How much dietary starch is likely to be converted to maltose in the stomach relative to the mouth and esophagus?

Question

I'm trying to answer the questions at the end of my lab.  Please help!

Answer 1

To follow up on Jamie's answer: as he says, starch can be broken down by salivary amylase in the mouth and esophagus.  Salivary amylase is not active in the stomach because it has a pH optimum near 7, while the stomach pH is close to 2 (much more acidic).  The stomach secretes pepsin (technically, pepsinogen that is converted into pepsin; pepsin breaks down proteins) and gastric lipase (which breaks down fats), but no enzymes that break down carbohydrates like starch.

 

So considerable digestion of dietary starch will be converted into maltose in the mouth and esophagus.

 

Essentially none will be converted in the stomach.

 

Any remaining starch will be broken down by pancreatic amylase in the small intestine.

Answer 2

The conversion of starches to maltose or sugar is enabled by the enzyme amylase which is produced in the salivary glands.  Amylase is introduced to and mixed with your food by your saliva and mastication or chewing.