Zero Energy Cool Chamber for Extending the Shelf-Life of Tomato and Eggplant

Abstract

A zero energy cool chamber (ZECC) consisting of a brick wall cooler and a storage container made of new materials has been developed. The ZECC requires no electric energy. The brick wall cooler made of bricks with a mixture of moistened sand and zeolite allows low inside temperature and high relative humidity to be maintained based on the principles of a natural evaporative cooling mechanism. Several types of storage containers coated with different antibacterial materials were applied to reduce decay. For example, silver-ion-coated storage containers were used to reduce decay. Heat treatment was also applied to the commodities in order to maintain freshness. Generally, tomato and eggplant had a shelf life of 7 and 4 days at room temperature, respectively, as compared to 16 and 9 days when stored in the ZECC. Tomato and eggplant treated with hot water reduced the percentage of rotting. Tomato treated with hot water at 60°C for three minutes and eggplant treated with hot water at 45°C for an hour when stored inside silver-ion-coated containers in the ZECC showed extended shelf life of up to 28 and 15 days, respectively. Discipline: Food Additional key words: inside temperature, postharvest loss, relative humidity, shelf life, storage *Corresponding author: e-mail morimoto@agr.ehime-u.ac.jp Received 5 July 2011; accepted 19 January 2012.