Flavor is much more complex than just taste. Flavor can be collected, extracted, infused, created and transformed. And, in a billion-dollar flavor industry devoted to putting flavors into processed foods, fermentation is the oldest and most natural flavor creator, developing new flavors at a molecular level.
“Fermentation as a flavor creation process in collaboration with microbes, there’s almost no limit to how you can apply it and use the ingredients around you and have a more flavorful palette to work from,” says Arielle Johnson, PhD, a flavor scientist, gastronomy and innovation researcher and co-founder of the Noma Fermentation Lab.
A food chemist dubbed the flavor whisperer, she works with restaurants on innovating dishes and cocktails. She researches how flavor is perceived and is writing a book on her studies, Flavorama. Her work comes together in “all things science and cuisine have to say to each other.”
This week Johnson shared her insights into flavor and fermentation as a guest lecturer at Harvard University’s Science & Cooking series.
Taste & Smell Receptors
Flavor can be quite complex – Johnson calls it a black box.
There are five primary tastes: sweet, sour, salty, umami and bitter. Each taste evolved to ensure humans get basic nutrition. We use sweet foods for the energy in sugar, sour ones for vitamin C from fruit and fermented foods. Salty foods provide the essential mineral sodium. We seek umami foods for the taste of glutamine, an amino acid in proteins and fermented foods.
But bitter, Johnson points out, doesn’t sense one thing. It senses multiple molecules that are potential toxins for us. This is why bitter is called an acquired taste.
Smell is Johnson’s favorite part of the flavor profile. In order to taste, we must smell, too. Molecules land in the olfactory receptors in the nasal cavity and help activate taste. This is why food is tasteless if you plug your nose while eating. But the back of the throat is also connected to the nasal cavity, so the throat becomes “the secret backdoor” for sensing flavor.
While there are five major tastes and four receptor areas on the tongue, there are 40 billion smellable molecules and 400 receptors for smell.
Supertasters vs. Nontasters
Taste and smell, she detailed, help us understand how fermentation works.
The population can be divided into supertasters or nontasters. During her presentation, Johnson had the audience put a strip of filter paper on their tongue. The paper included a harmless bitter molecule phenylthiourea (PTC), but only roughly half the class could taste it. This group are supertasters – the group who could not taste the PTC are nontasters.
She explained everyone has different density of their taste buds. Supertasters have more taste buds, so more taste receptors signals are sent to their brains. This has culinary implications. Because their sense of taste is more sensitive, flavors are intense and supertasters have a less adventurous palette. Meanwhile nontasters have dulled senses, so it takes a lot of flavor to activate taste.
“The good news for supertasters is that fermentation is usually salty and sour and often umami – all of which counteract bitterness,” Johnson says. “Fermentation is a way to create new flavors but also transform ingredients.”
Fermentation as Flavor
Though “microbes are opportunistic” and pop up in foods whether planned or not, fermentation can’t be forced, Johnson says. When making a sauerkraut, for example, microbes don’t need to be added. Fermentation works with what’s on the surface of the cabbage and on the producer’s hands.
Salt is key in fermentation as a flavor additive, a preservation element and a safety measure. Salt filters out bad molds and avoids letting a ferment spoil. Other factors “dial in the flavors in this molecular flavor creation process,” she says, like the correct ingredients, temperature control and humidity.
“We’re really excited about microbes and fermentation,” Johnson says. “In this process of this exponential growth that microbes do, they’re eating things, they’re getting energy, but they’re also running their regulator metabolism. So there’s all these waste products that are not very significant to the microbes, but that can create a lot of interesting flavor complexity.”