Why is my Puppy Chow taste stale and chewy?

As the humidity rises the cereal will absorb moisture. Also the sugar will attract more moisture. Refrigerating it will slow down the absorption of moisture.

The cereal is also absorbing moisture from the melted chocolate.

You can try refrigerating it now but there is no way to crisp up or dry out the cereal as any heat applied to it will melt the coating.

I was thinking I have never had a problem with puppy chow getting stale and chewy, but I do keep it in a covered bowl or zip loc bag. But I can't remember a time that I made it that it lasted more than 24 hours with 3 adults and 3 kids in the house.

This snack gets stale FAST. I keep mine in an air-tight container and refrigerating it can help, too.

Make sure you're keeping it refrigerated and in an air tight container, I keep mine in zip-lock bags.

I prefer Milk Bone Dog Biscuits. The keep longer and taste great!

Yes. You really should let your puppy make that decision.

that is just what cereal does when it is exposed to air.