Results
Our experiment showed:
We tested the environmental humidity to make sure our humidity loggers were working and the experimental conditions matched the previous group. The environmental humidity reached 90% over the course of 12 hours. We can assume the humidity was 90% and higher during the rest of our experiment.
Our data collection of the flour bags lasted a week with the bags being opened daily for 30 minutes. As a result, the flour control bag (no desiccant) had ~50% humidity. The flour 1 desiccant bag had ~35-40% humidity. The flour 2 desiccant bag had ~30-35% humidity. This data showed that the 2 desiccant bag had a better humidity absorbance than the 1 desiccant bag.
There is a graphical comparison between the desiccants used in previous trials. Silica gel had higher humidity levels than calcium chloride; however, silica gel packets are desiccant for our communities.
1 Silica Gel Packet (Blue) vs No Silica Gel Packet (Green)
This image depicts the humidity by percentage of the bags of flour with one silica gel packet in one bag and no gel packet in the other. As we mentioned earlier, after over 160 hours the 1 silica gel packet kept the humidity between 35-40% which was about 15% lower than the bag with no dessicant!
2 Silica Gel Packets
Unfortunately we only had two working data loggers at a time so we had to take seperate data for the bag with 2 silica gel packets after we completed the first test. What we found was that in over a weeks time 2 silica gel packets were able to reduce the humidity to around 30% and keep it there. While this test and the first test weren't on the same timeline, every other factor was held constant so the data can be compared and we can see that two Silica Gel packets were slighly more effective.
Last Year Group's Data
Last year for their food preservation project, the group did similar testing to what we did but they used Calcium Chloride as their dessicant instead. This test was done over a much shorter time period, but as you can see, Calcium Chloride was highly effective in reducing the humidity in the bag. When comparing this data with our data, you can clearly understand that Calcium Chloride is the more effective dessicant being that it held the humidity between 15-20% although there are other factors benefiting silica gel such as reusability and less risk of spillage into the food.
Silica Gel versus 100% humidity
A second test that our group decided to do was for one hour each day we went into the lab and opened the flour bags in a giant sealed glove bag. We did this each day to see the effect the dessicant would have when it was faced with 100% humidity. Unfortunately after about two days of testing both of the data loggers completely stopped working. We would recommend future groups to test this hypothesis, along with other tests presented in the "Future Plans" page.