Dry ice is ideal for purging oxygen out of containers of grain, thus making them inhospitable places for insects, grubs, weevil or other insects. Absence of oxygen improves shelf life of the food. Replace oxygen with CO2 (dry ice).
Use this presentation below with your group to show how to preserve food using dry ice.
1. Feature photo by gullevek at www.flickr.com/photos/gullevek/186807641/