FATS 67 



during which the starch molecule is split into maltose and 

 erythrodextrin. The latter again into maltose and achroodextrin; 

 achroodextrin again into maltose and a still simpler dextrin, 

 and so on until only maltose results. In the intestinal secretion 

 there is an enzyme which aids amylopsin in the conversion 

 of starch to maltose. The sugars thus formed and others, 

 eaten as such, are by means of inverting enzymes (invertase 

 and maltase) of the intestine changed to monosaccharides. 

 This is illustrated by the following equations : 



C 12 H 22 O n + H 2 O = C 6 H 12 O 6 + CeH.A 



Maltose. Dextrose. Dextrose. 



Ci 2 H 22 On + H 2 = CgH^Og + C 6 H ]2 O 6 



Cane sugar. Dextrose. Levulose. 



It has been found that cane sugar may also be converted 

 to dextrose and levulose in the stomach. Carbohydrates that 

 escape digestion and absorption and reach the large intestine 

 are largely destroyed by bacteria. 



Fats. These are but slightly changed before they reach 

 the fat-splitting ferment, steapsin, of the pancreatic juice, 

 except that they are separated from the connective tissue 

 by the action of the teeth and proteolytic enzymes, and are 

 partially melted by the heat of the body in the stomach. In 

 the intestine fats are changed to glycerin and a corresponding 

 fatty acid. The latter may unite with bases present to form 

 soaps, which emulsify the remaining unaltered fat. .According 

 to one view, fat is mainly absorbed in the form of an emulsion. 

 According to another and later view, all of it is converted to 

 fatty acid and glycerin, absorbed as such, and then recombined 

 to form neutral fat. While considering the action of digestive 

 juices, it is interesting and important to remember that the 

 ferment rennin of the gastric juice coagulates milk. The casein 

 of the milk under the influence of the enzyme undergoes a 

 hydrolytic cleavage, with the formation of paracasein and 

 whey protein. Paracasein unites with calcium to form the 

 insoluble curd. The action of rennin is confined to milk, and 

 the value of the curdling action lies probably in an easier con- 

 version of the milk proteins in the coagulated form. The 

 digestion of milk after coagulation is carried on by the enzymes 

 of the gastric and pancreatic juices. 



