Delicatessen meat and cooked food with a shelf life of more than 48 hours will definitely be added with delayed preservatives. It is recommended to bake them and eat them immediately. If you want to take them back to your hometown, buy them before leaving. There are several electric oven roast duck restaurants in Beijing. For takeout delivery, it will be delivered within an hour. Just call or order on the takeout platform before departure. For "Call a Duck", you can ask for vacuum sealing. There is no added preservative. You can eat it when you open it at home. The shelf life is 48 hours. Low temperature 72 hours