I want to buy a vacuum sealer for food. The vacuum bags do not have a hechsher. Normally, I buy ziplock bags that are OU. To keep this general, I am hoping someone can elaborate on the reason and ruling behind needing approval for food storage containers. If the food is always room temperature or colder when putting into the bag, does that make a difference? I imagine the law is based on the transfer of taste from the bag, which seems to imply the food going into the bag is warm, because otherwise the transfer would not occur.
After looking at star-k's list of items that don't need approval, which includes plastic bags, I wonder why OU feels they do need approval.