Sous vide is long waterbath at around 55 C or lower. Not a typical plastic safety issue temperature. Cooking in plastic (or any "original package") has a food

Sous vide is long waterbath at around 55 C or lower. Not a typical plastic safety issue temperature. Cooking in plastic (or any "original package") has a food safety point in restaurants. Keeping it sealed until the outside is sterilized reduces possible contamination. Immersion also makes for easier and faster heating.