What is Citric Acid?
Citric acid is a naturally occurring weak acid that can be commonly found in fruits and vegetables. It is an organic compound that has the chemical formula C₆H₈O₇. Citric acid contains 247 kcal of energy per 100 grams of solid. The salt of citric acid, citrate, is often found in other compounds such as sodium (trisodium) citrate.
Citric acid was first isolated by Carl Wilhelm Scheele, a german-swedish chemist, in 1784 through drying and processing lemon juice to form citric acid crystals. However, it was not until 1890 where citric acid was produced at an industrial scale.
Sources and Manufacturing
Most citric acid manufactured today comes from commercial processes with more than two million tons produced annually. The process of creating citric acid comes from the fermentation of sugars by the Aspergillus niger mold. From these resulting processes, the Aspergillus niger is filtered from the solution and through a subsequent chemical reaction, involving the use of bases and acids, citric acid crystals are formed and ready for use.
Qualities
As mentioned previously, citric acid is a weak acid and has a pH that ranges between 3 to 6 depending on the citric acid concentration in the solution. Because of its acidic nature, citric acid imparts a citrus-like sour flavor. These properties have been heavily leveraged in the food industry as 50% of the world’s use of citric acid is as an acidity regulator in beverages. Acidity regulators play an important role in preventing microbial growth and maintaining/extending shelf life by decreasing the pH to create an environment unsuitable for microbial growth, but safe for human consumption. Acidity regulators are different from acidulants (typically weak acids), which impart a tart, sour, or acidic flavor. Thus, depending on the amount used in a product, citric acid can play a role as either an acidity regulator, acidulant, or both.
Other Uses
About 20% of the citric acid produced worldwide is used in non-liquid food production, 20% in cleaners, and 10% in other consumer products and industrial processes. In solid and semi-solid foods, citric acid is used to create a tart or citrus flavor, acting a replacement to using lemon or lime, in addition to acting as a natural preservative. Citric acid can also be used as a surfactant in ice cream or products with high fat and water content to prevent separation of the fats from water and ensure the stability of the product over time.
In industrial processes, citric acid can be used as a clean agent. Citric acid makes for an effective clean agent as it acts as a strong chelating agent allowing it to bind to and solubilize metals. This makes it particularly effective at removing limescale, hard water, and rust from surfaces. Other uses of citric acid are in consumer products such as in cosmetics for chemical skin peels, facial cleansers, etc. The salts of citric acid such as sodium citrate can be used as a method to deliver sodium to the bloodstream, when ingested, but also a blood pH regulator when delivered directly into the bloodstream to control metabolic acidosis. Alkali citrate can also be used to help to treat and control the formation of kidney stones.
Biologically, citric acid is found as an intermediate in cell metabolism, specifically the citric acid cycle or the Krebs/TCA cycle. Specifically, acetyl-CoA or oxaloacetate is metabolized into citrate before being further metabolized into isocitrate. Citrate also acts as an inhibitor of phosphofructokinase (PFK), a key glycolytic enzyme, such that when citrate concentrations are high and in abundance, slows the activity of PFK effectively signaling to the cell to reduce glycolytic flux to reduce the precursors of citrate.
Citric acid in Carbs Fuel Products
The presence of citric acid plays one or both roles as an acidity regulator or an acidulant in the Carbs Fuel product line. For example, in the Carbs Fuel Original gel citric acid acts as an acidity regulator to create an environment that prevents microbial growth and ensures stability for a two year shelf life. Citric acid also acts as an acidulant to impart a light citrus flavor to enhance and create a pleasant flavor profile. The Carbs Fuel Sport Drink Mix also utilizes this flavor profile of citric acid to balance the sweetness profile and to encourage hydration during exercise.
