Storing food in a plastic bag inside an aluminum foil container is generally safe, provided the plastic is food-grade and free of harmful chemicals like BPA. Ensure the plastic bag is not in direct contact with the aluminum foil, as certain types of plastic can react with aluminum. Keep the container sealed to prevent contamination and maintain freshness. However, for long-term storage, especially in the freezer, consider using airtight, BPA-free containers to avoid potential issues with plastic degradation and to better preserve the quality of the food.