The present invention relates to methods for increasing the content of nutraceuticals and antioxidant capacity of perishable fruits, by combining irradiation with ultraviolet light (UV-C) and storage at freezing temperatures in different presentations. According to the invention, it is possible to increase the concentration of flavonoids, such as phenols and anthocyanins, and also the antioxidant capacity of strawberry fruits (Fragaria x ananassa). The main objective of the present invention is to improve the postharvest quality of fruits, particularly strawberry, by stimulating strawberry fruits with different doses of UV light and different temperatures.