It certainly does sound mysterious that these innocent-looking fine, white crystals with no really distinctive taste of their own should be able to boost the inherent flavors of such a wide variety of foods.
The mystery lies not in whether MSG really works, nobody doubts that, but in how it works. As is the case with so many ancient, stumbled-upon practices, a lack of scientific understanding hasn’t stopped people from enjoying the benefits of MSG for more than two thousand years.
What makes MSG’s reputation as a flavor enhancer so hard to swallow is that the terminology is somewhat misleading. Flavor enhancers don’t enhance the flavors of foods in the sense of improving them; that is, they don’t necessarily make things taste better. What they seem to be doing is intensifying, or magnifying, certain flavors that are already present. The food processing industry likes to call them potentiators; I call them flavor boosters.
At this point, I’m obliged to acknowledge the debate about its effects on sensitive individuals.
Everyone has heard of Chinese Restaurant Syndrome or CRS, an unfortunate and politically incorrect label that was applied in 1968 to a diffuse collection of symptoms, including headaches and burning sensations, reported by some people after consuming their selections from column A and column B. The culprit behind CRS appeared to be MSG, which is short for its chemical name, monosodium glutamate (gluTAMate). And thus began a thirty-year battle over its safety.
In one corner sits the National Organization Mobilized to Stop Glutamate, whose uncomplicated solution to the problem is expressed in its acronym. According to NOMSG, glutamates in their many guises (see below) are responsible for at least twenty-three afflictions, from runny noses and bags under the eyes to panic attacks and partial paralysis.
In the other three corners, predictably, are the manufacturers of prepared foods, who find MSG and similar compounds to be enormously valuable in enhancing the consumer appeal of their products.
The official referee is the FDA who, after many years of evaluating data, remains convinced that “MSG and related substances are safe food ingredients for most people when eaten at customary levels.” The trouble is that all people are not “most people,” and the FDA is still struggling to regulate the labeling of glutamate-containing foods so as to be most useful to all consumers.
Monosodium glutamate was first isolated from kombu seaweed by a Japanese chemist in 1908. The Japanese call it aji-no-moto, which means “essence of taste” or “at the origin of flavor.” Today, 200,000 tons of pure MSG is produced every year in fifteen countries. It is sold by the carload to manufacturers of prepared foods and by the ounce to consumers as Ac’cent and Zest.
Monosodium glutamate is a salt of glutamic acid, one of the most common amino acids that proteins are made of. The flavor-boosting properties reside in the glutamate part of the molecule, so any compound that releases free glutamate can perform the same trick. The monosodium version is merely the most concentrated and convenient form of glutamate.
Parmesan cheese, tomatoes, mushrooms, and seaweed are rich sources of free glutamate. That’s why a little bit of any of these ingredients can give a big boost to the flavor of a dish. The Japanese have traditionally made use of seaweed’s glutamate in subtle, delicate soups.
Our sense of taste involves some very complex chemical and physiological reactions. Exactly how glutamates fit in has been hard to pin down. But there are a couple of ideas that have been kicking around.
It is known that different-tasting flavor molecules stick to the receptors in our taste buds for different lengths of time before detaching. One possibility, then, is that glutamates make certain molecules stick around longer, and therefore taste stronger. Also, it is probable that glutamates have their own distinct set of taste receptors, separate from the receptors for the traditionally quoted quartet of sweet, sour, salty, and bitter. To further complicate matters, quite a few substances other than glutamates have “flavor enhancing” properties.
The Japanese long ago invented a word to describe the unique effects of seaweed’s glutamates on taste: umami. Today, umami is acknowledged to represent a separate family of savory tastes that are stimulated by glutamates, similar to the family of sweet tastes that are stimulated by sugar, aspartame, and their saccharine relatives.
Many proteins contain glutamic acid, which can be broken down into free glutamate in several ways, including bacterial fermentation and our own digestion. (There are about four pounds of glutamate in the proteins of the human body.) The chemical breakdown reaction is called hydrolysis, so any time you see “hydrolyzed protein” of any kind, vegetable, soy, or yeast, on a food label, it probably contains free glutamate. Hydrolyzed proteins are the most widely used flavor boosters in prepared foods.
While a food product may not contain MSG as such and may even say “No MSG” on the label, it may well contain other glutamates. So if you suspect that you are one of the small number of people who are hypersensitive to glutamates, watch also for these euphemisms on the labels of soups, vegetables, and snacks: hydrolyzed vegetable protein, autolyzed yeast protein, yeast extract, yeast nutrient, and natural flavor or flavoring.
What’s a “natural flavor,” you ask? It’s a substance derived from something in Nature, rather than made from scratch in a laboratory or factory. To be called “natural,” it doesn’t matter how chemically complex or convoluted the processes may be that ultimately isolated the flavor substance, as long as those processes began with something untouched by human hands.
As The U.S. Code of Federal Regulations 101.22(a)(3) puts it: “The term natural flavor or natural flavoring means the essential oil, oleoresin, essence or extractive, protein hydrolysate, distillate, or any product of roasting, heating or enzymolysis, which contains the flavoring constituents derived from a spice, fruit or fruit juice, vegetable or vegetable juice, edible yeast, herb, bark, bud, root, leaf or similar plant material, meat, seafood, poultry, eggs, dairy products, or fermentation products thereof, whose significant function in food is flavoring rather than nutritional. Natural flavors include the natural essence or extractives obtained from plants listed in Secs. 182.10, 182.20, 182.40, and 182.50 and part 184 of this chapter, and the substances listed in Sec. 172.510 of this chapter.”