Thermal shock with combined calcium in tomato tolerance induction to cold storage.

Abstract

This study evaluated the effect of thermal shock, combined with calcium in the microbiological and biochemical response of tomatoes stored under refrigeration. Heat shock treatments (45 ° C for 12 minutes under water) combined with calcium (CaCl 2) were applied to tomatoes. After treatments, fruits were stored at 5 ° C for 10 days, with subsequent storage at 20 ° C for 10 days. The activity of peroxidase (PO), the contents of β-carotene, lycopene, phenolics and ascorbic acid and also the incidence of pathogens were evaluated. The results showed no effect of heat shock and its combination with Ca on the activities of PO and the ascorbic acid content of tomatoes submitted to cold stress. Significant influence on the total phenolic content of tomatoes under cold stress occurred only when the thermal shock was apply with calcium, with accumulation below the control. The use of thermal shock in tomatoes submitted to cold stress showed effectiveness in reducing the incidence of pathogens, which allows for greater shelf-life of fruits stored under refrigeration. The combination of calcium with heat shock was less effective in controlling fungal incidence compared to heat shock alone would not compensating for its use. Symptoms of chilling injury due to senescence and development of pathogens were not found in tomatoes treated with heat shock isolated, revealing itself as an effective method in promoting tolerance of fruit to cold stress.