Effect of germicidal UVC light on fungi isolated from grapes and raisins.
OBJECTIVE
To examine how UVC affects the different genera of fungi commonly isolated from grapes, with the aim of understanding changes in mycobiota during grape ripening and possible applications for preventing grape decay during storage.


RESULTS
Spores of Aspergillus carbonarius, Aspergillus niger, Cladosporium herbarum, Penicillium janthinellum and Alternaria alternata (between 100-250 spores/plate agar) were UVC irradiated for 0 (control), 10, 20, 30, 60, 300 and 600 s. Plates were incubated at 25 degrees C and colonies were counted daily up to 7 days. Alternaria alternata and Aspergillus carbonarius were the most resistant fungi. Conidial germination in these species was reduced by approx. 25% after 10 s of exposure, compared with greater than 70% reduction for the remaining species tested. Penicillium janthinellum spores were the most susceptible at this wavelength. UVC exposures of 300 s prevented growth of all isolates studied, except for Alternaria alternata.


CONCLUSIONS
UVC irradiation plays a major role in selecting for particular fungi that dominate the mycobiota of drying grapes.


CONCLUSIONS
The UVC irradiation of harvested grapes could prevent germination of contaminant fungi during storage or further dehydration.
Valero
A
A
Food Technology Department, University of Lleida, UTPV-CeRTA. Av., Lleida, Spain.
Begum
M
M
Leong
S L
SL
Hocking
A D
AD
Ramos
A J
AJ
Sanchis
V
V
Marín
S
S
D003904:Mitosporic Fungi / Q000302:isolation & purification / Q000472:pathogenicity / Q000528:radiation effects*; D013997:Time Factors; D014466:Ultraviolet Rays; D027843:Vitis / Q000382:microbiology*