The influence of postharvest UV-C treatment on anthocyanin biosynthesis in fresh-cut red cabbage

Red cabbage (Brassica oleracea L. var. capitata f. rubra DC.) is a fresh edible vegetable consumed globally that contains high levels of antioxidant compounds including anthocyanins. In this study, fresh-cut red cabbage was treated with different Ultraviolet-C (UV-C) dosages. Fifteen cyanidin derivatives were observed in UV-C treated fresh-cut red cabbage; four of these were anthocyanins absent in control samples. The optimum dose of UV-C for enhancing total anthocyanin content in freshcut red cabbage was 3.0 kJ/m(2). Different UV-C irradiation doses resulted in miscellaneous responses for each of the anthocyanin compounds, and these alterations appeared to be dose-dependent. The expression of genes relating to anthocyanin metabolism was altered by UV-C irradiation. For example, genes for biosynthetic enzymes including glycosyltransferase and acyltransferase, as well as R2R3 MYB transcription factors (production of anthocyanin pigment 1 and MYB114), had strongly increased expression following UV-C treatment. These results are in accord with the roles of these gene products in anthocyanin metabolism. This is, to the authors' knowledge, the first report demonstrating that UV-C treatment can increase the antioxidant activity in fresh-cut red cabbage in storage. Moreover, our detailed phytochemical and gene expression analysis establish specific roles for both anthocyanins and metabolism genes in this process.