DEVELOPMENT AND EVALUATION OF A PORTABLE FORCED AIR PRE-COOLING UNIT

Abstract

A study was carried out at the experimental station of RiceMechanization Center (R.M.C.), Meet El-Deyba, Kafr El-Sheikh Governorate, during 2007 and 2008 seasons. The experimental work included design, developing and testing a portable pre-cooling unit for fruits and vegetables. Quality changes of the pre-cooled products in comparison with the none cooled product were also determined during storage process under two different storage conditions (coled and room storage methods). The laboratory experiments were conducted for pre-cooling tomato fruits at three different levels of air temperature (4, 7 and 10oC), three levels of air velocity (3.7, 4.8 and 5.4 m/s), three levels of packages vents percentage (4, 6 and 8%) and two volumes of fruits (medium and large).The results showed rapid drop in product temperature at the beginning of cooling process and the cooling rate starts to decline as the product temperature approaches the final temperature. The values of cooling coefficient (C) increased with the increase of air velocity (V), increase of packages vents percentage, decrease of fruit volume and decrease of medium cooling air temperature. While, the half and seven-eighth cooling times decreased with the increase of air velocity and increase of packages vents percentage and they were increased with the increase of cooling temperature and increase of product volume. The storage experiments showed that, the pre-cooled tomato fruits recorded lower water loss, lower percentage of defect, and higher fruit firmness in comparison with the none cooled samples.