The Studies On CO₂Produced By Mold Activities Of Storaged Grain And Its Diffusion Law In Grain Bulk

In order to aviod grain irreversible loss which caused by mold, it is critical to detect tostored grain mold early, but there is not a very good technology among all the mold detectionmethods. It is promising of using CO₂concentration to monitor the activity of grain mold, notonly to achieve remote automation online, but also not to collect grain samples from granary.The fomation of CO₂in grain bulk and its changes were investigated at definite temperature,airtightness, mildew site, mildew quantity and grain categories. At the same time, the loss rateof CO₂in untightness grain bulk and the place of moldy grain were discussed. Therefore, it’sbeneficial for the early control of stored grain mold activity to research CO₂produced bymold activities and its diffusion law in grain bulk.The fomation of CO₂in grain bulk were studied. The results showed that CO₂produced bymold was in dominant in moldy grain, and there was not moldy grain in tightness granary, thechange of CO₂concentration was not significant. However, when there was moldy grain, CO₂concentration was significantly increased in the local part, and CO₂concentration among thebottom, middle, upper and surface of grain bulk was significant. So detecting the change ofCO₂concentration in grain bulk could be effective monitoring of mold activity.Impact of temperature, airtightness, mildew site and mildew quantity on the change of CO₂concentration in grain bulk were further researched. Results indicated that the temperaturewas higher, the airtightness was better, and the mildew quantity was more, the diffusion ofCO₂was more apparent. In the vertical direction of grain bulk, the change of CO₂concentration was significant in the layer of mildew grain, and in the horizontal direction,CO₂concentration was higher near the mildew point, with the distance increasing, CO₂concentration performanced that the bottom> middle> upper> surface. Different types ofresults showed that wheat, corn and rice bulk accumulated CO₂concentration was4.876%,4.454%,3.956%when storaged35d, the CO₂concentration was different, but the diffusionlaw was same.By comparing the loss rate of CO₂in wheat and core untightness bulk, it was found thatthe concentration of CO₂decreased rapidly when the release of the source was removed.Storaged0.5d, CO₂concentration, decreased by74%in wheat bulk and82%in corn bulk.With the extension of storage time, CO₂concentration tended to the uniform distribution inthe grain bulk. The decision of grain mold sites showed that the diffusion of CO₂was same at the same mold site, the CO₂diffusion changed when the mold site changed. Thereforedetecting the changes CO₂concentration in the grain bulk could be provided reference todeterminate the grain moldew site and improved the forecast theory of grain mold activities.