Impact of storage period and nanoparticle treatment on phytochemical composition of watermelons (Citrullus lanatus)

Abstract

The nutritional quality of many fruits and vegetables is regulated by pre-harvest management factors that can be manipulated to attain desired quality standards. In this study, the impact of seed nanopriming on the phytochemical composition of watermelon was studied. Seeds of two watermelon varieties namely: River Side (diploid) and Maxima (triploid) treated with two nanomaterials (silver nanoparticle and turmeric nanoemulsion) along with untreated seeds were grown in five locations over two seasons. Physico-chemical properties and phytochemical profiles were assessed after mature fruits were harvested and stored at 23 °C for 0, 10, and 20 d. Key physico-chemical characteristics that were impacted by storage included fruit weight, rind thickness, pH, and soluble solid content. Similarly, levels of health-promoting compounds such as carotenoids, l-citrulline, and total ascorbic acid were maintained and/or enhanced in watermelons after 10 d of storage compared to untreated fruits at harvest. However, l-citrulline (10.40 g/kg) and total ascorbic acid (57.52 g/kg) was significantly reduced in watermelons after 20 d of storage (8.6 and 19.09 g/kg, respectively) regardless of treatment and location (p < 0.05) in River Side and the trend is similar in Maxima. Combined analysis across all locations demonstrated non-significant treatment effect on the levels of health-promoting compounds among the control and the nano-treated watermelons. These observations suggest that seed priming with nanomaterials does not have any detrimental effect on the fruit's nutritional quality and the consumer’s health.