PERFORMANCE EVALUATION OF DIFFERENT POROUS MATERIALS USED IN THE ZERO ENERGY EVAPORATIVE COOLING CHAMBER FOR STORAGE OF WHITE SAPOTE (casimiroa edulis l.) FRUITS UNDER DIRE DAWA CLIMATE CONDITIO

Abstract

High percentage (>40%) of fresh produce is lost in Ethiopia after harvest due to lack of properstorage and transportation facilities. This problem needs solution through use of af ordable appropriate technologies that can be developed using local resources. Use of ZECC constructed from clay bricks with three cooling pads viz. sand, sawdust and charcoal was studied using white sapote fruits. Cornstarch mixed with lemon and ginger extract to play antimicrobial rolewas employed as coating material. The experiment was conducted with two factors viz. cooling pad and edible coating consisting of twelve treatment combinations with ambient storage and uncoated fruits as control. The study was conducted for 18 days of storage time assessing various quality parameters of the stored fruits at 3 days interval. The environment data in the storage indicated that temperature dropped by6-10.2 oC as compared to the24.5-32 oC of the ambient and the relative humidity was raised to 88.2, 85.1 and 87.6% for the cooling pads of sand, sawdust and charcoal, respectively, as compared to 47.59% of the ambient air. The three pad materials resulted in cooling ef iciencies of 91.22, 87.95, and 87.82%, respectively. The shelf life of the fruits was very much prolonged as expressed in terms of various quality attributes. The marketability of the fruit stored in ZECC was above 40 % by day 18 as compared to 30.44% on day 12 for the ambient stored samples. The weight losses of fruits stored in ZECC were around 17% on day 18 whereas a similar loss was recorded for sample stored under ambient condition by 12 th day. Generally, the ZECC storage had shown significantreduction in loss of all quality attributes of the fruits. The three pad materials did not show significant dif erences among them in performances. Likewise, the lemon and ginger extracts used in the coating showed no dif erence between them in their performance but had significantly improved achievements as compared to uncoated samples. Further study should be conducted on the properties of those porous materials and on other locally available cooling pads. Further investigation isalso needed on impact of edible coating on the nutritional composition and on harvesting methods of white sapote fruit