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What is the reason that when chewing a piece of bread, it intially tastes sweet and after a few minutes, it tastes bitter.
Salivary amylase is an enzyme which breaks down the starches found in
bread to sugar. This happens very rapidly, so some sugars are in your
mouth before being swallowed, making the bread taste sweet. Sugars
dissolve in your saliva and get swallowed over the course of a few
minutes -- eventually all the carbohydrates are converted or swallowed,
leaving the other components of the bread -- which may have a very
different taste, depending on what kind of bread it is.
(Some breads have added sugar or high-fructose corn syrup added as sweeteners).
(republished on 07/13/06)
Follow-Up #1: enzymes and runny soup
Your answer about salivary amylase makes me wonder...
I used to be a food server and would serve thick soups, such as cream of potato or clam chowder, to customers. When clearning their bowls away, they would often leave some of the soup remaining. But, the remaining soup would be runny. Is this because of amylase transferring from their spoon to the soup?
- Paddy (age 47)
North Bend, WA, USA
Your theory sounds very reasonable to me. However, my Bostonian wife was so shocked at the thought of any clam chowder being left in the bowl that she came up with an alternate theory. Maybe, she said, it's a selection bias effect. Only people who order diet chowder would leave any in the bowl, and it tends to be runny to begin with. The choice between these theories (and others) could be resolved with more data.
(published on 01/16/12)
Follow-up on this answer.