problems in the world trade especially with the Eu-
ropean Union as the major market for Turkish figs and
because of the low allowable limits of 2 ppb for aflatoxin
B 1 and 4 ppb for total aflatoxins. Besides the official control
system, a monitoring system is established by the Aegean
Exporters Union. In Turkey, dried figs are screened under
UV lamps and figs with BGY fluorescence are removed to
lower aflatoxin levels. Each year, a committee determines
the average percentage of figs with BGY fluorescence, and
the exporters are required to deliver the contaminated figs
to be reimbursed for the discarded portion. The contami-
nated figs are collected in a warehouse and then destroyed
as hazardous waste.

Preventing contamination
Understanding the process of fruit infection by toxinogenic
Aspergillus species is necessary for developing contami-
nation preventing strategies. The experiments of Buchanan
et al. (1975) demonstrated that A. flavus- inoculated unripe
green figs were resistant to the fungal invasion and con-
tained almost no aflatoxin. Fungus development and toxin
accumulation started when the inoculated fruit reached
firm-ripe stage, reaching the highest level in sun-dried fruit.
The inoculation trials conducted by Boudra et al. (1994)
confirmed the critical role of the firm-ripe stage for the
fruit contamination. A range of fungicides (e.g., mancozeb,
benomyl, captan, prochloraz) were applied in orchard trials
to control the colonization of figs by Aspergillus to reduce
ensuing contamination with mycotoxins. At early stages
of production cycle (at budbreak), the fungicides were ap-
plied both on the tree and on the soil, while at later stages
(fruiting, ripening, and shriveling), they were used only on
the soil under the trees to eradicate the soilbome fungi.
These antifungal treatments effectively reduced fruit con-
tamination, bringing it below the tolerance limits (Tosun
and Delen, 1998). Attempts are being made to use atoxi-
genic Aspergillus strains (strains not producing toxins) as
biocontrol agents competing in the environment with reg-

Pests
The sun-dried figs' contact with soil and their prolonged ex-
posure to orchard environment favor not only Aspergillus
infection but also fruit infestation with insect pests. One
of the major pests found in the figs is dried-fruit beetle
( Carpophilus hemipterus ), which readily penetrates fallen
overripe fruit but is not attracted to undamaged healthy
figs or to fruit that is very dry or far advanced in de-
cay. However, larvae that begin growth in overripe figs
may continue their development after the fruit is fairly dry
(Simmons and Nelson, 1975). Erakay and Ozar (1979) ob-
served rather high Carpophilus infestation of attached ripe