Strawberries do contain citric acid, as well as malic acid and ellagic acid. About 88 percent of the acid content in a strawberry comes from citric acid.
As a strawberry ripens, the ratio of sugar to acid changes; the acidity decreases, allowing the sweet taste of the sugar to prevail. Many fruits and vegetables contain citric acid. Citrus fruits tend to have higher concentrations of citric acid, which accounts for up to 8 percent of the dry weight of a lemon or a lime. Other berries contain citric acid, such as cranberries, raspberries and gooseberries. Lima beans, tomatoes and mangoes also contain citric acid.