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Last Updated: Feb 6, 2017 - 2:32:04 PM |
 For as long as people have been eating food, people have also been searching for ways to make food more flavorful. Through the scientific observations of food we’ve come to understand different compounds that are naturally occurring in food and as humans do, people have tried to isolate them and create them artificially. Sometimes the results are great. Sometimes the results are not so great. Either way, the search for more flavor is on going.
One of the isolated compounds in food that is primarily responsible for foods flavor is Glutamic Acid. Glutamic acid (abbreviated as Glu or E) is one of the 20-22 proteinogenic amino acids, and its codons are GAA and GAG. It is a non-essential amino acid. The carboxylate anions and salts of glutamic acid are known as glutamates. In neuroscience, glutamate is an important neurotransmitter that plays a key role in long-term potentiation and is important for learning and memory.
Although they occur naturally in many foods, the flavor contributions made by glutamic acid and other amino acids were only scientifically identified early in the 20th century. The substance was discovered and identified in the year 1866, by the German chemist Karl Heinrich Leopold Ritthausen who treated wheat gluten (for which it was named) with sulfuric acid. In 1908, Japanese researcher Kikunae Ikeda of the Tokyo Imperial University identified brown crystals left behind after the evaporation of a large amount of kombu broth as glutamic acid. These crystals, when tasted, reproduced the ineffable but undeniable flavor he detected in many foods, most especially in seaweed. Professor Ikeda termed this flavor umami. He then patented a method of mass-producing a crystalline salt of glutamic acid, monosodium glutamate.
Glutamic acid, being a constituent of protein, is present in every food that contains protein, but it can only be tasted when it is present in an unbound form. Significant amounts of free glutamic acid are present in a wide variety of foods, including cheese and soy sauce, and is responsible for umami, one of the five basic tastes of the human sense of taste. Glutamic acid is often used as a food additive and flavor enhancer in the form of its salt, known as monosodium glutamate.
All meats, poultry, fish, eggs, dairy products, and kombu are excellent sources of glutamic acid. Some protein-rich plant foods also serve as sources. 30% to 35% of the protein in wheat is glutamic acid. 95% percent of the dietary glutamate is metabolized by intestinal cells in a first pass.
When glutamic acid or one of its salts is dissolved in aqueous solutions, a pH-dependent instantaneous chemical equilibrium of the amino acid's ionized forms will result. These ions are called glutamates. Salts exist only in a dry and crystallized form. The form ultimately responsible for the taste is the glutamate ion, and the form of glutamic acid at the time of the addition is not important. However, crystalline glutamic acid salts such as monosodium glutamate dissolve much better and faster than crystalline glutamic acid, a property important for use as a flavor enhancer.
Glutamic acid stimulates specific receptors located in taste buds such as the amino acid receptor T1R1/T1R3 or other glutamate receptors like the metabotropic receptors (mGluR4 and mGluR1) which induce the taste known as umami. The word umami comes from Japanese; it is also referred to as "savory" or "meaty".
Glutamate itself is a widespread amino acid. It is found naturally in all living cells, primarily in the bound form as part of proteins. Only a fraction of the glutamate in foods is in its "free" form, and only free glutamate can enhance the flavor of foods. Part of the flavor-enhancing effect of tomatoes, fermented soy products, yeast extracts, certain sharp cheeses, and fermented or hydrolyzed protein products (such as soy sauce and fermented bean paste) is due to the presence of free glutamate ions.
Japanese cuisine originally used broth made from kombu (kelp) to bring up the umami taste in soups. Manufacturers, such as Ajinomoto, use selected strains of Micrococcus glutamicus bacteria in a nutrient-rich medium. The bacteria are selected for their ability to excrete glutamic acid, which is then separated from the nutrient medium and processed into its sodium salt, monosodium glutamate.
In the Roman Empire glutamic acid was found in a sauce called garum, made from fermenting fish in saltwater. It was used so widely that it has been called the "ketchup" of the ancient Romans. The flavor enhancing properties of glutamic acid allowed Romans to reduce the use of expensive salt.
In April 1968, Robert Ho Man Kwok wrote a letter to the New England Journal of Medicine, coining the term "Chinese restaurant syndrome". In this letter he claimed:
“I have experienced a strange syndrome whenever I have eaten out in a Chinese restaurant, especially one that served northern Chinese food. The syndrome, which usually begins 15 to 20 minutes after I have eaten the first dish, lasts for about 2 hours, without hangover effect. The most prominent symptoms are numbness at the back of the neck, gradually radiating to both arms and the back, general weakness and palpitations...”
The syndrome is often abbreviated as CRS and also became known under the names "Chinese food syndrome" and "monosodium glutamate symptom complex."
Symptoms attributed to the Chinese restaurant syndrome are rather common and unspecific.
Although many people believe that monosodium glutamate (MSG) is the cause of these symptoms, an association has never been demonstrated under rigorously controlled conditions, even in studies with people who were convinced that they were sensitive to the compound. Adequately controlling for experimental bias includes a placebo-controlled double-blinded experimental design and the application in capsules because of the strong and unique after-taste of glutamates.
If our job as cooks and chefs is to simply make the most delicious food, and if glutamic acid makes food more delicious, why then isn’t everyone using MSG as a flavor enhancer? Well, it’s quite simple. Even though it has been rigorously tested and time and time again been proven completely safe for human consumption, the vilification of MSG persists today. The claims have been refuted. The science backs MSG. It’s a serious reminder of how claims made against someone or something can persist and last for generations even after the claims have been proven false.
Now that being said, I won’t be rushing out to buy MSG to season my food at Flying Fish. However, the science of fermentation has given me some interesting ideas for new experiments we will be taking on soon in the kitchen lab. If fermentation brings us more interesting flavor and complex flavor naturally without the addition of man made ingredients, you can bet we’ll be taking a serious look at it in our near future. Until then, you can simply grate some Parmesan cheese over your steak for the big umami burst of flavor you’re looking for without sprinkling MSG on your food. Until next time, remember there’s more to food than cooking and eating!
Tim Tibbitts is the
chef and owner of Flying Fish Modern Seafood in Freeport Bahamas. Flying Fish is the #1 rated restaurant in the
Bahamas on tripadvisor.com. You can see
what Flying Fish is all about at
www.flyingfishbahamas.com
or
www.facebook.com/flyingfishmodernseafood
and follow Tim on twitter @flyingfishfreep
© Copyright 2013 by thebahamasweekly.com
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