Normal phlegm, when first produced, is relatively thin and clear, and mildly sweet in taste. The taste of normal saliva is mildly sweet or bland, but if one's saliva tastes unduly sweet, sour, acrid or bitter, it may indicate morbid qualitative changes in the Phlegmatic humor.
So, what could cause a sweet taste in your mouth?
A sweet taste in the mouth may be caused by diabetes. Diabetes is a common cause of a sweet taste in the mouth. Uncontrolled diabetes can result in high levels of sugar in the blood. Diabetes can sometimes cause a sweet taste in the mouth and is often accompanied by other symptoms.
Why does water taste sweet to me?
Additional causes of water tasting sweet may be attributed to something you've recently eaten. Typically, when you eat something sour, your saliva produces chemicals that trigger a sweet-tasting sensation. However, sometimes the sweet taste of water is not actually something you taste at all—it's something you smell.
Why does a piece of bread taste sweet when chewed for some time?
It is this chain of sugar molecules that we call starch. This is why the bread starts to taste sweet after lots of chewing - the amylase enzyme is breaking down the starch and turning it into glucose. Amylase isn't the only enzyme to break down food into molecules we can absorb.