Ptyalin hydrolysis does not continue in the stomach because it is destroyed by the stomach once it enter the stomach.
Ptyalin is an amylase enzyme commonly found in the saliva of humans and animals. This enzyme is secreted in the mouth ( buccal cavity) and catalyze the hydrolysis of starch into maltose and dextrin. Immediately the starch leaves the mouth and enter the stomach, stomach acids destroy the ptyalin.