Preharvest UV-C treatment improves the quality of spinach primary production and postharvest storage

Abstract

Preharvest low UV-C doses applied during spinach growth in the field as a preharvest tool could improve the antioxidant status, increasing the antioxidant compounds content and improving the resistnce to fungal damage. This physical treatment could replace or decrease the use of chemical treatments to control fungal diseases, which may leave unpleasant chemical residues in fruit and vegetables. In this study, two different UV-C (1.5 kJ m−2 and 3 kJ m−2) treatments were applied at three different development stages (I, immature; II, baby; and III, mature commercial stage) of the spinach in the field. Color, chlorophyll content, sensorial analysis, microbial load (mesophilic, molds and yeast), vitamin C content, total phenolic content (TPC) and antioxidant capacity evaluated by two different assays were evaluated after harvest and after storage for six days at 5 °C in darkness conditions. The immature leaves were more susceptible to UV-C, and 1.5 kJ m−2 or higher dose could affect plant development after several applications. In stage II a decrease in vitamin C content was observed after applying 3 kJ m−2. However, the TPC increased with the UV-C treatment and the number of applications. On the other hand, UV-C maintained the meshophilic and yeast counts during the spinach development in the field and reduced the mesophilic count after storage. Additionally, both UV-C doses applied in the field also showed an effect on the antioxidant status of spinach leaves during the storage. However, these UV-C treatments were not enough to reduce the mold counts in spinach leaves growth in the field and needs to be applied in conjunction with chemical treatments to prevent diseases.