Using Response Surface Methodology to Optimize Edible Coating Formulations to Delay Ripening and Preserve Postharvest Quality of Tomatoes

Tomato is a nutrient-rich but highly perishable fruit. In order to delay the rapid ripening and degradation of fruits and reduce postharvest losses, response surface methodology (RSM) was used as the optimizing method to formulate edible coating based on pineapple peel extract and Arabic gum of twenty concentrations of pineapple (0.5-0.83 kg/l) and 20 concentrations of Arabic gum (5-15%, w/v). Tomatoes were soaked for 10-30 min in any of the coating solution. Five parameters including ripening rate, chlorophyll a content, firmness, total flavonoid content, and titratable acidity of tomatoes were evaluated after 8 days of storage at 24 +/- 0.5 degrees C and 82 +/- 1.5% relative humidity. Results showed that the experimental data could be adequately fitted into a second-order polynomial model with coefficient of determination (R-2) ranging from 0.775 to 0.976 for all the variables studied. The optimum concentrations were predicted as 0.70 kg/l pineapple peel extract and 17.04% with 18.72 min optimum time. Under these conditions, predicted values of response variables are as follows: ripening rate (RR) 40.75, chlorophyll a (Chl a) 8.11, firmness (Fir) 4.00, total flavonoid content (TFC) 43.51, and titratable acidity (TA) 0.30. It is concluded that RSM can be used to optimize pineapple peel extract and Arabic gum-based edible coating formulation to extend the shelf life or delay the ripening process of tomato fruit at ambient conditions.