Natural vs. Artificial Production of MSG and Sensory Perception

MSG (monosodium glutamate) is the sodium salt of one of the most commonly occurring amino acids, glutamic acid. This non-essential amino acid is naturally synthesized in the human body and in many high-protein foods, tomatoes, cheese, and mushrooms, creating the umami flavor described as savory and meaty (Glutamate, 2022). Although glutamic acid is abundant and safe, its counterpart MSG, an isolated and concentrated form, has gained a controversial reputation after a series of reactions in the American public during the 1960’s known as the Chinese Restaurant Syndrome. To understand more about its controversy, we must first, ask what is MSG? How is it different from natural glutamic acid? And why do so many love its signature flavor?

Figure 1. Chemical structures of glutamic acid, monosodium glutamate, and glutamate (Simpson, 2023). 

Mushroom's Natural Production of Glutamic Acid vs. MSG (Production and Flavor):

To understand the differences between natural glutamic acid and MSG, it is important to understand their production processes. Glutamic acid is an amino acid created by the breakdown of a protein. This process can be seen in mushrooms, where glutamic acid is a natural byproduct of their protein metabolism. Additionally, mushrooms’ umami flavor can be further enhanced through fermentation, which breaks down even more proteins to increase the amount of glutamic acid. Similarly, artificially produced MSG is created through the fermentation of various foods like starch, sugar beets, sugarcane, or molasses through the bacterium Corynebacterium glutamicum. The free glutamic acid is then separated, extracted, and then neutralized using sodium hydroxide or sodium carbonate to create its salt form. While both sources yield glutamic acid, the key to MSG’s intense umami flavor lies in how it delivers free glutamate in its most readily available form (Berg, 2019).

What Gives MSG its flavor?:

Umami flavor is received through umami receptors on the tongue. The glutamate binds to these receptors which are distributed throughout the tongue. When MSG is consumed, it dissociates into sodium and glutamate in the mouth. The free glutamate, which is identical in structure to that found naturally in mushrooms and cheese, activates the umami receptors, triggering a distinct savory feeling. Unlike glutamic acid still bound within proteins – how it is normally found in food – which must be broken down during digestion, MSG delivers glutamate in its active form (Vandenbeuch & Kinnaman, 2016). This instant delivery is what gives MSG its signature intensity and why it is such a powerful flavor enhancer. 

Figure 2. Flavor receptors in the tongue (Silberner, 2024).

Key Takeaways

MSG, the most concentrated form of umami flavor, is unique because it instantly delivers glutamate to the tongue’s receptors. MSG is a favorite in the food industry and is used in a variety of foods around the world. Still, the stigma around it has led to bans and limitations of its use around the world. While some studies, individuals, and media claim it has adverse effects on health, most studies have come to the conclusion that current research is not adequate to come to a verdict about its health properties, and that more detailed research is needed (Zanfirescu et. al, 2019). While its artificial production and incorporation into manufactured goods is contested, its natural production from everyday foods like mushrooms and cheese make its abundance a true wonder of food science.

References

1. Dr. Eric Berg DC. (2019, October 20). MSG vs Glutamate: What’s the Difference? [Video recording]. https://www.youtube.com/watch?v=BKTqXqD6dZ4

2. Freeman, M. (2006). Reconsidering the effects of monosodium glutamate: A literature review. Journal of the American Academy of Nurse Practitioners, 18(10), 482–486. https://doi.org/10.1111/j.1745-7599.2006.00160.x

3. Glutamate: What It Is & Function. (2022, April 25). Cleveland Clinic. https://my.clevelandclinic.org/health/articles/22839-glutamate

4. Mantzioris, E. (2024, September 9). MSG is back. Is the idea it’s bad for us just a myth or food science? The Conversation. https://doi.org/10.64628/AA.akft7ykkd

5. Silberner, J. (2024, May 29). The Textbooks Were Wrong About How Your Tongue Works—The New York Times. The New York Times. https://www.nytimes.com/2024/05/29/science/taste-buds-tongue-map.html

6. Simpson, M. (2023, July 16). MSG — one of the largest food myths being pushed. Skeptical Raptor. https://www.skepticalraptor.com/skepticalraptorblog.php/msg-myth-one-of-the-most-persistent-in-the-pseudoscience-of-food/

7. Vandenbeuch, A., & Kinnamon, S. C. (2016). Glutamate: Tastant and Neuromodulator in Taste Buds123. Advances in Nutrition, 7(4), 823S-827S. https://doi.org/10.3945/an.115.011304

8. Zanfirescu, A., Ungurianu, A., Tsatsakis, A. M., Nițulescu, G. M., Kouretas, D., Veskoukis, A., Tsoukalas, D., Engin, A. B., Aschner, M., & Margină, D. (2019). A review of the alleged health hazards of monosodium glutamate. Comprehensive Reviews in Food Science and Food Safety, 18(4), 1111–1134. https://doi.org/10.1111/1541-4337.12448

Thumbnail image: (Mantzioris, 2024)