8 CLEAN MILK 



over 0.2%, is unfit for pasteurization. A high acidity generally 

 means an excess of spore-bearing germs which are not killed 

 by pasteurization. These induce putrefactive changes in milk with 

 the production of poisons or ptomaines from decomposition of the 

 milk — not directly from the growth of germs. Milk and cream 

 should, then, be pasteurized when fresh, since when old the spore- 

 bearing germs are apt to be abundant. Commercial pasteurization 

 is therefore more fitly done in the country at the creamery. 



There are certain substances naturally present in cows' milk 

 exactly resembling those which bring about the digestion of food in 

 the stomach and bowels of man and animals. These chemical sub- 

 stances in milk or in the digestive organs are called ferments (or 

 enzymes). They appear to aid the digestibility of milk, particularly 

 in infants, and are destroyed by heating milk over 150 F., or at a 

 lower temperature if the milk is repeatedly heated. These natural 

 ferments in milk one must keep distinct in the mind from those 

 ferments formed by germs accidentally contaminating milk (see 

 below). It is generally accepted, however, that babies will not 

 thrive so well on pasteurized milk for long periods, as on clean, un- 

 heated milk, and occasionally develop malnutrition, anemia, rickets 

 and scurvy. The last may be prevented by feeding infants one 

 tablespoonful of orange juice twice daily. It is known that scurvy 

 in infants sometimes occurs in infants fed on breast milk and on 

 raw cows' milk. I have had a case in my own practice in a bre.ast- 

 fed baby. The milk was very low in fat (1.55% ) an d probably also 

 in proteids. 



Moreover, it has been contended that pasteurized milk is more 

 digestible than unheated milk, since heating milk prevents the fat 

 globules from running together, and since heating lessens the curd- 

 ling of milk in the stomach by rennin. The same effect is seen out- 

 side the body in the action of rennet on raw and heated milk. Fin- 

 ally, there, are experiments that seem to show that pasteurized milk 

 is absorbed more readily than raw milk from the bowels. 



