as observed in a 2012 Journal of Applied Sciences and Environmental Management study, citric acid has a synergistic effect on other antioxidants that together help increase oxidative stability while decreasing free radical concentrations, which are known to cause cell damage or death;
despite being a weak acid, citric acid is an effective alkalizer as it is able to break down built up mineral compounds in the body that, in some cases, can cause painful conditions such as kidney stones, which citric acid prevents;
since it has a natural affinity for minerals and metals, citric acid decreases the time it takes for these compounds to be absorbed into the body;
Food and Beverage:
citric acid is a preservative that in the form of lemon juice has been used for countless products in the food and beverage industry;
mostly used as a flavouring agent worldwide, citric acid is sour and that is exactly what teas, juices and soft drinks want in order to balance out their overall taste;
uses as an emulsifying agent, citric acid is effective in preventing fat separation within ice cream
Pharmaceutical and Cosmetics:
antiviral tissues have citric acid as one of their key ingredients, which can be greatly beneficial for combatting sickness during flu season;
can adjust pH values for both creams and gels, which without the use of citric acid will be less operational as well as possibly having an unpleasant aroma;
facial skin-enhancing products like the chemical peel have citric acid as one of their active ingredients
eliminating both wax and colouring from the hair is possible with citric acid as an active ingredient in common shampoos;
soaps and laundry detergents are more effective with citric acid being able to soften water and as a result allow the cleaning compounds to form productive foams
Within its molecular structure, citric acid has three carboxyl groups and for this reason it has three dissociation stages as well (and 3 pKa values). Considered a weak acid, citric acid can be found naturally in citrus fruits like lemons, limes and oranges. It is also naturally found in humans as its conjugate base, citrate, is the well-known intermediate that serves as a key component in the Krebs (or citric acid) cycle, which is what all aerobic organisms use in order to yield energy. In its anhydrous form, citric acid is crystallized from a source of hot water, while the opposite can be said for its monohydrate form (cold water). These two forms of citric acid exist as white, hygroscopic (water-holding and –attracting) crystalline powder in room temperature. Citric acid is categorized as a bulk chemical as approximately two millions tonnes of it is produced on an annual basis and used for various industries on a global scale.
In 1784, the Swedish pharmaceutical chemist, Carl Wilhelm Scheele, was the first known scientist to isolate citric acid from lemon juice. Producing citric acid through fermentation, however, wasn’t discovered until 1893, when it was found that Penicillium mould in conjunction with sugar yielded the weak acid. Less than three decades later, American food chemist James Currie discovered a more efficient citric acid producer in the Aspergillus niger mould, which led pharmaceutical company, Pfizer, to initiate macro-scale production. Slight deviations of this proven technique are still used today with a carbohydrate-based medium of either sucrose or glucose.