Effect of Two Edible Coatings to Preserve Storage Life and Quality of Tomatoes Fruit During Storage

Tomatoes (Lycopersicon esculentum Mill.) are one of the most widely consumed fresh vegetables in world. Consumers judge the quality of fresh tomatoes by their firmness, color and taste, attributes that are related to fruit ripening and shelf life. Major losses in tomato quality and quantity occur between harvest and consumption; therefore, it is necessary to develop new methods to extend the shelf life of this commodity during post-harvest. One method is the application of edible coatings. The purpose of the present study was to evaluate carnauba and mineral oil coatings for their ability to preserve post harvest quality of tomatoes (cv. Grandela). Sta-fresh 2505™ (carnauba) and Sta-fresh 151™ (mineral oil) coatings were applied on tomatoes at two maturity stages (breaker and pink). The quality of tomatoes was evaluated periodically at 0, 5, 10, 15, 21 and 28 days of storage at 10°C, plus 2 days at 20°C. For respiration rate analysis, tomatoes were kept at 20°C for 16 days. The present study showed that coatings were effective in the preservation of tomatoes. Respiration rate, color, weight loss and enzyme activity were positively affected by mineral oil coating in both maturity stages. At the beginning of the study CO₂ production was reduced by 38% and 46% when applying the mineral oil coating on breaker and pink tomatoes, respectively; this reduction was observed during almost all the storage period. Ethylene production was entirely inhibited at the beginning of the study on both maturity stages, when mineral oil coating was applied. Ethylene production was kept significantly low during the first nine and 12 days of storage for breaker and pink stage, respectively. At the end of storage, mineral oil coating reduced tomato weight loss up to 70% and 46% for breaker and pink stage, respectively; the change of color was successfully retarded too. However, tomatoes treated with mineral oil showed an increase on the production of acetaldehyde and ethanol at day 5 of storage for both maturity stages.  No effect on firmness, acidity titratable and pH were found by the application of the coatings. Tomatoes treated with carnauba wax showed a similar pattern that control fruits for all variables studied, with exception of weight loss, where retention of weight was observed when applying carnauba coatings. In conclusion, mineral oil coatings could be a good alternative for preserving quality and extending the shelf life of tomato fresh fruit.