About a year and a half ago I posted about long term storage of rice using dry ice for purging oxygen in the container. I recently decided to open one of the containers and see how well this approach to storage had worked.
If you look at the photo in that post from last year you can see how the plastic water container had been slightly collapsed by the partial vacuum formed inside due to the absorbtion by the rice of some of the carbon dioxide sublimated by the dry ice. That same partial vacuum was still present when I pulled the container from my food bunker and there was a distinct whoosh of air entering the container when I cracked the seal. Conclusion – these containers form an air tight seal and have minimal gas permeability at least for period of 16 months.
A close look at the rice showed it looked as good as new and there was no infestation of any kind visible. That’s good because around here when we try to save rice for a long period it becomes infested within a few months with some kind of small bug that eats it and turns it to powder. The same thing has happened with things like spaghetti noodles. This doesn’t happen every time or with every product we purchase but it is frequent enough that some action must be taken to prevent the loss of the product. Although I am not sure, I believe the bugs come with the packaged product and don’t enter while in storage. I have read that it is common for there to be eggs or larvae in products like this.
Regardless of the vector and the product, it does appear that the dry ice method is effective for long term storage of rice in an air tight container with low gas permeability. I have another container of rice that was packaged at the same time as the first that I will keep in storage for another year at least and report on results then. I also plan to store additional rice as well as dried beans in the same manner.
I have not yet found a good container for storing products that aren’t the convenient shape of grains. The five liter water bottles I am using for rice are inexpensive (as in free), good quality, and just the right size since we buy five kilogram bags of rice that fit entirely in the bottles with just a small air space at the top. One of those packages gets used in a couple of weeks under normal conditions in our household so the amount is just right. Noodle products like macaroni would also store nicely in the water bottles. But sphagetti and similarly shaped noodles don’t work. A container with a wide mouth would work but getting a reliable seal becomes more of an issue as the size of the seal becomes larger. That translates into expense. So it would seem I need a large number of modest sized containers with a mouth and body of the same size that have a high quality seal. That is not going to be cheap, and I haven’t found them yet anyway.