Application of Cu Nanoparticles in Chitosan-PVA Hydrogels in a Native Tomato Genotype: Evaluation of the Postharvest Behavior of the Physicochemical and Bioactive Components of the Fruits

The native tomato genotypes of Mexico are characterized by their good organoleptic properties and by a greater amount of active compounds than other tomato genotypes; however, they present a short shelf life. Therefore, in this research, copper nanoparticles were applied (Cu-NPs) in chitosan-polyvinyl alcohol (Cs-PVA) hydrogels in a native kidney-shape tomato genotype produced under greenhouse conditions and its effect on the postharvest behavior of the physicochemical components and bioactive compounds of the fruits was evaluated. The treatments applied to the substrate of the plants were 0, 0.57, 1 and 2 mg of Cu-NPs g −1 of Cs-PVA per plant, the effects of these treatments were compared to a control. The results showed that the application of Cu-NPs in Cs-PVA increases the concentrations of the bioactive compounds. Lycopene and β-carotene and the contents of the total phenols and flavonoids were 99.68 mg 100 g −1 DW, 24.60 mg 100 g −1 DW, 4.12 mg GAE g −1 DW, and 8.27 mg QE g −1 DW, respectively. The antioxidant activity was 24.33 µM Trolox g −1 DW, and all of these values were higher than those of the control. The fruits treated with 0.57 and 1 mg of Cu-NPs g −1 of Cs-PVA exhibited an increased total soluble solids and reduced weight loss of up to 50% less compared to that of the control. These results suggest that the application of Cu-NPs in Cs-PVA can be used to maintain physicochemical quality and increase the contents of bioactive compounds in native kidney-shape tomato fruits and thus prolong the storage period.