Post-harvest UV-C and PL Irradiation of Fruits and Vegetables

The exposure to UV-C and Pulsed Light (PL) light causes stress in plant tissues, which stimulates the biosynthesis of defensive secondary metabolites with antimicrobial and antioxidant activity. For this reason, recent studies have examined the capability of UV-C and PL as effective methods to prolong the fresh status as well as preserve or even improve the content and activity of antioxidant compounds of fresh produce through post-harvest handling and processing. In this work, the effect of PL and UV-C treatments on quality and antioxidant properties of tomatoes and Annurca apples intended for fresh consumption was investigated. Fruits harvested at the green stage were exposed to both light treatments at energy dosages of 2 and 4 J/cm2. Treated and untreated samples were allowed to ripen under day/night cycles illumination conditions at room temperature for up to 21 days for tomatoes and 28 days for apples. The effects of light treatments on the colour, pH, titratable acidity and °Brix as well as on the levels of lycopene, total carotenoids, total phenolic compounds and antioxidant activity, were evaluated through storage and compared with those of untreated samples. Results indicate that pH, titratable acidity and °Brix of all fruit samples were not significantly affected by light treatments and remained almost the same throughout storage. The skin colour of untreated and exposed fruits changed during storage period, with no appreciable influence of the light treatments. However, the exposure of apples and tomatoes to light treatments enhanced the antioxidant properties of these fruits during storage. These results suggest that post-harvest PL and UV-C irradiation can be utilized to the health value of tomatoes and Annurca apples by increasing the level of certain bioactive compounds without inducing significant changes to their physical properties during storage