UV-B-induced changes of volatile metabolites and phenolic compounds in blueberries (Vaccinium corymbosum L.)

There are many reports on the potential consequences of UV-B radiation on plants, but there is a rather limited understanding of the effect on secondary plant metabolites, e.g. phenolic compounds and volatiles, at all. The popularity of highbush blueberries (Vaccinium corymbosum L.) is mainly due to its unique flavour and its high content of bioactive compounds, i.e. phenolic compounds. However, information on UV-B elicitor mediated changes on secondary plant metabolites on blueberries is scanty. In the present study, blueberry fruits were harvested and exposed to UV-B radiation with different dosage and adaptation times. With regard to volatile secondary metabolites, C₆-aldehydes, terpenes and ketones, an increase of the relative peak area was observed after both UV-B treatments (0.075 and 0.15 Wh/m² = low [L] and high [H] dosage, respectively). Furthermore, there was a strong influence of the adaptation time. Increasing relative peak areas were determined already after a short adaptation time (2 h) at both, low and high UV-B dosages, but after 24 h adaptation time relative peak areas decreased significantly. However, alcoholic compounds, as degradation products of aldehydes, showed opposite results. In contrast, the non-volatile phenolic compounds revealed a continuously increase with UV-B intensity.