The previous day residue doesn't get crusty in a sealed bag. Not enough leftover in the bag to hardly notice. I guess you could rinse with an ounce of water or wipe out if worried about it. I've used the same bag for more than a week with no issue.I've heard of others doing this as well and I like the idea. You just use 1 mylar bag to eat out of the whole time? The food from the previous meal just stays in the bag and gets crusty until the next meal?