Starch is changed into disaccharides in the presence of:

Explanation

Dietary carbohydrates principally consist of polysaccharides : Starch and glycogen. It contains disaccharides and small amounts of monosaccharides.
Digestion in mouth : Digestion of carbohydrates starts at the mouth, where they come in contact with saliva during mastication. Saliva contains carbohydrate splitting enzyme called Salivay amylase (ptyalin). This enzyme hydrolyses the starch into disaccharides (maltose).
Starch`overset("amylase")` Disaccharides (maltose).
Digestion in stomach : Ptyalin action stops in stomach when pH falls to 3.0. No carbohydrate splitting enzymes are available in gastric juice. Some dietary sucrose may be hydrolysed by HCI.
Digestion in small intestine : Chyme reaches the duodenum from stomach where it meets pancreatic juice. Carbohydrates in the chyme are hydrolysed by the pancreatic amylase into disaccharides. Intestinal disaccharidases act on the disaccharides and convert them into monosaccharides.Carbohydrates `overset(prop "Amylase") to ` Maltose, Sucrose, Lactose
Maltose `overset("Maltase")to` Glucose + Glucose Sucrose `overset("Invertase")` Glucose + Fructose
Lactose `overset("Lactase") to ` Glucose + Galactose