subject: Essential Citric Acid [print this page] Citric acid is a weak organic acid found in most fruits and vegetables, especially citrus fruits. It is also crucial in the Krebs cycle of human metabolism, involving the oxidation of fats, proteins and carbohydrates. The chemical is required by people to oxidize foods and produce energy.
History Of Applications
It wasn't until 1784 that citric acid was isolated and crystallized from lemon juice by Swedish chemist Carl Wilhelm Scheele. The effectiveness of it as a preservative became evident, so large-scale commercial production of it began in the late 19th century, especially by Italian citrus fruit growers. It was soon discovered that Penicillium mold could produce it from sugar, but it wasn't until 1917 that James Currie discovered that the mold, Aspergillus niger, was the most efficient producer.
Natural Sources
Foods naturally containing citric acid include citrus fruits. Lemons and limes, in particular, are rich sources. According to "Nutritional Sciences," this chemical can constitute up to 8 percent of the dry weight of these fruits. Berries, except for blueberries, also contain it, particularly strawberries, raspberries, gooseberries, and cranberries. Pineapples, cherries, tomatoes, some varieties of peppers, artichokes, and certain varieties of lettuce also contain the compound.
Uses
As an additive, citric acid preserves processed foods, giving them a longer shelf life. Traditionally, cheese is made by adding a bacterial culture to milk, allowing it to ferment slowly. In the making of cheese, it helps to ferment the milk faster, making it an essential part of large-scale cheese production. Commercially produced cheese uses the substance to speed up this process.
It is also a common ingredient in bathroom and kitchen cleaners. Even in dilute concentrations, such as 6 percent, citric acid can dissolve mineral buildup and rust from steel without the need for scrubbing. 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.
