Tastebuds over time?

Tastebuds in the news! NPR ran a story yesterday that children’s love of sweet things might be based in their biology.  We all know that our tastes change over time, kids who refuse to eat anything green or spicy can grow up to love Thai green curry.  Our palates expand with time and exposure to new things. Kids are notorious for a dislike of bitter flavors, making an icky face after a sip of coffee or beer (that they begged to try!) But, new research shows that it’s not just exposure or cultural diet that causes our tastes to change as we age, children around the world show strong preferences for really sweet foods.

Researchers from the Monell Center in Philadelphia shows that humans are born with a much higher preference for sweet tastes, that fades when we approach adolescence.  This might be because sweet foods are high in easily digestible calories, that young children need for rapid growth.  NPR also cited research that shows that our desire for sweet foods decreases drastically in adolescence. When our bones finish growing, sweet preferences quickly decrease to adult levels.

Our sense of taste also changes with advanced age.  Although maybe not as obvious as deteriorating hearing or sight, we start losing taste buds in middle age.  Sweet and salty tastes frequently decrease in sensitivity more than sour or bitter tastes.  However, for many people, the effects are mimimal.

About 2 million people in the US have an impaired sense of smell. Permanent or temporary, this condition, called anosmia, can seriously affect people’s ability to enjoy foods. A friend of mine with anosmia occasionally catches certain smells, but misses many others.  She never notices when something is burning on the stove, or if someone just farted. However, she appreciates more complex flavors in food than just sour or salty.  Talking with her about it reminds you just how complex and connected our senses really are.

We might take our ability to taste or smell for granted, but people who have suddenly lost these senses often report a serious sense of disconnectedness with the world around them.  In Remembering Smell, Bonnie Blodgett describes losing her sense of smell and how it changed her perceptions of the world.  We use these senses subconsciously and constantly, so I look forward to reading more research on the roles these senses play in physiology, evolution, cognition, and culture.

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Taste Tests

I really like the taste of beer.  And so do many other people.  But “beer” obviously isn’t just one flavor, they vary in complexity from watery Natural Light to a complex craft-brewed Stout. There is such a variety of tastes that make up beers that the taste of beer can be hard to explain. Luckily, yesterday, at a beer tasting at the Wisconsin Science Festival, we learned how the sense we call “taste” really works.  We were each served a tray full of little labeled cups, full of mysterious liquids that definitely were not beer.

Jon Roll, a UW prof who teaches beer brewing courses, led the discussion. He explained that the tongue really only tastes 5 things, sweet, salty, sour, bitter, and umami. The rest of our sense of “taste” is actually the aromas of food, experienced by the nose.  The nose senses food aromas through two pathways. First, we inhale the scent of the food outside our mouths. We typically call this smell. However, when the aromas of food in our mouths reaches the nose through the nasal passageway, we refer to that as the taste of the food. Even though the olfactory nerves in the nose are responding the same we seem to mentally seperate these two processes.  We say that the roasting turkey smells good and then it tastes good too.  But when we say we are enjoying the taste, it is largely because of the smell.

We tasted sweet water. Then we tasted really sweet water. Blech. Then, going back for another sip of the first sample was striking, it tastes just like water.  Roll explained that the taste buds can get desensitized pretty easily to some flavors, so we stop registering them.  This is potentially a big concern for the manufactures of food, how to keep something tasting good all the way to the last sip without losing our sensitivity to the flavor?

Most of the receptors in the mouth for bitterness, we discovered, are near the back of the tongue and throat. Because of this, professional beer tasters always swallow the beer they are testing.  Unlike wine tasters, who can swirl it around in their mouths and then spit it out to describe the flavors, the bitterness component of beer is best sensed by swallowing. No one in the audience seemed upset to find out that we had to actually drink the beer.

To understand the role of our noses, Roll asked us to pinch our noses tight while rubbing a gum drop on our tongue.  It just tasted sweet. It wasn’t until you released your nose that the flavor of cinnamon became apparent. We looked silly, but we did it again. Same thing with spearmint. And orange.

However, your tongue does more that just taste the 5 famous flavors.  It also has physical responses to some flavors that can be called mouth-feel.  Taste something strongly sour, and your mouth puckers up and starts salivation.  Drink tea or red wine and the tannins can make your tongue feel strangely dry, even though you are drinking a liquid.

When we were finally served a sampler of beers, everyone was better equipped to describe what they tasted.  People sipped beer holding their noses, and then re-sipped with noses functional normally.  Complex beers like the porter we tried have a progression of flavors, from the early aromas of coffee or caramel, sweet in the middle, a pleasantly bitter finish.  In my opinion, it was the best one at the event. But, other people preferred the floral and bitter IPA.  To each their own tastes, apparently.