Citric acid occurs naturally in fruits and vegetables, and serves as a natural preservative and flavoring in foods and drinks. Citric acid is also crucial in the Krebs cycle of human metabolism, involving the oxidation of fats, proteins and carbohydrates. Foods with citric acid can be found in the orchard, garden, and in your local grocery store. It is also widely used in cleaning products, air fresheners, candles, hand sanitizers, and personal-care products.
Naturally Containing Citric Acid
Foods naturally containing citric acid include citrus fruits; lemons, oranges, and limes have particularly high concentrations, at up to 8% citric acid by weight. Berries, except for blueberries, also contain citric acid, particularly strawberries, raspberries, gooseberries, and cranberries. Pineapples, cherries, tomatoes, some varieties of peppers, artichokes, and certain varieties of lettuce also contain citric acid.
As an Additive
As an additive, citric acid preserves processed foods, giving them a longer shelf life. In the making of cheese, citric acid helps to ferment the milk faster, making it an essential part of large-scale cheese production. Traditionally, cheese is made by adding a bacterial culture to milk, allowing it to ferment slowly. Commercially produced cheese uses citric acid to speed up this process. Soft drinks, particularly fruit-flavored varieties, contain citric acid added as a preservative and as a flavoring.
Less-expensive frozen treats use citric acid as a fat emulsifier, to keep the added vegetable fats from separating in ice cream, sherbet, and sorbet. When added to sodium bicarbonate, it prompts an effervescent action in candy and powdered drinks, as well as powders and tablets for indigestion.
Acids found in grapes used for wine include tartaric, malic, and citric acid. These add to a vintage's total acidity, and influence the color, balance, and taste of the wine. These acids also influence the growth of yeasts during the fermentation process, and limiting bacterial growth. Most of the citric acid found in inexpensive, commercially distributed wine is the result of fermenting sucrose solutions added after the fermentation process.
Asian foods often contain lemon and lime juice, which contains citric acid. Indian foods often have tamarind, a fruit which contains citric acid. Chinese recipes usually do not use citrus fruits and citric acid additives, except for lemon chicken and various sweet-and-sour recipes containing pineapple, orange, and lemon. Mediterranean food may include tomatoes, lemon juice, lime juice, pineapple, and other more exotic fruits. Middle Eastern food usually does not contain citrus fruits; however, hummus can be made with or without lemon juice. American food abounds with naturally occurring citric acid, and citric acid as an additive in relishes, ketchup, mayonnaise, desserts, and main courses.