Antioxidant and nutritive constituents during sweet pepper development and ripening are enhanced by nitrophenolate treatments

A mix of nitrophenolates was applied to pepper plants in the irrigation system along the growth cycle. Fruits were labelled at fruit set to study the evolution of fruit growth and ripening based on fruit size and colour. In addition, at 3-day intervals, samples were taken in which the evolution of fruit weight, colour, nutritive (sugars and organic acids) and bioactive compounds (total phenolics, carotenoids, and ascorbic acid) was evaluated. Pepper fruit growth followed a simple sigmoid curve reaching its maximum size at 49 days after fruit set, although nitrophenolate treatments led to significant increases in fruit weight due to higher length, diameter, and pericarp thickness, without affecting the normal ripening process, since colour and carotenoid evolution was similar for both control and treated fruits. Glucose, fructose, ascorbic acid, citric acid, total antioxidant activity (TAA) and total phenolics increased during pepper development, and their levels were significantly enhanced by nitrophenolate applications. Thus, this treatment induced beneficial effects in terms of the improvement of fruit quality, and especially its nutritive and antioxidant constituents. Finally, it is advisable to consume peppers at the full red stage in order to achieve the maximum health-beneficial effects by consumers.