It depends on what kind of food it is. Rice, beans, flour, etc. You can buy it for one month at a time and keep it properly. For meat, it should be frozen for about a week, and it does not rule out that some are strongly frozen, and more than half a month will do. Vegetables can be preserved for 2~7 days. According to different preservation methods, some vegetables can also be preserved for a long time, but the taste will be obviously different. In summer, it is best to shop fresh on the same day. For these purchases, just find a good food partner in the early stage and let him send it there. It takes so much time to go to the vegetable market.