One of the best ways to preserve food is by drying: freeze dried foods, dried beans, dried rice, and many other items all keep very well. The lack of moisture inhibits the growth of bacteria that would spoil the food. But stored dried food needs to be kept dry on a continuous basis. One easy way to ensure this is by including a packet of silica gel in each container of stored food. So, for example, if you have your food stored in 5 gallon containers, you would want to use at least one 10-gram silica gel packet per container. But silica gel packets are somewhat pricey. So this prepping and survival post is about keeping stored food dry, using possible substitutes for silica gel to absorb water.
For the experiment, I used 4 sealed containers, each with 100 grams of water and 100 grams of one of four different desiccants: silica gel, salt, dry rice, dry beans. The containers were left sealed for one week. This results in 100% humidity for the entire week, to test the maximum absorption of the desiccant. At the end of 7 days, the containers were opened and the desiccants were weighed. Any weight over 100 grams indicated water absorbed by the desiccant.
The results:
100 g silica absorbed 30 grams of water 100 g beans absorbed 4 grams of water 100 g rice absorbed 4 grams of water 100 g salt absorbed 6 grams of water
Silica gel was 5 times more efficient at absorbing water than salt, and 7.5 time more efficient than rice or beans. However, these other desiccants did absorb a significant amount of water, and they are each more readily available and less expensive than silica gel.
Next, I did an analysis based on cost:
silica: 100 g silica absorbed 30 grams of water 10 Silica Gel Packets of 10 Grams Each $8.69 per 100 g $0.29 per gram of absorbed water
dry beans: 100 g beans absorbed 4 grams of water $1.08/lb (454 g) $0.24 per 100 g $0.06 per gram of absorbed water
rice: 100 g rice absorbed 4 grams of water $5.44/10 lb (4540) $0.12 per 100 g $0.03 per gram of absorbed water
salt: 100 g salt absorbed 6 grams of water $0.50/lb (454) g $0.11 per 100 g $0.02 per gram of absorbed water
Each 10-gram silica packet absorbed about 3 grams of water. It takes 50 grams of salt to absorb the same amount of water. But that salt costs less than one tenth the price, in terms of cost per gram of absorbed water.
In some cases, it is more convenient to use a packet or two of silica gel than 50 to 100 grams of salt. You can just throw the packet in the 5-gallon bucket with any dried food. But if you run out of silica gel or you are on a tight budget, you might want to consider using salt. You can put the salt in a coffee filter, and tie it closed with a twist-tie, or you can put the salt in the bottom of the container (as long as the salt won’t mix with any loose food, like rice).
– Thoreau
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