I wanted to copy a Wine Spectator article I just read but no luck, so I searched the web to find something to read. Kikunae Ikeda isolate Umami in 1907 (he aslo developed MSG)Jonayjan Pratt has dedicated a restaurant (Umami Cafe) in Croton on the hudson and Tim Hanni (who I studied with) is a big backer.
What are your thoughts?
Isolating the fifth element of taste
Discovery of the mechanism behind the mysterious fifth taste, umami, is changing our perception of perception itself.
By Thomas Maeder
February 9, 2001
Everyone knows that there are four basic tastes: sweet, sour, salty, and bitter. Wrong. A fifth taste -- umami -- was admitted last year to the gustatory pantheon, and a growing awareness of its role in the flavor and pleasurable sensations of food is changing the way food processors, nutritionists, and chefs think about what they do. The artful use of umami can make mediocre fare taste better, and good food taste great.
In 1907, the Japanese scientist Kikunae Ikeda sat before a bowl of tofu in dashi, a kelp-based broth, and pondered dashi's peculiar flavor and its puzzling ability, like salt, to enhance or harmonize the flavor of other foods. Curiosity drove Mr. Ikeda to the laboratory bench, where he found that the substance responsible for umami, as he named it, was glutamic acid, one of the 20 common amino acids of which proteins are built.
PASS THE UMAMI, PLEASE
"An attentive taster," Mr. Ikeda told an American audience at the 8th International Congress of Applied Chemistry in 1912, "will find something common in the complicated taste of asparagus, tomatoes, cheese, and meat, which is quite peculiar and cannot be classed under any of the [other known tastes]." It is often faint, he said, usually overshadowed by other, stronger tastes, and may easily pass unnoticed. "Had we nothing sweeter than carrots or milk, our idea of the quality 'sweet' would be just as indistinct as it is ... with the peculiar quality."
Glutamate that is bound within proteins does not produce an umami taste, only the free form, which is liberated when proteins break down during processes like aging, fermentation, ripening, or cooking. Glutamic acid, however, tastes sour as well as umami, so Mr. Ikeda experimented with other glutamate compounds, finally settling on its sodium salt: monosodium glutamate, or MSG. He approached S. Suzuki & Company, one of Japan's largest pharmaceutical companies at the time, with a proposal to market his compound as a flavor enhancer. In 1909, the company began selling what it called Aji-no-moto, a product so successful that the company subsequently renamed itself Ajinomoto. In 1917, it came to the United States under the brand name Super Seasoning.
Why should the umami taste exist? One theory holds that tastes guide us toward healthy food choices -- bitter and sour help us avoid dangerous substances, like toxic alkaloids, while sweet and salt attract us to sources of needed energy, sodium, and chloride. Because glutamic acid is the most abundant amino acid in animal protein, umami perception could be a meat-protein-seeking mechanism. This theory is hard to prove, but it is suggestive that carnivores and omnivores, like rodents, respond positively to umami, while herbivores are indifferent or even repelled.
The umami story was complicated by the discovery that another class of molecules, 5'-ribonucleotides, also produces umami taste. These compounds, commercially available in the form of disodium 5'-inosinate (IMP) and disodium 5'-guanylate (GMP) are effective at far lower concentrations than glutamate. More significantly, they have such a strong synergistic interaction with glutamate that very small quantities of IMP or GMP added to MSG or to foods that naturally contain free glutamate yield an intense umami taste.
JUST A PINCH
For many years, taste physiologists debated whether umami was a genuine fifth distinct taste or merely a combination of others, perhaps sweet and salt. "But if you block salt taste and take pure MSG," says Gary Beauchamp, director and president of the Monell Chemical Senses Center in Philadelphia, which has done extensive research on umami, "you get an incredible umami taste. Block sweet and salt and give umami, and you taste umami. It's clearly something different."
The clearest proof that something is a basic taste would be the discovery of a receptor that responds specifically to the stimulus. The receptors for sour and saltiness are well understood. Controversy lingers about bitter, and there appear to be multiple sweetness mechanisms.
Early last year, Nirupa Chaudhari and Stephen Roper at the University of Miami cloned a specific glutamate receptor from rat tongue, which is generally accepted as the definitive proof of umami's basic taste status. It does not, however, respond to the 5'-ribonucleotides, meaning that other receptors and complex interconnections are at play.
Moreover, a receptor is not the whole story. The flavor-enhancing effect of umami is one feature that makes it difficult to define. MSG alone is not pleasant, though it brings out deliciousness in foods. This is not unique to MSG: salt, as well as being salty, is also a flavor enhancer. Cocoa has a bitter edge that adding more sugar will not correct, but a pinch of salt brings up the sweetness and dampens the bitterness, a useful but poorly understood phenomenon that takes place at the neural level.
The discovery of a receptor does, nonetheless, have significant practical implications. "Our work would probably make it easier for companies to screen thousands of compounds. You can't throw thousands of compounds at a human tongue, whereas you can at a molecule," says Dr. Chaudhari. "You can set up automated, nonsubjective screening methods. You could do this for bitter as well -- not only how do you produce bitter, but how do you mask it, which would be useful in medicines as well as in foods."
Mr. Beauchamp of Monell refers to such mechanized taste-testing -- called high-throughput screening, in the biotech business -- as "the Holy Grail of the food flavor industry." Umami, he adds, is a particularly interesting target. "There's no question that industry is interested in finding the parallel to a sugar substitute. They'd like to find something that gives the umami taste without being MSG." MSG has a bad reputation because of its alleged association with Chinese restaurant syndrome (see "Clean Bill of Health").
In December 2000, a new biotech company called Senomyx, located in La Jolla, California, signed a research collaboration agreement with Kraft Foods to explore new flavorings. Using a variation on the combinatorial chemistry and high-throughput assay techniques now employed to screen new drug candidates, Senomyx will test huge numbers of compounds against taste and smell receptor molecules, conspicuous among them the umami glutamate receptor.
"You can't just sit down with a 96- or 384-well microtiter plate and taste or smell things one after another," says Paul Grayson, the Senomyx CEO. "After about the fifth one, you can't remember the first one. With this sort of automated screening we can optimize other characteristics as well, such as volatility for olfactory compounds, or looking at systemic absorption of flavorings."
Automated assays can also be used in a reciprocal way, as a more efficient way of isolating new receptors. By testing all the expressed proteins in taste tissue and teasing out those that show activity when exposed, for example, to MSG, IMP, or GMP, researchers may discern more components of the taste pathways.
Oddly, until recently, awareness of umami was greater among scientists than in the kitchen. Tim Hanni, a wine master and founder of WineQuest, a company dedicated to the enjoyment of wine, finds that knowledge of the balance and interactions between the five tastes helped him to escape traditional notions of what wines go with which foods, as well as to understand and better control food combinations themselves. One of the most important objectives in making good food is to maximize umami. "How do you explain umami to someone who doesn't know what it is?" he says. "Sometimes it's easier to show what it isn't. Tofu is not umami. So you put it in soy sauce. Rice is very low in umami, but if you cook it in stock where you transfer the soluble compounds from chicken you've got a more delicious and nutritious product. The umami taste of potatoes increases 11-fold when they're cooked, but that's still not enough, so you add sour cream, bacon, cheese."
In addition to making foods taste better, umami can be used to encourage healthy eating. The elderly progressively lose their sense of taste and smell and therefore often stop eating well. Many diseases and drugs alter these senses as well. Susan Schiffman, of the department of psychiatry at Duke University Medical Center, uses various flavors and MSG -- or IMP and GMP when low sodium is desired -- to improve the diets of old people and patients. By selectively flavoring nutritious foods like vegetables, Ms. Schiffman says, you can alter the mix of foods that people choose to eat. If you want to give an older person food with a meatier taste, she adds, "you dump in some IMP or GMP, and then they say, 'Now that you're here, they're serving better soup.'"
The home page of the Monell Chemical Senses Center, with information on taste, smell, and current research at the center.
Randy's World article on umami taste and its relationship to wine.
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