Calcium Nanoparticles Plus Amino Acids Improve the Antioxidant Content and Fruit Quality of Tomato

The content of bioactive compounds in fruits has become increasingly important to consumers in terms of high consumption levels, quality and shelf life. In addition, as the potential beneficial effects of bioactive compounds on human health become more widely known, products with longer shelf life are required. Against this background, the aim of this study was to determine the effect of calcium nanocomposites plus amino acids on tomato plant growth, fruit quality and antioxidant content. Specifically, the impact of the treatments on the physicochemical parameters of the fruits (colour of the fruits, thickness of the pericarp, hydrogen potential (pH), electrical conductivity (EC), total soluble solids (TSS) and fruit firmness), as well as the content of lycopene and <i>β</i>-carotene, vitamin C, phenols, flavonoids and total proteins, was verified. Calcium nanoparticles (Ca NPs) plus four different amino acids (<i>γ</i>-aminobutyric acid [AA], arginine [ARG], glutamic acid [AG] and alanine [ALA]) were applied as foliar treatments. The results showed that there were no negative effects due to the application of Ca NPs plus amino acids. On the contrary, they significantly affected the antioxidant content of tomato fruits and their physicochemical properties. The lycopene and vitamin C contents in the fruits were increased by Ca NPs + ALA and Ca NPs + AG treatments, respectively. Furthermore, the application of Ca NPs plus amino acids improved the lightness (L) of the fruits and reduced their yellow colour (b^∗). In addition, all treatments induced a lower loss of firmness of the fruits during postharvest, while Ca NPs + AA reduced the percentage of weight loss. The application of Ca NPs plus amino acids can be a viable option in the production of agricultural systems to improve the fruit quality and shelf life of tomato fruits.