Citric Acid

What is Citric Acid?

Citric Acid, or “sour salt,” is a weak, organic acid naturally found in citrus fruits. It is most often used as a natural preservative or to add an acidic or sour taste to food and baked products.

It can also be used as an emulsifying agent. For example, it is added to some ice creams to keep fats from separating. It is sold commercially as white, powdery substance.

Origin

The first records of this acid are found in the eighth century. However, Carl Wilhelm Scheele first isolated it from lemon juice in 1784. Industrial production took off during the late 19th century. Then in 1893, sugar was discovered as a way to process citric acid. American food chemist James Currie began using mold to produce it in 1917.

Commercial Production

The molecular formula for citric acid is C₆H₈O₇. Traditionally it is derived from fruits such as lemons and limes and makes up to 8 percent of the dry mass of some citrus fruits. Citric acid plays a part of the metabolism of most living things, yet in much smaller quantities.

For commercial uses today, citric acid is generally created from feeding sugar to black mold. The most commonly used mold is “Aspergillus niger.” Sucrose or glucose, usually from corn starch, is added to the black mold. This creates a solution, which is filtered out of the mold. The solution is then processed using lime and sulfuric acid. Black mold is a cheap and efficient way to make citric acid on a large scale, processable way. ¹

Some consumers are pushing back against the more chemical process used to make citric acid, and say GMO products are often used in the production, but not labeled. In response, some companies have started producing GMO-free versions.

Application

Citric acid can be used to replace liquid lemon juice or vinegar in recipes to add a sourness. It can easily mix into liquids and will decompose when heated above 174^oCelsius or 345.2^oFahrenheit. It can enhance the flavor in a citrus-based recipe.

A few shakes of the “sour salt” adds a strong flavor to frostings or glazes. Another popular application is adding it to sourdough or rye breads for a touch of tang. Bread products usually only need a teaspoon or less.²

Store it in a dry, cool place without exposure to moisture. Smaller packets are helpful in helping retain flavor.

FDA Regulation

There are no limitations or sanctions on citric acid and it is recognized by the FDA as GRAS. It is classified as a preservative or additive.
 

References

1. Żyła, K. (1990). “Acid phosphatases purified from industrial waste mycelium of aspergillus niger used to produce citric acid. Acta Biotechnol.’ 10: 319–327. doi: 10.1002/abio.370100402
2. Salim-Ur-Rehman, Alistair Paterson, and John R. Piggott. “Flavour in Sourdough Breads: A Review.” Trends in Food Science & Technology 17.10 (2006): 557-66. Web.