Citrus fruits are one of the best sources for Vitamin C, also known as ascorbic acid. Although this acid can be beneficial to the body, people sometimes have problems with acidic foods. People with sensitive stomachs may have trouble digesting foods high in acid. Further, acids can break down tooth enamel, which can lead to tooth decay. Understanding the acidity levels of citrus fruits is helpful in avoiding these issues.
Many may not realize there are actually two different acids at work in most citrus fruits. Ascorbic acid is the same as vitamin C. The other type of acid is known as citric acid. The difference between the two is that, structurally, citric acid has an extra oxygen molecule. Citric acid contains no vitamin C.
Identifying the fruit with the highest acidity levels was the focus of a study done at and published by Michigan State University. That study found lemons had the highest pH, at 2.75. Limes had a pH of 2.88, and grapefruit came in next with a level of 3.65. Oranges were the least acidic, with a pH of 4.35. On the pH scale, the lower the number, the more acidic it is. Neutral water has a pH of 7.
The acids in citrus provide benefits. The most well-known benefit of ascorbic acid is the strength it provides for the human immune system. Vitamin C is considered essential to fighting off infection. Though citric acid does not have Vitamin C, it is responsible for giving citrus its distinct tangy flavor.
The acidity levels in citrus fruits are not constant and can be affected by many different factors, including weather, soil pH and fertilizer used. A study by the Florida Department of Citrus found that, from the mid-20th century to the late 20th century, the acid levels in orange juice had decreased by more than 25 percent. In addition to weather and fertilizer, the location of the groves and their rootstocks also likely played a role.
The acidity levels in citrus fruit may not be a major source of concern for most people. Still, for those who suffer from digestive problems or have severe dental problems, keeping away from high-acid foods may be a big help. Further, it may explain while drinking orange juice may not be a problem but eating a grapefruit of eating products with lemon may be.