Blueberry (Vaccinium corymbosum L.) postharvest UV-B treatments induce changes in bioactive compounds and reduce weight losses during cold storage

Postharvest management of blueberry is challenging. Complications are related to the monitoring of ripeness, which is manifested by the colouring of the peduncle area. This results in premature harvesting, with possible retrogradation during storage as consequence of a decrease in bioactive compounds and reduction in quality characteristics. Aiming to mitigate these complications, the effect of increased artificial UV-B radiation on the nutraceutical compounds of ‘Cargo’ blueberries (Vaccinium corymbosum L.) was evaluated. Blueberry samples, from pot-based production, were homogeneously harvested partially unripe (peduncle area still green/pink) and immediately processed under UV-B action. UV treatments were performed with a total peak emission, at 310 nm, of 18.58 W m‑2. Two exposure times (5-20 min) were performed in triplicate, then the samples were stored for 1, 2, and 24 h at 20°C (adaptation time) in a perforated plastic box, thereafter cold stored at 2°C for 6 days (storage time) and finally processed for qualitative analyses. The findings show that shorter treatments and longer adaptation times resulted in significantly greater accumulation of anthocyanins than the control. Short irradiation (5 min) caused some marked changes in fruit pigmentation, characterized by a colour change towards darker shades than the control. It was observed that the treatment improved in samples kept in the chamber at 20°C for 2 h. In addition, the results for weight loss during cold storage remain lower than the control. On the other hand, the samples seem to be negatively affected by the UV dose: the firmness of the berries decreases significantly with increasing exposure to lamps. Thus, anthocyanin accumulation between adaptation times is quite similar and the mechanical properties are better preserved with short UV treatments. Therefore, low doses would be promising to improve postharvest management. These latter results would provide consumers with fully ripened, defect-free products rich in nutraceutical compounds.