92 PRELIMINARY COLD STORAGE STUDIES. 



vided with their natural environment, they will multiply when the 

 medium is in a frozen condition. The experimental work which has 

 been done in the past' has used chiefly the usual laboratory media and 

 pure cultures of laboratory-grown bacteria. It is perfectly possible 

 that such conditions, since they are not comparable with those natu- 

 rally prevailing, will lead to some erroneous results, and in view of 

 recently demonstrated facts it becomes necessary to attack the prob- 

 lem of bacterial development in flesh foods from this point of view 

 before the assumption can be accepted that temperatures below freez- 

 ing guarantee a freedom from bacterial activity. 



Observations on the growth of bacteria under the conditions of the 

 very low temperature cold-storage houses, such as almost universally 

 prevail in the United States, are entirely lacking. What informa- 

 tion is to be had on the growth of bacteria in flesh when cold-stored 

 comes from abroad, chiefly from Germany, where the temperature 

 of the "Kuhlhaus" rarely reaches C. and is commonly several 

 degrees above it. Exposed to such temperatures there is a unanimity 

 of opinion regarding the "ripening" of the flesh, and the tenderness 

 and flavor acquired in the course of it. To what this maturation is 

 due, however, is not so well settled. Glage a would ascribe much of 

 the flavor to "aroma-producing" bacteria which develop best at low 

 temperatures; Miiller, 6 on the other hand, believes that the process 

 is essentially dependent upon the enzymes of the flesh itself. He 

 holds that the temperature of the chilling room prevents putrefac- 

 tion, and, therefore, all those poisonous properties dependent upon 

 putrefaction, while it assists natural autolysis. Neither does he con- 

 sider c that the changes in the ripening of meat are the early stages of 

 putrefaction. 



The observations made under commercial conditions he has rein- 

 forced by a study of freshly killed, bichlorid-washed fish, which 

 was kept at C. After 5 days there was an unpleasant taste 

 and a characteristic odor, both of which appeared in 2 days when 

 kept at 12 C. Schmidt-Nielsens kept a carp packed in ice for 

 14 days, and, though bacteria-free, it had, at the expiration of 

 the above period, so unpleasant a taste that it was unfit for food. 

 Miiller determined the amount of nitrogen soluble in water in both 

 mammalian and fish muscle kept at C., concluding therefrom that 

 an autolysis proceeds. He found that muscle loses its elasticity, 

 becomes tender, and the clear red color changes to an opaque, dark 

 red. The odor after 3 days at 25 C. or at C. after 14 days is 

 strongly acid. 



Zts. Fleisch- Milchhygiene, 1900-1901, p. 131. 



& Der Reifimgsprozess des Fleisches, Zts. Fleisch- Milchhygiene, 1904, 14: 217 

 and 337. 



cArchiv Hyg., 1903, 47: 127. 



