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Before I investigated food processing science, I used to think that citric acid was from citrus fruit. Silly me. I envisioned the food preparer squeezing the fresh lemony zing into my food. Apparently this is not economical or scalable, so here is how citric acid is really manufactured. Erase the lemon image.
Citric acid production uses the mold Aspergillus niger, which produces citric acid from sugar. Pfizer began industrial production using this mold in 1929. The sources of the sugar for this process have changed over time. In almost all production of citric acid, GMO corn is used in the form of hydrolyzed corn starch and steep corn liquor. The corn is soaked in water with sulphur dioxide to remove the corn kernel and the liquor is what’s used in the citric acid processing.
Many have asked why I have citric acid on my list of ingredients to avoid. The sources of sugar – hydrolyzed corn starch and corn steep liquor also contain free glutamic acid because the corn protein is completely degraded in this process. The production process precipitates citric acid and glutamic acid, as well as other acidic amino acids. These contaminants are not purified away and so are components of the ingredient labeled as “citric acid”. The citric acid ingredient, therefore, contributes to the free glutamate level in foods.