Which substance is the main contributor to carbohydrate digestion in the mouth?

Salivary amylase is the enzyme primarily responsible for initiating the digestion of carbohydrates in the mouth. This enzyme is secreted by the salivary glands and begins the process of breaking down starches into simpler sugars, such as maltose. The presence of salivary amylase in saliva facilitates the breakdown of complex carbohydrates immediately as food is chewed and mixed with saliva, preparing it for further digestion in the stomach and small intestine.

Pepsin, another enzyme mentioned, is primarily active in the stomach where it breaks down proteins into peptides but does not play a role in carbohydrate digestion in the mouth. Bile is produced by the liver and stored in the gallbladder; it aids in the digestion and absorption of fats in the small intestine rather than carbohydrates. Gastric lipase, similar to bile, is involved in fat digestion, specifically within the stomach, and does not contribute to carbohydrate digestion. Thus, salivary amylase is definitively the key enzyme responsible for carbohydrate digestion in the mouth.