Increase shelf life of marshmallows

Looking through your writeup,
I can only detect two things that might be responsible for early spoilage.

  1. ‘aW’ Which is water activity as @Roy have rightly said. When moisture is too much in a food product, it is liable to earlier spoilage. You can try to reduce the water been incorporated in your product.

  2. Choice of packaging material,

Packaging materials play a very major role when preserving an already processed food product.

  1. the nature of the packaging material
  2. Presence of Air inside the package material
  3. storage Room