Efficacy of non-chlorine sanitizer, precooling and modified atmosphere packaging in improving shelf life of tomato during evaporative cooling and CoolBot cold storage

Abstract

This study combined the use of non-chlorine sanitizer, precooling and modified atmosphere packaging (MAP) as prestorage treatments for tomato kept in a simple evaporative cooler (EC) or CoolBot cold storage (CS). Precooling was done by dipping the fruit in 10°C water until fruit temperature decreased to 13-15°C. As a non-chlorine sanitizing treatment, dipping fruit in 0.01% calcinated calcium (CCa) for 5 min at ambient temperature was used. For a combined precooling and sanitizing treatment, 10°C CCa solution was used. Tomatoes were stored in the EC or CS. Ambient storage was included for comparison. Fruits of a summer tomato cultivar, 'BARI Tomato-8', were used in this study. EC temperatures (24.3-27.5°C) were consistently lower and less fluctuating than ambient temperatures (27.8-31.0°C). The CoolBot temperature was maintained at 13±1°C. RH was about 75±2% in CS, whereas it was 75-95% under ambient conditions and 85-99% in the EC. Because of these conditions, together with the relatively high temperatures, fruit rotting was favored and limited the shelf life to 12-13 days, both under ambient conditions and in the EC. Fruit in the CS lasted for 18 days. Rotting affected ˃50% of the fruit on day 15 of ambient storage and of EC storage. In the CS, fruit rotting was first noted on day 9, increased gradually, and reached around 14-18% on day 18. Sanitizing treatment had little effect, but precooling had no extra benefits in reducing rot incidence. MAP significantly reduced weight loss in all storage conditions, showing a greater effect in the CS. Changes in fruit firmness and surface color were delayed significantly in CS compared with ambient conditions or EC storage. After 18 days of storage, the firmness of tomatoes remained higher when stored in CS, showing values of about 5.0 N. Vitamin C content was effectively maintained in the CS, and was about 12.6 mg 100 g-1 after 18 days of storage. EC- and ambient-stored fruit, on the other hand, had similar vitamin C contents at the end of their 12-day storage life.