Abstract:
The degree of postharvest losses of fruit and vegetables due to attack by
microorganisms worldwide is significant. In addition, the use of chemicals increases
consumer concerns regarding food safety. Recent studies indicate that exploitation of
natural compounds such as essential oils (EOs) may provide an alternative and
friendlier way for the preservation of fresh produce. In this research project the efficacy
of Origanum dictamnus L. essential oils (EOs) (a medicinal-aromatic plant of Crete) for
the control of B. cinerea, a common postharvest pathogen of three economically
important Cretan vegetables, tomato, pepper and eggplant was examined. Pathogen
development in culture medium or on fruits was evaluated after treatment with dittany
EO (0, 50, 100, 250 ppm) in vitro and in situ when stored at 12°C and 95% RH during
or following exposure to EO volatiles. The impacts of short term exposure of B. cinerea
to volatiles on growth and sporulation were also studied. Fungal development in vitro
was completely inhibited by the continued application of 100 or 250 ppm of EO
volatiles while inhibitory effects were also marked by lower EO concentration and short
time of exposure. In inoculated fruits the 50 ppm of EO application resulted in
suppressed disease development by reduced lesion growth and fungal sporulation,
where increasing EO concentration led to greater effects. Pre-exposure of fruits to
volatiles before fungal inoculation revealed reduced lesion growth, indicating that
dittany EO probably caused induced resistance of fruits against the pathogen. Moreover,
EO application did not affect quality-related characteristics of fruits while skin lightness
and pulp lightness of eggplant fruits was improved under the presence of dittany
volatiles. Overall, the results suggest that dittany EO volatiles may be considered as an
alternative food preservative treatment, significantly reducing or eliminating B. cinerea
infection during fruit storage and perhaps also in transit.
