If unsweetened coffee is kept in the refrigerator all night, the key issue depends on its freshness, and the taste of freshly ground coffee is destroyed; If there is sugar or milk in freshly ground coffee, but you don't drink it immediately after you buy it, or even drink it every other night, the problem will become bigger.
Low temperature storage:
During the roasting process, coffee will produce sugar, natural soluble substances and oil, and at the same time, it will retain a small part of water to help water extract the flavor of coffee. High temperature and direct sunlight will upset this balance. Stay away from objects with strong odor, because coffee absorbs odor easily. Don't put coffee in the refrigerator, it will cause the water in the coffee to condense and dilute the essence of coffee.