If you’d prepare to use Tupperware containers to store your frozen food, that’s completely up to you. Tupperware boxes are airtight containers, so they’re a safe way to store food. However, Tupperware containers are typically bulky, meaning that they take up a lot of space in your freezer compared to bags. You might also prefer to save your Tupperware for taking your lunch to work or generally transporting food items away from home, which storage bags are less suitable for.