Postharvest UV-A and UV-B treatments may cause a transient decrease in grape berry skin flavonol-glycoside contents and total antioxidant capacities

Kristóf Csepregi, László Kőrösi, Péter Teszlák, Éva Hideg

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Controlled postharvest abiotic stresses have already been shown to affect the secondary metabolism of fresh produce. We applied broad band ultraviolet (either 312 nm centred UV-B or 355 nm centred UV-A) radiation on harvested berry clusters of the red table grape Emperor, and measured berry skin antioxidant capacities and phenolic profiles 2, 24 and 48 h after these treatments. There was no significant change in the amount of caftaric acid, the dominant phenolic acid component featuring higher UV-B than UV-A absorbing capacity. On the other hand, but both types of UV treatment decreased the amounts of the two major quercetin-glycosides 2 h after irradiation. This effect was temporal, and concentration recovered during berry storage at 20 °C under low intensity light. Berry skin UV-A and UV-B absorbing capacities showed the same, transitional decrease regardless of the wavelength of the irradiation. In the whole data set, antioxidant capacities and quercetin-glycoside content data showed strong and positive correlations. Berry skin peroxidase activity, as visualized with diaminobenzidine-staining showed a transitional increase after 2 h in response to both UV treatments. These data suggest that the observed UV-induced postharvest changes in phenolic metabolites are related to the oxidation of flavonols as peroxidase substrates rather than to direct UV photo-effects.

Original languageEnglish
Pages (from-to)63-68
Number of pages6
JournalPhytochemistry Letters
Publication statusPublished - Jun 2019



  • Berry skin
  • Peroxidase
  • Phenolic content
  • Postharvest UV-treatment
  • Total antioxidant capacity
  • Vitis vinifera L.

ASJC Scopus subject areas

  • Biotechnology
  • Biochemistry
  • Agronomy and Crop Science
  • Plant Science

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