Ultraviolet-C and induced stilbenes control ochratoxigenic Aspergillus in grapes.
This study investigated the efficacy of ultraviolet-C (254 nm) and induced stilbenes to inhibit Aspergillus carbonarius and Aspergillus tubingensis and control ochratoxin A production in grapes. In addition, the stilbene synthesis as a response to UV-C treatment and to infection of ochratoxigenic Aspergillus was compared. The initial microbial inactivation by a previously optimized UV-C illumination protocol for increasing trans-resveratrol content in grapes (50 W/m (2), 40 cm, 60 s) was similar on undamaged and damaged grapes, achieving 1.2 and 1.3 log conidia/100 g reductions, respectively. After 5 days of storage at 22 degrees C, UV-C treatment and the stilbenes induced by UV-C inhibited ochratoxigenic Aspergillus growth in undamaged grapes. UV-C elicited the biosynthesis of trans-resveratrol, while microbial infection and tissue damage triggered the biosynthesis of trans-piceid. trans-Resveratrol was not synthesized as a consequence of ochratoxigenic Aspergillus contamination. However, when trans-resveratrol was synthesized by UV-C, it contributed to inhibiting the development of ochratoxin A producing aspergilli. Furthermore, UV-C treatment also contributed to decrease ochratoxin A production by ochratoxigenic aspergilli. Therefore, UV-C is a promising emerging technology either for reducing the potential ochratoxigenic risk in grapes, which is of particular interest to the wine industry, and also for increasing trans-resveratrol content of grapes, which would provide an added value to the wine.
Selma
María V
MV
Research Group on Quality, Safety and Bioactivity of Plant Foods, CEBAS-CSIC, Murcia 30100, Spain.
Freitas
Paula M
PM
Almela
Luis
L
González-Barrio
Rocío
R
Espín
Juan Carlos
JC
Suslow
Trevor
T
Tomás-Barberán
Francisco
F
Gil
María I
MI
D001230:Aspergillus / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects*; D005514:Food Irradiation / Q000379:methods*; D009793:Ochratoxins / Q000378:metabolism*; D013267:Stilbenes / Q000378:metabolism*; D014466:Ultraviolet Rays; D027843:Vitis / Q000737:chemistry / Q000378:metabolism* / Q000382:microbiology / Q000528:radiation effects*
D009793:Ochratoxins; D013267:Stilbenes; C025589:ochratoxin A