380 MICROBIOLOGY OF SPECIAL INDUSTRIES. 



Gelatin is prepared by boiling bones and tendons, sometimes also horn and hide 

 scraps and concentrating the gelatin which dissolves from these. 



Somatose, sar co-peptone and related so-called predigested protein foods are mixtures 

 of albumoses and peptones prepared by the artificial digestion and drying of proteins, 

 usually flesh. The product is marketed as a powder. 



Milk, either with or without its butter fat, is dried by being sprayed into a warm 

 compartment from which the air is partly exhausted. It dries immediately, in the form 

 of a very fine powder. This powder, if thoroughly dry, will keep well and is finding an 

 extensive use. The high sugar content of this powder is instrumental in preventing the 

 development of microorganisms (p. 366). 



Eggs are dried in much the same manner as milk and the product is being used 

 extensively at the present time by bakers. 



Meats are frequently preserved by a combination of drying and the 

 action of certain antiseptics. The salting of meat owes its effectiveness 

 in part to the abstraction of water. In most cases, the surface of the 

 meat and probably even 'the other portions are protected in large measure 

 by the diffusion of the fat and the saturation of tissues and by the forma- 

 tion of water-proof fat films. The autolytic enzymes are active in the 

 fresh meat and soon become inert upon the removal of water. The 

 organisms responsible for decay of preserved meats and flesh foods are 

 usually bacteria. Some of these break down the protein into simpler 

 chemical compounds, of which a few are poisonous. 



