2 BULLETIN 51, U. S. DEPARTMENT OF AGRICULTUEE. 



the exact knowledge of the composition or history of the egg itself. 

 The fanner's wife, accustomed to the fresh eggs of the farm, dis- 

 cards as imfit for food an egg which the city baker would, with a 

 clear conscience, serve to his own family. The difference in the point 

 of view has progressed even to the savants who have held opposite 

 and positive opinions concerning the wholesomeness or desirability 

 of certain eggs, especially of those known in commerce as '' frozen " 

 or " desiccated." 



Investigation has shown that when the egg is laid it is of a fairly 

 constant chemical composition and contains but few bacteria or 

 molds. In the vicissitudes of marketing, with its attendant unde- 

 sirable conditions, eggs in the shell undergo a variety of changes, 

 referable, almost exclusively, to the mode of handling. These 

 changes, their effect upon the food and market value of the egg, 

 and the means by which they can be reduced to a minimum have 

 been, and still are, a subject of investigation by the Department of 

 Agriculture cooperatively^ with every branch of the egg-marketing 

 industry. 



The great variety of conditions to which an egg is subjected and 

 its sensibility to temperature, humidity, odors, etc., result in many 

 evidences of deterioration in the eggs on the market. The extent to 

 which such downward 'changes are reflected in the composition of the 

 egg, together with their recognition by physical, chemical, and bacte- 

 riologic methods, is the subject of the present report. 



The work has been done as part of an investigation of the prepara- 

 tion of frozen and dried eggs. It is the foundation on which to build 

 all the other phases of the . investigation, such as the construction 

 of the apartments in which egg breaking for food purposes can pro- 

 ceed ; the methods used to guard against bacterial contamination ; the 

 systematic application by the employees in the packing houses of the 

 knowledge gained by scientific research to increase accuracy and 

 efficiency ; the quality of the output of the houses under old and new 

 conditions, and the behavior of those products when they reach the 

 hands of the baker, who, for this investigation, may represent the 

 consumer. These diverse parts of the work will be reported in a 

 series of publications of which this is the first. It will be observed, 

 therefore, that the subject is discussed from the industrial viewpoint, 

 even though it is essentially a laboratory study. 



The individual eggs, and some of the composite egg samples, were 

 opened in the laboratory ; the samples designated " commercial " 

 were opened by a bacteriologist in packing houses where the sur- 

 roundings were as clean as, or cleaner than, in the laboratory and 

 where all utenstils were sterilized. 



The information given in this report has been gathered in south- 

 western Iowa, northern Tennessee, and the valley of the Missouri 

 from the northern liorder of loAva to the central part of Kansas. 



