Answer to Question 1
In order for a substance to be tasted, it must dissolve in liquid or saliva, which is 99.5 percent water. When food comes into the mouth, bits of it are dissolved in the saliva pools of the taste buds. Here, the food contacts the cilia of the gustatory cells which send messages to the brain. The brain translates these messages into tastes. The more moisture a food contains, the more molecules can be spread to trigger flavor.
Answer to Question 2
Bitter tastes are caused by compounds such as caffeine, theobromine, phenolic compounds, and alkaloids. Acidic compounds made up of hydrogen (H+) ion concentrations cause a food to taste sour. Acids are present in fruits, vinegar, and certain vegetables. Salty tastes are evident when food contains ionized salts such as the salt ions Na+ in sodium chloride (NaCl) or other salts. Sugar's sweetness comes from the chemical configuration of food molecules. Sugars, glycols, alcohols, and aldehydes cause sweet tastes.
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Activation of the Primary Gustatory Cortex by Taste Stimuli
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