Factors Affecting Carbon Dioxide Concentration in Interstitial Air of Wheat Stored in Hermetic Plastic Bags Silobag)

摘要

In 2007 about 35 million tonnes of grains were stored in hermetic systems (silo-bags) in Argentina,and about 5 million tonnes of that was wheat. The wheat stored in these silo-bags was mostly used for milling (internal and external market), but also for seeds for the next planting season. The goal of this research was to conduct a series of field experiments in order to identify the main factors affecting the carbon dioxide （CO2) and oxygen （O2) concentrations, as an indicator of biological activity and appropriate wheat storability conditions. The experiments consisted of monitoring the gas composition of the interstitial air,grain commercial quality, grain moisture content (MC),and grain temperature of several silo-bags. The main results indicated that the CO2 concentration of wheat stored in hermetic plastic bags increased with grain MC. At MC below 13% the CO2 concentration was below 5%,and as mold become active at higher MC the CO2 concentration increased to 30% for MC of 19%. Silo-bags with good quality wheat resulted in lower CO2 concentration than silo-bags with poor quality wheat at the same MC, implying that poor quality wheat had higher biological activity (CO2 concentration up to 7 percentage points higher). The effect of average grain temperature on CO2 concentration became substantial when grain MC was above 14%. For silo-bags with wheat MC higher than14% the CO2 concentration was higher during the warm season than during the cold season, and this difference was up to 7 percentage points when wheat MC was between 16% and 17%.