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: FoodAdditional key words: inside temperature, postharvest loss, relative humidity, shelf life, storage

Evaluation of temperature and relative humidity on two types of zero energy cool chamber (ZECC) in South Sulawesi, Indonesia

“…In average, the temperature in the outside is higher than in inside of the ZECC, particularly in daylight. For instance, while the temperature in T1 (inside + underground + watering) and T2 (inside + surface + watering) of the ZECC at 5 hours is about 27.1 0 C and 26.3 0 C, respectively, the corresponding values for T0(outside) is about 33.3 0 C. This result was consistent with a study by Islam and Morimoto [1], in which the temperature of the ZECC investigated; the temperature inside of the ZECC is lower than the outside one. As a result, the temperature inside of the ZECC can be potentially reduced using watering for the sand.…”

“…Liquid water molecules of the moist sand-zeolite mixture gasify under the influence of outside air through a process that uses energy to change the physical state. Convection and conduction were heat transitions that happened from the higher temperature of the air and brick walls to the lower temperature of water [1]. There is a drop in ambient temperature during this conversion process.…”

“…The design was based on the evaporative cooling of a porous body [1,7,9,10]. Two different of ZECC were constructed.…”

“…The farmers have no storage facilities, while the transport and commercialization channels also lack storage facilities. As a result, most harvested fruits and vegetables are usually stored in the open, exposed to high temperatures and low relative humidity conditions, until an intermediary, retailer purchases those commodities [1]. The combination of higher humidity and lower temperature facilitates extended shelf life.…”

“…The use of a shading curtain is also an effective means of reducing the temperature. Higher humidity and lower temperature inside the zero energy cool chamber (ZECC) offers a unique advantage for maintaining the firmness of fruits and vegetables by lowering the physiological loss in weight (PLW) and other metabolic processes [1,2]. Some studies on constructing and applying ZECC have been conducted.…”