Salivary amylase will be active for only an hour or so because the optimum pH for activity of amylase is about 6.7–7.0 which is available in the mouth but the pH of the stomach is acidic around 1-2 due to which the amylase enzyme becomes inactive in short-time.
The lingual lipase enzyme is present in the saliva but isn't active until reaching the stomach because this enzyme is acid stable and works efficiently in the stomach, not in the mouth.
Amylase enzyme is secreted in the mouth and is responsible for the breakdown of starch in food into sugars and it starts acting as soon as we put food in the mouth whereas Lingual lipase enzyme is secreted along with saliva but it is not active in the mouth rather its activity starts in the stomach which is responsible for the degradation of triacylglycerol molecules.
