Why do I need a special vacuum bag and cannot use a reguar plastic bag

For vacuum packaging special vacuum bags are required. The bags are coextruded with mostly a combination of polyethelene (PE) for strength, but also for sealability, and nylon (PA) as a barrier to prevent air from penetrating the bag over time. Good quality bags will maintain vacuum in the bag over a long period. The bags are often treaded so that the don’t stick together and processed in a clean environment. Special cook bags will allow the product to be heated in a water bath inside the bag.