338 Missouri Agricultural Report. 



For this reason they should be given no starchy foods before that time. 

 It is customary to emphasize the thorough chewing of meats where the 

 effect is only mechanical ; but it should be insisted upon also that chil- 

 dren learn to chew starchy food well because of both the mechanical 

 and chemical effect of the saliva on them. 



"Leaving the mouth the food passes through the aesophogus into 

 the stomach. In the stomach the food has poured upon it another 

 secretion known as the gastric juice. This juice is made acid by a 

 small amount muriatic acid formed in the stomach. In the gastric 

 secretion are two enzymes, rennin and pepsin. Rennin acts only on 

 the proteid portions of milk (the curd). It coagulates this into a 

 very soft mass. Its action is noticeable in babies who ''throw up" their 

 milk. Commercial rennin, which is used in making cheese, is extracted 

 from the stomach of mammals. Pepsin acts upon the proteids of all 

 foods, changing it into peptones, substances which may be absorbed by 

 the body. The mechanical action is produced b}^ the churning process 

 in the stomach, and is an aid both to digestion and absorption. 



''From the stomach the food passes into the small intestine where 

 all food capable of digestion, which has not been acted upon in the 

 mouth or stomach, is digested. The pancreatic secretion which is poured 

 into the small intestines is an alkaline solution containing three en- 

 zymes, trypsin, amylopsin and lipase. Trypsin changes the remaining 

 proteids of the food into peptones ; amylopsin, the remaining starch into 

 glucose, and lipase, together with the bile, which also enters the small 

 intestines, seems to digest the fat. This action is not w^ell luiderstood 

 but experiments on dogs show that if the bile be removed from the 

 animal practically all the fats pass through the body and are thrown 

 off as waste. 



"Summed up, we have starches and sugars, by digestion in the 

 mouth and small intestine, changed into glucose which is capable of 

 absorption ; proteids digested in the stomach and small intestines by be- 

 ing changed into peptones which are readily absorbed, and fats which 

 are digested in the small intestines. 



"Raw starch is digested only very slowly by the human body, al- 

 though cattle and horses digest it easily. Raw proteid, if it be from 

 the animal, is more easily digested cooked; but is usually cooked to im- 

 prove the flavor. For cooking proteids, especially meat, after searing 

 the outside to prevent the juice from escaping the meat should be 

 cooked at a low temperature, from 75 degrees to 85 degrees Centi- 

 grade, for a long time so that the proteid will be coagulated but not 

 hardened, and connective tissues be softened. In cereals prolonged 

 cooking at a high temperature is desirable. 



