THE PRESERVATION OF FOOD BY COLD 475 



rapidly chilled by immersion in ice watey or packing in ice immediately 

 after death, and are frozen as quickly as possible. During storage in 

 the frozen condition microbic activity is suspended, but in the sub- 

 sequent thawing the same physical and biological changes occur as in 

 frozen meat. When fish and poultry are stored in the undrawn condi- 

 tion there is an abundant supply of bacteria at hand in the intestinal 

 contents ready to multiply energetically during the chilling and thawing 

 stages. It would appear desirable that the poultry should be killed 

 and dressed with great care previous to freezing and that the period 

 of chilling should be shortened as much as possible. Practically, how- 

 ever, it has been found that the dressing, of poultry, as ordinarily done, 

 previous to storage leads to such an extensive soiling of the edible flesh 

 of the birds that their condition at the end of the storage period is often 

 less satisfactory than that of undrawn frozen poultry, not only in gross 

 appearance but also in respect to microbic content and chemical com- 

 position. Most frozen poultry is, therefore, stored in the undrawn 

 condition. 



The tendency of such food to undergo decomposition after thawing 

 should be clearly recognized. Its sale as fresh or as chilled food is a 

 fraud upon the purchaser. In fact many individuals seem to be pecu- 

 liarly liable to suffer digestive disturbances after eating frozen poultry 

 and such persons should avoid its use. 



The nature and source of the bacteria which produce poisonous 

 changes in poultry are not definitely known, but there is some evidence 

 indicating that they belong to the para-colon group and that they are 

 derived from the intestinal contents of the fowls. 



Eggs. — ^The cold storage of eggs is an industry which has attained 

 large proportions in recent years. A very constant storage temperature 

 between -[-0.5° and +1° is essential for the best results. The hu- 

 midity of the atmosphere is also of very great importance, as a dry air 

 causes extensive evaporation from the egg and a too moist air favors the 

 development of microorganisms on the exterior of the shell and the 

 absorption of their products and even their penetration into the egg. 

 A constant humidity of 70 per cent saturation has been found to be the 

 best. Storage at this temperature and humidity greatly retards the 

 growth of microorganisms and definitely inhibits the ordinary putre- 

 faction*||of eggs. The activity of the intrinsic enzymes of the egg are 

 not necessarily inhibited by this temperature, nor is the growth of all 



