While these strips are not food grade, and say do not let them come in contact with your foods, you can lay a muffin paper or paper towel square over your food in the jar, put the strip on top, close your jar, and test the humidity. I don't do this as a normal means of storage. I will, occasionally, use it on something like dense fruit if I want to put it back for storage, such as apricots or pineapple chunks. But it is definitely NOT something you need to incorporate into your routine of dehydrating.