The DryCard™ is an inexpensive device developed by UC Davis researchers for determining if dried food is at a low enough moisture content to prevent mold growth during storage. Moldy food has a bad taste and may be contaminated with harmful toxins. Molds will not grow if the air around a product is lower than 65 percent relative humidity.
DryCard shows dryness with color guide
How can you check if something is dry? The indicator strip on the DryCard turns blue or grey when food is adequately dried, or pink if food product is too wet for safe storage.