Shelf-life extension of tomato (Solanum lycopersicum L.) using an edible coating of bitter almond gum-fish gelatin conjugates

Abstract

Edible coatings can potentially reduce postharvest losses of tomatoes and preserve their health-benefit nutrients. We proposed that fish gelatin (FG) conjugated with bitter almond gum (BAG) may be suitable material for edible coating. Accordingly, coating dispersions were prepared with BAG, FG, or conjugates (1:2, 1:1, 2:1), and their effects were then investigated on the physicochemical and quality parameters of tomatoes during 28 days of storage at 20 °C. The occurrence of conjugation was assessed by scanning electron microscopy, Fourier transforms infrared spectroscopy, and rheological tests. The apparent viscosity and viscoelastic parameters improved proportionally to the BAG ratio in the conjugates. The conjugate-based coating maintained most tomato physicochemical parameters better than simple coating. Also, the conjugates preserved better sensory attributes and overall acceptability. However, the coating type did not affect pH, titrable acidity, and color indices apart from hue angle. Overall, BAG:FG (2:1) conjugate significantly delayed changes in firmness, lycopene content, titratable acidity, and limited weight loss and decay percentage to exhibit a protective performance for preserving tomatoes. Therefore, the conjugation FG with a higher BAG ratio can be promising to produce coating dispersion and maintain fruit quality during storability.