Why lemons are sour?

The sour taste of lemons is due to the presence of citric acid, which is a natural organic acid found in citrus fruits. Citric acid is a weak acid that has a sour taste and can be used as a preservative. It is also responsible for the tart flavor of many fruits and vegetables.

The amount of citric acid in lemons can vary depending on the variety of lemon and the stage of ripeness. Generally, lemons that are not fully ripe will have a higher concentration of citric acid and will be more sour than those that are fully ripe.

Citric acid is also found in other citrus fruits, such as oranges, grapefruits, and limes. However, the concentration of citric acid is generally higher in lemons than in other citrus fruits, which is why lemons are known for their sour taste.