Postharvest UV-C treatment increases bioactive, ester volatile compounds and a putative allergenic protein in strawberry

- PL genes may play an important role in flesh firmness of UV-C treated strawberry.
- UV-C treatment increases total anthocyanin and phenolic compound levels.
- UV-C up-regulates LGalDH and GLDH genes resulting in higher l-ascorbic acid.
- UV-C treatment increases ester volatile compounds.
- UV-C treatment seems to induce accumulation of the allergenic protein Fra a1.

UV-C treatment applied during postharvest to control fruit decay has been shown to interfere with several aspects of fruit quality. In this study, strawberry fruit (Fragaria × ananassa Duch., cv 'Aromas') harvested at the 75% red stage of ripening were treated with UV-C (4.35 kJ m−2) and postharvest compounds indicative of quality, as well as related gene transcripts, were measured. UV-C effect in two allergenic proteins was also evaluated. After treatment, fruit was stored for six days at 20 ± 2 °C and 80 ± 5% relative humidity (RH). UV-C treated fruit maintained flesh firmness and showed lower pectate lyase transcript accumulation than control fruit. UV-C treatment increased total anthocyanin and phenolic compounds, including gallic acid, hydroxybenzoic acid, ρ-coumaric acid, quercetin and (+)-catechin. UV-C treatment also increased l-galactose dehydrogenase, l-galactono-1,4-lactone dehydrogenase, alcohol dehydrogenase and alcohol acetyl transferase transcript accumulation, and resulted in strawberries with higher l-ascorbic acid content and higher volatile compound production. In conclusion, UV-C treatment induces a variety of changes in the strawberry primarily via gene activation, resulting in firmer fruit with higher levels of bioactive molecules, as well as a stronger aroma. However, UV-C also induced accumulation of the putatively allergenic protein Fra a1.