Effect of Water Treatment and Immersion in Calcium Salt Solutions on the Quality of Fruits of Peumo Pink Tomato (Solanum lycopersicum L.) Stored under Cold Conditions

Key words: calcium chloride, calcium lactate, calcium propionate, postharvest, heat treatment, heat shock protein Tomato is one of the most consumed vegetable crops worldwide. In the break stage, it is perishable, and it has a postharvest life that does not exceed three weeks at 12 to 15C. The aim of this study was to evaluate the effect of immersion in water and in calcium salt solutions on the metabolism and quality of tomato of traditional Peumo Pink cultivar stored for 28 days at 10C plus a simulated trading period of 2 days at 20C. Fruits were treated in water at 5, 45 and 60C at two immersion times of 1 and 4 min or in 2% solutions of calcium chloride, lactate and propionate at 10 and 45C for 4 min. The respiration rate, ethylene production and heat shock protein gene expression as well as firmness, total phenolic content and antioxidant capacity of tomato were determined. Dipping in water at 60C reduced the loss of firmness and respiratory rate of tomatoes up to 21 days at 10C + 2 days at 20C. Treatment in water at 45C for 4 min and at 60C for 1 or 4 min stimulated heat shock protein gene expression. However, fruit treated at 60C for 1 or 4 min showed uneven ripening; hence, the immersion in water at 45C for 4 min was the most recommended to extend the postharvest life of tomatoes. In turn, the immersion in calcium lactate and propionate solutions at 45C increased total calcium content and maintained firmness after 28 days at 10C + 2 days at 20C. The use of high temperature and calcium salts for dipping would be beneficial to provide the vegetal tissues with calcium and reduce the softening of the tomato after prolonged cold storage.