MSG (monosodium glutamate) is the king of artificial flavor enhancers. The amino acid glutamate was first isolated in 1908 by Tokyo Imperial University Professor Kikunae Ikeda, who derived the substance from dried kelp, the same kombu used to make traditional Japanese stock [source: Turner]. Ikeda is credited with the discovery of the "fifth taste," umami, translated from Japanese as "savory" or simply "delicious."
A year later, the Japanese company Ajinomoto developed MSG, a powdered form of glutamate with the added kick of sodium. MSG is used as a flavor-enhancer throughout East Asian cuisine. Japanese, Chinese and Thai food is generously seasoned with MSG to make the savory flavors in brothy noodle and meat dishes soar.
Outside of its pure powdered form, MSG is also the active ingredient in some of the world's most popular jarred sauces, seasoning blends and condiments: like Maggi seasoning sauce in Mexico and India, Kewpie mayonnaise in Japan, and Accent seasoning in the U.S., which is actually pure MSG [source: Moskin].
In America, MSG is often treated as a four-letter word, closely associated with outbreaks of so-called "Chinese restaurant syndrome" – bouts of headaches and dizziness caused by eating Chinese food laced with MSG [source: Moskin]. While research has shown that decreased consumption of MSG can lower the risk of headaches, there is no direct association between eating MSG and feeling sick [source: Xiong et al.]. Otherwise, large potions of Asia and Latin America would have a constant headache.
To avoid having the nasty letters "MSG" on their labels, American food processors use other glutamate-rich additives like yeast extracts, hydrolyzed proteins and anything with the word whey [source: Moskin].
For its part, Ajinomoto didn't stop with the invention of MSG. The Japanese company has developed a full line of umami-enhancing amino acids for the food industry. There are low-sodium versions of MSG like monopotassium glutamate (MAG) and monoammomium glutamate (MPG) and another family of compounds called free nucleotides.
Two popular free nucleotides sold by Ajinomoto are IMP (disodium inosinate) and GMP (disodium guanylate). Both exist in nature and work in tandem with the amino acid glutamate to boost the umami flavors in food up to 30-fold [source: Souza]. There's IMP in cheese, for example, that pairs with the glutamate in ground beef to up the umami ante of cheeseburgers. Synthetic IMP and GMP are just as powerful when teamed with MSG. No surprise they are the two final ingredients on the back of that bag of Nacho Cheese Doritos.