The Characteristics of Gas Exchange for Purge-type in a Controlled Atmosphere Storage System

Abstract

The O2 and CO2 concentrations in controlled atmosphere (CA) rooms are determined by the respiration of produce like apples and the airtightness of the CA room, with gas in the CA room controlled by O2 and CO2 removal as well as respiration (CO2 increase and O2 decrease). The purpose of this study was to evaluate the validity of the gas exchange model for O2 removal, CO2 removal, the rate of O2 decrease and CO2 increase by respiration of apples, and airtightness of the CA room. It took 17.5 hours to reduce O2 concentration from 20.9% tO 2.0% after loading 4.3 tons of Fuji apples into the CA room, which was 4.2 hours longer than the 13.3 hours of the model formula. After the CO2 concentration rose to 0.5% due to respiration, it took 4.7 hours to lower the CO2 concentration to 0.2%, which was 0.6 hours longer than that of the model equation. The rate of CO2 increase by respiration was 0.021%/h, which was similar to the model equation (0.017%/h). Also after 4.7 hours, the O2 concentration decreased by 0.1% which was also in line with the model equation (0.13%/h).

Spoilage Monitoring and Early Warning for Apples in Storage Using Gas Sensors and Chemometrics

“…Meanwhile, the field layout prototype needs to be small and high-precision with low power consumption and high accuracy to meet the needs of spoilage monitoring. After extensive research and experiments, the main gases in the apple quality and spoilage process were determined, and C 2 H 4 , CO 2 , volatile organic compounds (VOC) and O 2 were optimized to be the characteristic gases of the apple warehouse [17][18][19][20]. An infrared gas sensor was selected for the CO 2 sensor, and the remaining sensors were electrochemical gas sensors.…”