Fruits that contain high amounts of acid include sour apples, oranges, lemons, limes and tangerines. Some other acidic fruits include raspberries, strawberries, blackberries, blueberries and cranberries. Sour pineapples, plums, grapefruits and grapes also contain significant amounts of acid.
Low-acid fruits include figs, Asian pears, melons, bananas, dates and papaya. Ripe pineapples, persimmons, gooseberries, mangos and elderberries also contain small amounts of acid.
To be considered acidic, fruits must have a pH level of 4.6 or lower. Acid in fruits detoxifies the human body and strengthens the immune system. Acidic fruits also improve skin and hair condition. However, the acid in fruits can cause allergies and rashes, so a balanced diet should include fruits with both high and low acid content. Acidic fruits can also cause negative effects during some illnesses, such as the flu. Some high-acid fruits can cause acidic reflux.
Most vegetables are low in acid, including asparagus, broccoli, cucumbers, beans and corn. Garlic, onions, peas and peppers are low in acid as well.
Most canned and pickled vegetables have a high acid content, even if the fruits and vegetables themselves are low-acid. This is because the acid is added in order to prevent dangerous bacteria growth in foods.