Technically speaking, a desiccant is anything that absorbs water or maintains dryness around it. Possibly the most common type is a silica gel desiccant. Because of its high surface area silica gel is usually in the shape of small beads. Those small beads are typically kept in small paper packages when used in food storage.
Silica itself is also known as silicon dioxide. Some desiccants have added cobalt chloride. When this chemical is combined with water it turns from blue to purple, and eventually with enough water absorption it turns pink. Some products use a different chemical that changes from orange to green as it gets more and more filled with water. This is a very helpful indicator to show when the gel has absorbed the most water it can and needs to be changed out. Or, in some cases it can be dried out and used again. If the gel is heated to temperatures above 250 degrees Fahrenheit for at least two hours the gel will be dried out and ready to be reused. Be sure to check with the manufacturer’s instructions, though, to ensure safety and quality of the product.
Even though it is a chemical, it is generally not dangerous, particularly when used in its current forms. That is why it is ideal for food and pill storage. Exposure to moisture can degrade the quality of food products whether by making them less crispy in the case of salty snacks, or by allowing mold to grow on them. Many pill bottles also contain these moisture absorbing silica gel desiccants to keep them in their best usable condition for the consumer. This is helpful for storage on the shelves at a store or for use in the private home to keep opened bottles and bags fresh and safe. Some products are not packaged for use with food, so be sure to check the labels for your intended use.
Silica gel is a popular desiccant for a wide range of uses because it is relatively inexpensive. It is certainly less expensive than replacing ruined products that have been damaged or destroyed due to water exposure. It is one of the most effective products of its kind. Although some other items are available that do similar work, this gel is the most efficient. It absorbs even as much as 40% of its weight in water. This makes it long lasting and very successful in humidity protection. The popularity of the product is not unwarranted. It is easy to use, safe, convenient and extremely helpful.