Archive for the ‘World’ Category

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. TheĀ  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.

I keep reading about how teens and early twenty-somethings are clueless about how things were done just a few years ago before everybody had smart phones. The fact that they have such vast resources available in the palm of their hand seems to actually be making them a lot dumber and unable to do even the simplest things themselves. This comic made the point pretty well I think.

homework class test - School of Fail: Kids These Days Just Have No Damn Respect.

I feel like I am part of the advantaged generation, having knowledge of actually how to do things and greatly appreciating the resources now available to anyone with a wireless or internet connection.

I’ve been wanting to build up a long term store of food but face a few issues here. One issue is the weather – hot and humid most of the year which makes keeping foods cool and free of molds and fungi a challenge. Another issue is pests – anything like rice, beans or pasta gets infested with weevils after just a couple of months even if the package remains sealed.

Much of the information I have read online talks about refrigeration or freezing for long term storage of grains. That is not practical or cost effective for large amounts. I read some studies that compared preservation by refrigeration and by dessication. Good preservation results were obtained with super dessication and no need for costly refrigeration (equipment and power). Elsewhere there is quite a bit of discussion about the importance of eliminating oxygen from the storage container to inhibit molds, fungi and pests. Apparently there is a tradeoff here – if you put an oxygen absorber and a dessicant into the same storage container they battle each other. At least that’s what I read, not sure if it is accurate.

Regardless, I haven’t been able to find a local source of either oxygen absorbers or a suitable dessicant. Instead I have gone with using dry ice to purge the storage containers of oxygen by filling them with carbon dioxide as the dry ice sublimates. The method is easy and I was able to locate a local source of dry ice. One kilogram of dry ice costs only 25 baht which is about US$0.80 at the time of this writing.

The storage containers I am using are five liter plastic water bottles made of PETE. This is the very common clear semi-rigid plastic used for water and soft drink bottles. PETE is a pretty good oxygen barrier, although it isn’t as good as some other materials. Glass containers with air tight lids and containers made of other materials are difficult to find locally and are quite expensive. These five liter water bottles are readily available and inexpensive so if they perform well enough then they will remain my primary choice.

So I did my first batch. Rice is available in five kilogram bags which fill almost completely one of the five liter bottles. The process is simply to drop some chunks of dry ice into the bottle. Then using a funnel pour in the rice. The cap is placed on but not tightened so that the air in the bottle can escape as the dry ice sublimates and expands. Being heavier than the other gases in air, the carbon dioxide fills the bottle from the bottom and pushes the air out the top. It’s not perfect, for sure, and some air and oxygen remain inside, but the atmosphere in the bottle is mostly carbon dioxide and very low in oxygen so is very inhospitable to pests.

You need to watch the bottles and try to determine when the dry ice has completely sublimated so you can tighten the caps to prevent air from going back into the bottles. You can’t tell by looking at it because you can’t see the dry ice buried in the rice. So what I did was tighten the caps for a few moments and then look for signs of pressure building like some slight bulging of the bottle, then loosen the caps again and hear the gases escape. I checked like this now and then and at about two hours it seemed like the process was complete so I tightened the caps and stored them in a dark and relatively cool location.

Now comes an interesting effect. After the bottles have set for a few days a partial vacuum forms inside. Here is a picture of one of the bottles.

Rice storage usin dry ice

You can see that the top of the bottle is slightly deformed due to low pressure inside. When I first filled the bottle with rice there was a small airspace at the top. Now it has comletely shrunken and squeezed in the sides of the bottle. This seems odd and sort of counterintuitive. After all, the sublimated dry ice filled the container with cold carbon dioxide. After capping it tightly I would expect it to expand a bit as it warmed to room temperature. So what is going on here?

I found an answer offered on one website (unfortunately did not bookmark it and cannot find it now). A commenter on that site said she is a molecular biologist who does research involving absorbtion of gases and that she has observed that many grains slowly absorb carbon dioxide. She said that in a sealed contained containing carbon dioxide she would expect to see this effect of pressure reduction inside the container.

Cool! It’s cool because this gives a very visual indication that the container is still air tight and has not allowed any air to leak in. How long it will stay this way I don’t know but I will monitor it. If I get any containers that appear to have leaked then I will simply use those and replace them with new ones.

A couple weeks ago the Program for International Student Assessment (PISA) released its 2009 test results and many people in the U.S. were shocked at how poorly U.S. students performed against other countries. In reading, math and science the U.S. ranked well down the list between 20 and 30. Even more ominous is that Shanghai-China ranked first in all three categories. That’s the future of the world right there -the next generation of Chinese will dominate.

To be fair, the student population was obviously stacked to ensure the Chinese would have high scores. They tested only selected students from Shanghai which has the top education in China and is not representative at all of educational standards elsewhere. That is the Chinese way after all, complete fake in all ways – the way they faked the Olympics proceedings with pre-recorded footage of fireworks and lip-synching by the singer is a classic example of how fake China is to the core.

Nevertheless, U.S. students perform poorly compared to much of the rest of the world. And a new sign of just how poorly comes from a report that 25% of people who try to enter the military fail the entrance exam. Military leaders grow more concerned every day with their future ability to assemble a capable defense. Previously they warned that childhood obesity and early onset of diabetes represented a national security threat. Now they are concerned that 25% of applicants can’t answer simple questions like “If 2 plus x equals 4, what is the value of x?”