THE PRESERVATION OF FOOD BY COLD 547 



partially destroyed by boiling for 15 minutes. It may be suggested 

 that organisms of this type existing in frozen poultry might well account 

 for poisonous effects produced by the flesh after roasting or boiling. 



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 

 microorganisms prevented. Unquestionably there is a marked differ- 

 ence between the ordinary cold-storage egg and the strictly fresh egg, 

 but to what extent this deterioration may be due to errors in storage, 

 such as inaccurate control of temperature and humidity, use of odorif- 

 erous crates for packing, decomposition changes previous to storage, 

 too rapid chilling of the eggs, or too rapid warming of them after 

 removal from storage, and to what extent it is inherent in the most 

 perfect cold-storage procedure, is still somewhat uncertain. Doubt- 

 less a certain amount of deterioration, especially the loss of the peculiar 

 flavor of the fresh egg, is unavoidable in any method of prolonged 

 storage. The discrimination in price in favor of new-laid eggs in the 

 market is an indication of difference in actual value, and the sale of 

 cold-storage eggs for new-laid or strictly fresh eggs is generally recog- 

 nized as a fraud by the purchaser. The cold-storage egg is nevertheless 

 a very valuable food and the economic importance of saving the over- 

 abundant supply produced during the spring for use during the colder 

 season of the year makes this industry a great benefaction to the public. 

 Suitable regulation may be expected to remove its objectionable 

 features. 



MILK AND BUTTER. Milk as ordinarily sold at retail is not subject 

 to sufficient seasonal change in market price to make its prolonged 

 storage advisable. But milk is so rapidly changed by bacterial activity 

 at ordinary temperatures that efficient dairy methods necessarily in- 



