How Flavor Enhancers Function

A slice of juicy watermelon is the ultimate summertime treat—refreshing, light, and the perfect balance of sweet. Next time you enjoy a watermelon, try an unexpected twist: sprinkle a slice with a pinch of salt. Salty watermelon may sound odd, but instead of tasting salty, it will bring out the sweetness like never before.

Taste is one of the most elusive senses to understand. There's no single organ or chemical receptor in the human body dedicated solely to identifying the molecules and compounds in foods and translating them into distinct flavors. Yet, our bodies and brains work together to instantly distinguish salty from sweet, bitter from sour, and pleasant from unpleasant.

Despite our limited understanding of the chemistry behind taste, we do know that certain naturally occurring substances and chemical additives have a mysterious ability to boost food flavors. Salt is the ultimate flavor enhancer. For over 10,000 years, humans have used salt in food, initially as a preservative, but also because it has the remarkable power to turn even the most bitter vegetables and strong meats into something delicious [source: Henney et al.].

Glutamate is another naturally occurring substance thought to give foods like seaweed, mushrooms, and Parmesan cheese their savory and almost meaty flavor. In the early 20th century, Japanese researchers isolated pure glutamate and combined it with sodium’s salty boost to create one of the most powerful and debated flavor enhancers: monosodium glutamate, or MSG.

We all consume flavor enhancers daily, often in surprising quantities. They're added to our favorite processed foods, restaurant dishes, and snacks to elevate the sweet and savory notes while masking the bitterness of chemicals. Nacho Cheese Doritos, one of the world’s most irresistible snacks, not only have loads of MSG, but also seven other glutamate-rich ingredients like Romano cheese, onion powder, and garlic powder. And, of course, plenty of salt [source: Souza].

Even the most health-conscious cooks know that a few twists of salt, a splash of soy sauce, or a spoonful of glutamate-rich Maggi sauce can be the key to turning a bland health meal into something worth finishing. But what’s behind this transformation?

Join us as we delve into the science of taste and uncover how a mix of natural compounds and controversial chemicals can deceive our brains into craving more!

The Science Behind Taste

Why do we have the ability to taste? Like our other senses, our sense of taste developed over millennia, shaped by environmental pressures. Just as humans evolved sharp vision to detect predators or spot potential mates, our sense of taste has two fundamental purposes: to keep us alive and healthy enough to reproduce.

The taste buds on our tongues are equipped with specialized taste receptor cells that connect through nerve pathways directly to the brainstem [source: Henney et al.]. When we eat, these cells analyze the molecules in the food, categorizing them into five distinct tastes: salty, sweet, sour, bitter, and umami (savory).

When our ancient ancestors wandered through forests and across grasslands in search of food, a sensitive sense of taste could mean the difference between life and death. Bitter-tasting leaves might be poisonous. A salty flavor often indicated the presence of vital minerals. And sweetness pointed to glucose, the essential fuel for the brain.

But our sense of taste goes beyond just the tongue. The flavors we perceive come from a combination of several complex processes. The odors of food, not just their direct 'taste,' play a crucial role in how we experience flavor. (Try holding your nose while eating a jelly bean—you’ll likely miss the flavor entirely.) These odors travel up the back of the throat into the nasal cavity, activating smell receptors. How food tastes is also shaped by our personal experiences, including what we ate as children or even what our mothers consumed while pregnant [source: Beckman].

Flavor enhancers interact with both the evolutionary and emotional aspects of taste. For instance, sodium and glutamate are essential for cellular processes. Our bodies require a certain daily amount of these minerals and amino acids for survival, which helps explain why we've developed not only the ability to detect salty and savory flavors but also why we find them so appealing.

But what causes these substances to enhance or change the way we perceive other foods? Take salt, for example. It not only makes chocolate taste sweeter but can also somehow make canned soup feel 'thicker.' Scientists are just beginning to uncover how salt can block the detection of bitter compounds, allowing a food's natural sweetness or savory flavor to shine through. As for the 'thick' sensation in soup, salt may stimulate 'touch' neural systems that send mixed signals to the brain [source: Henney et al.].

Natural Flavor Boosters

Salt is the quintessential natural flavor enhancer. The salt shaker you find on diner tables or in your kitchen holds table salt, which is produced through solution mining: injecting water into underground salt deposits and evaporating the brine to form crystals. Meanwhile, 'sea salt' is harvested by the sun from ocean water or salty lakes [source: Maldon Salt].

For at least 5,000 to 10,000 years, salt has been mined, traded, and consumed in massive quantities. It was the first known preservative, essential for curing meats and fermenting vegetables. Ancient humans likely consumed between 3,000 to 5,000 milligrams of sodium daily, almost entirely from salt [source: Henney et al.].

This consumption pattern isn't far from modern habits; in 2013, the average American consumed about 3,400 milligrams of sodium per day, although the recommended daily intake for adults is 2,300 milligrams [source: Mayo Clinic].

No other flavor enhancer compares to salt. Research shows that the taste of processed foods improves directly with more salt, up to a certain point. (Food scientists are certainly aware of this threshold.) Salt is believed to reduce the body's sensitivity to naturally bitter compounds like caffeine, magnesium sulfate, and potassium chloride [source: Henney et al.]. This explains why sweet dishes taste sweeter and savory ones richer when salt is added.

MSG, a synthetic umami booster, is a powerhouse of glutamate, but there are many natural sources of glutamic acid. In Japan, kombu, a type of sea kelp, is used to make stocks rich in glutamate. Other glutamate-packed ingredients include shiitake mushrooms, Parmesan cheese, anchovies, tomatoes, dried shrimp, and egg yolks, all of which are commonly used by chefs and home cooks worldwide to enhance the savory depth of dishes [sources: Moskin, Turner].

Home cooks seeking a healthier, natural way to amplify the flavors of meals can rely on traditional kitchen tricks. Fresh herbs added to finished dishes – like parsley in pasta or cilantro in taco fillings – provide layers of flavor without the need for extra salt. A splash of vinegar or a squeeze of lemon or lime can also brighten up fish or stew in much the same way as salt does [source: Clower].

Artificial Flavor Enhancers

MSG (monosodium glutamate) is the reigning champion of artificial flavor boosters. The amino acid glutamate was first isolated in 1908 by Professor Kikunae Ikeda of Tokyo Imperial University, who extracted it from dried kelp, also known as kombu, which is traditionally used in Japanese stock [source: Turner]. Ikeda is credited with discovering the "fifth taste," known as umami, meaning "savory" or simply "delicious."

In 1909, the Japanese company Ajinomoto developed MSG, a powdered form of glutamate enhanced with sodium. MSG has become a staple flavor enhancer in East Asian cooking. It is generously added to Japanese, Chinese, and Thai dishes, making the savory notes in brothy noodle soups and meat dishes more intense and satisfying.

Outside of its pure powdered form, MSG also plays a key role in some of the most beloved sauces, seasoning mixes, and condiments worldwide: for instance, Maggi seasoning sauce in Mexico and India, Kewpie mayonnaise in Japan, and Accent seasoning in the U.S., which is essentially pure MSG [source: Moskin].

In the United States, MSG is often treated with suspicion, being linked to the so-called "Chinese restaurant syndrome"—symptoms like headaches and dizziness after consuming Chinese food laced with MSG [source: Moskin]. Although research suggests that reducing MSG consumption can alleviate headaches, no direct link has been proven between MSG and sickness [source: Xiong et al.]. If this were the case, large parts of Asia and Latin America would be plagued by constant headaches.

To avoid the controversial label of "MSG" on their products, American food manufacturers rely on other glutamate-rich ingredients such as yeast extracts, hydrolyzed proteins, and anything containing whey [source: Moskin].

Ajinomoto, the company behind MSG, didn't stop at just creating monosodium glutamate. The Japanese firm has expanded its offerings, developing a wide range of umami-boosting amino acids for the food industry. These include low-sodium alternatives like monopotassium glutamate (MAG) and monoammonium glutamate (MPG), as well as a series of compounds known as free nucleotides.

Among the popular free nucleotides produced by Ajinomoto are IMP (disodium inosinate) and GMP (disodium guanylate). Both occur naturally and enhance the savory umami flavor by working alongside glutamate, amplifying flavors by up to 30 times [source: Souza]. For instance, IMP found in cheese complements glutamate in ground beef, enhancing the umami in a cheeseburger. Synthetic IMP and GMP are equally potent when paired with MSG, which explains why they often appear as the final ingredients in products like Nacho Cheese Doritos.