Even if the soup was thoroughly cooked and started out safe, bacteria from the air, utensils, or surfaces can find their way into the pot as it sits uncovered or partially covered. Over time, this can lead to contamination that isn’t always visible, smellable, or noticeable in taste—but can still cause foodborne illness.
So why do so many people, especially older generations, still follow this practice? In the past, refrigeration wasn’t always as accessible or as powerful as it is today. Letting food cool gradually overnight on the stove was sometimes the only practical option. And while many people did this without obvious consequences, it doesn’t mean the method was risk-free—it just means the risks weren’t always recognized.
