Some customers have asked “do I need to heat seal stand-up pouches even though they have zippers?” We answer that question with “yes.” We say this for two reasons.
First, the zipper does not provide a complete barrier to oxygen. When a zipper locks together, it will prevent particles from passing through it and large amounts of air flow, but molecules of oxygen can still pass through. Oxygen will penetrate through the zipper and degrade many products.
Second, the pouches need to be sealed for food safety and tamper evidence.