Citric acid and ascorbic acid are two similar substances that occur naturally in fruits and vegetables, especially citrus fruits such as lemons and limes. Both acids have nutritional benefits, and they're commonly used in food manufacturing and as a preservative, but there are several differences between the two compounds, including a variation in flavor.
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Intro to Ascorbic Acid
Ascorbic acid is the chemical name for vitamin C. Your body needs vitamin C for tissue growth, repair and wound healing. It’s also an antioxidant, which helps to protect cells from substances that damage DNA. According to the National Institutes of Health, the recommended dietary allowance for vitamin C is 75 milligrams for adult women and 90 milligrams for men. Smokers require an additional 35 milligrams each day. Vitamin C is a water-soluble and heat-sensitive vitamin, so it's not stored in the body, and much of it can be destroyed when foods are heated or canned. Ascorbic acid can be added back to foods to enhance or replace vitamin C that is lost during the cooking process.
Citric Acid 101
Citric acid also has antioxidant properties, but it’s not a vitamin or an essential nutrient like ascorbic acid. Instead, it acts as an acid buffer and can help to regulate acidity in the body. When consumed from foods or beverages, it can be helpful in treating kidney stones or preventing them from forming. If you need to increase your citric acid intake, the best sources, according to a 2008 study in the "Journal of Endourology," are lemon, lime, grapefruit and orange juice, as well as lemonade. Citric acid is also sometimes combined with certain minerals like calcium and magnesium, or with medications, because it allows your body to absorb them better.
Use as Preservatives
Because of their antioxidant properties, both ascorbic and citric acid can help to remove oxygen during food manufacturing and storage, and they are often used to preserve a food’s freshness and flavor. Citric acid is the more commonly used preservative because it’s more inexpensive and readily available in large commercial quantities. It also lowers the pH of foods and beverages, which helps to prevent growth of bacteria and microbes. Ascorbic acid does a better job of preserving the natural color of certain foods, especially fruits, vegetables and even meats that turn brown when cut open and are exposed to oxygen.
While both compounds are frequently used in food processing, there are flavor differences that can affect which food products they are used with. Ascorbic acid has a more bitter, acidic flavor, while citric acid has a more tart and sour flavor, so it’s often preferred to enhance the flavor of foods like beverages, desserts, candies and even medicines.