Umami has only recently been accepted as our fifth taste, although cooks and food companies have been exploiting it for years.
Not only do umami-imparting ingredients add a delicious, savory, yummy taste to foods, they also enhance other tastes, so that other ingredients, such as salt and fat, can be minimized.
And, as if that weren't enough, umami ingredients can be made from natural, healthful sources, such as soy, seaweed, asparagus, and tomatoes.
Cruise the Internet, though, and these same ingredients are referred to as "silent killers"; many websites decry their use and blame them for everything from Alzheimer's to obesity.
The Food and Drug Administration designated the ingredients as safe decades ago, but the agency continues to receive reports of adverse effects.
Taste versus Flavor First, we need a basic understanding of taste sensory mechanisms.
Have you ever accidentally picked up someone else's drink or taken a bite of food, thinking it was something else? You may like the accidentally ingested item perfectly well, but find yourself sputtering, because the taste is so different from what you expected.
Knowledge of this process sets the stage for designing products that exploit the complex chain of events involved in taste perception, for example in designing reduced-salt products that still taste salty, or in sweet tasting products with lower sugar.
Part of tasting is in the expectation, and a major part of flavor is imparted by smell.
Hold your nose and you lose a lot of flavor, but can still perceive the basic tastes.
Salt still tastes salty and lemon juice still tastes sour.
Salty, sweet, bitter, sour, and umami compose our current list of tastes.
Other flavors have been described as tastes in other cultures.
Some involve texture, temperature or other sensations, such as metallic, minty, fatty, spicy or astringent.
To be considered a taste, rather than a flavor, however, requires a dedicated sensing mechanism.
How We Taste The thousands of taste buds in our mouths each contain hundreds of cells, including sensory receptor cells and nerves.
Each taste bud carries receptors for different tastes, although some appear to be more sensitive to one taste than another.
The receptors for salty and sour tastes involve ion channels, while sweetness, bitterness and umami involve the binding of specific molecules to receptors.
Sodium ion channels are involved in the perception of saltiness, and sourness or acidity is perceived through hydrogen ion channels.
The perception of sweetness requires the activation of two separate glucose-binding receptors.
Umami involves the binding of various free (not bound in proteins) amino acids, including glutamate, to their receptor.
The taste-stimulating molecules may also result in increased sensitivity of other receptors.
In Japanese, èsF- Means Umami Many non-Western cultures have words similar to umami for describing a delicious, rich, extra taste present in some foods.
Umami-rich foods require less salt and less fat.
Many French recipes increase umami with the addition of veal stock.
The Japanese use a seaweed-based broth, dashi, to add flavor to many dishes, and it was investigating the cause of this that led the Japanese chemist, Kitunae Ikeda, to isolate and identify glutamate as the source of this extra flavor 100 years ago.
Free amino acids, those not bound in proteins, add the unique, delicious taste and mouth feel called umami.
The free amino-acid content of foods increases during aging, fermentation, ripening, or heat exposure.
Adding anchovies, meat stocks, fish sauce, and fish flakes impart umami taste to foods.
Soy products, especially fermented soy sauce, asparagus, ripe tomatoes, seaweed, mushrooms and green tea are among the many vegetable sources.
Red wine and aged parmesan cheese are also high in free glutamate, and some yeast extracts have a high umami factor.
What Is Glutamate Glutamate, one of the 20 basic amino acids that make up proteins, is the anion form of glutamic acid and a nonessential amino acid because the body can make its own.
(MSG is the monosodium salt of glutamic acid.
) Glutamate functions in the body as a neurotransmitter and is involved in many major biochemical processes.
It may play a role in learning and memory.
Extracellular glutamate is normally removed by transporter molecules, but some diseases or damage may cause glutamate to build up outside cells, causing problems associated with autism, Alzheimer's, strokes, and epilepsy.
Commercial fermentation processes produce 99 percent pure glutamic acid, which is labeled MSG.
The bacteria in the process introduce some D-glutamic acid.
Our bodies produce and use L-glutamic acid/glutamate.
Other manufacturing processes, such as the breakdown of protein products into their constituent amino acids, form a number of products with less than 99 percent glutamic acid These are labeled with other names, including "hydrolyzed proteins" and "processed flavors.
" All forms of MSG and other free amino acid products, including aspartame, have been accused of having toxic effects.
The MSG Controversy Despite having classified MSG as generally recognized as safe (GRAS) in the late 1950s, the FDA continues to receive reports of MSG-related adverse effects.
A 2003 article in FDA Consumer Magazine reported that these concerns led to a number of studies over the years, which found MSG safe when used at typical levels.
Continued complaints have led to other studies and reports, which acknowledge that some people, especially those with asthma, or those consuming over 3 grams (a "typical" serving contains 0.
5g) may experience short-term reactions, but that there wasn't any evidence of long-term effects.
The short-term effects can involve numbness, burning sensation, tingling, facial pressure or tightness, chest pain, headache, nausea, rapid heartbeat, drowsiness, and weakness.
Asthmatics may experience these symptoms as well as difficulty in breathing.
Additional studies in asthmatics under controlled conditions have not produced consistent results.
Because the complaints continued, a Consensus Meeting was held in Stuttgart, Germany, in 2006, to summarize recent data and evaluate the safety of glutamate salts.
The invited experts concluded that a maximum intake of 16mg/kg is safe, but called for further research on the effects of high MSG doses in the presence of impaired blood brain barrier function.
Many Diseases Associated with MSG All sorts of diseases from diabetes and obesity-related complaints, to migraines, asthma, retinal damage, neurological problems, birth defects, and learning disabilities have been attributed to the consumption of MSG and other free glutamate-containing foods.
Many websites warn consumers to avoid free glutamate-containing food additives, and test kits are being developed to detect their presence in foods.
However, a review of 40 years of literature on the effects of free glutamate shows contradictions, and more importantly did not turn up any placebo-controlled trials showing a consistent effect from MSG consumption.
Some studies show that MSG can induce obesity, diabetes, retinal degeneration and neurotoxic effects in rodents, but many of these studies involve injection rather than ingestion, with many involving higher dosages than one would normally consume.
Government reports claim that MSG is safe, in typical doses.
Yet, The FDA requires labeling products that have free amino acid products added, acknowledging that some people do have problems after its consumption.
Websites abound with dire warnings, denigrating MSG and associated compounds as poisons, citing anecdotal "evidence" of health conditions attributed to MSG and related compounds.
Pat Robertson hosted a three part series last year on the "silent killer" and declared that MSG is "worse than drugs or alcohol," blaming it for the obesity epidemic, among many other things.
The perception of food safety is more important to most people than the perception of good taste.
Until the public is reassured as to the safety of free amino acids, we will continue to see an increasing number of MSG-free products on the shelves of our supermarkets.