Flavor: The Science of Our Most Neglected Sense
Summary and excerpts
introduction
Beer and salted peanuts why? Salt inhibits bitter taste.
“All humans are flavor experts in the same sense that we’re face experts” Paul Breslin “it is literally a life or death matter. If you eat the wrong things, you’re dead.”
broccoli and tonic
Gary beauchamp monell former center director. He argues that losing taste is much worse than losing smell. It’s rare to lose the taste and thus we underestimate its impact. Cancer patients who lost taste due to the radiation sometimes starve themselves to death. “My view is that taste is absolutely the bedrock of flavor”
There may be multiple types of bitterness.
Why umami wasn’t recognized? Maybe because there is no pure umami. Also umami receptors max out quickly and we cannot sense strong umami. It’s always subtle. At the same time Asian culture has been recognizing umami.
Artificial sweeteners tend to have bitter aftertaste and have longer “duration” of the sensation
Salt is harder to replace. One interesting way is adding the flavor of foods that are usually very salty, like anchovy or bacon. De Kok and his team used bacon flavor to make sausages with 25% less salt.
Bitter taste receptors exist in our gut and even in our respiratory passages. They can detect bacteria communication. Some argued that bitter receptors may have evolved as a part of our immune system.
We sense important molecules by taste. But how about fat? We sense fat based on its texture but We may also have Receptors for fatty acids. Rick Mattes. “Oleogustus” however free fatty acids may taste awful–signals decay or rancidity.
Then there’s kokumi.
These basic tastes interact. Salt suppresses bitter. Sweet and bitter suppresses each other.
Super tasting ability (bitterness) doesn’t necessarily mean the person avoids the food. We can like bitter foods even if we are super sensitive about the bitterness.
beer from the bottle
Olfaction is much more complex than taste.
Linda Buck
Richard Doty
Shapists vs. vibrationists on how olfactory receptors recognize odor molecules.
Joel Mainland estimated 2.7 trillion candidate molecules and 27 billion of them have an odor.
One out of every twenty genes is for an odor receptor although more than half of them are “pseudogenes”. Because they are surface proteins, it is hard to figure out their shapes and corresponding odor molecules. Vast majority are “orphan” receptors. But many of them may not be for the odors but for chemical signals. They exist in all kinds of organs.
Odor is a synthetic sense. Each Combination creates an “odor object”. ~400 odor receptors can create a huge number of possible odor objects.
Gordon Shepherd. Smell is a pattern.
We are bad at describing and recognizing smells. Is it a fundamental limitation of human? Maybe not so because Jahai tribe in Thailand has more vocabularies for smells and they are better at recognizing smells consistently. Professional perfumers can do similar. But in the 80s, David Laing showed that people cannot really resolve more than 4-5 odor mixtures.
Andreas Keller. Mathematical approach to figure out how many dimensions we need to describe odor similarity.
Noam Sobel’s experiment on scent trail following shows that humans can track very well.
Matthias Laska’s animal experiment with odor threshold. Associate an odor with a reward. Humans are better than dogs in some chemicals.
Noam Sobel’s study: We tend to smell our hands more after handshakes.
Orthonasal vs retronasal olfaction.
Wysocki’s study on androstenone showed that genetics play a role in whether one can smell a compound or not but he also found that one can acquire the sense even if they didn’t have it initially. Gene also doesn’t explain much of cilantro preference (only about 9%).
the pursuit of pain
One of the flavor trinity is the sense of touch, which includes burning pain, temperature, and other sensations.
TRPV1: “hotness” receptor, TRPA1: “wasabi receptor”, TRPM8: menthol or eucalyptus (gum and mouthwash)
There are many different types of capsaicin. They differ in where, how long, etc.
Szechuan pepper induced unique tingling sensation. It’s about 50Hz buzz according to British researchers who used mechanical vibration to match. The ingredient is sanshool. It blocks potassium channel and induces neurons to fire randomly.
this is your brain on wine
House of Wolf by Caroline Hobkinson, with Charles Spence. Experimental course where the taste of food is modulated by other senses: can u hear the taste? Can u see the taste? …
Charles Spence did the Pringle’s crunch sound experiment.
Low pitch brings out bitter taste and high pitch brings out sweetness.
Gil Morrot found that adding red food coloring to white wine totally change enology student’s perception.
Our cognition is like a layer cake from raw sensation to high level cognition. But the high level cognition can also affect low level sensation.
People tend to prefer cheap wines when they don’t know the price. but if they know the price, even if it’s a fake, they prefer more expensive wine.
Feeding your hunger
Anthony Sclafani showed that even without sweet taste, rats can associate calorie (directly injected) and flavor. And the nutrient receptor is at the beginning of the small intestine.
This is called the flavor-nutrient conditioning. Dana Small studies this in human and showed that it happens largely unconsciously.
This learning process starts in the womb through amniotic fluid.
Flavor doesn’t really determine how much we eat and how we get fat. Even those who lost smell don’t get slim. GWAS shows no association between olfactory receptors and obesity.
Smell disorders are quite common and more prevalent in old people.