92 PRELIMINARY COLD STORAGE STUDIES. 



vicled 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 imder the conditions of the 

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

 prevail in the United States, are entirely lacking. TThat 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 '•Kiihlhaus" rarely reaches C 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: Muller, 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. Xeither 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 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 C. Schmidt-Xielsens 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 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 0° C. after 14 days is 

 strongly acid. 



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



b Der Eeifangsprozess des Fleisches. Zrs. Fleisch- Milckhygiene,. 1904. 14- 217 

 and 337. 



cArchiv Hvg.. 1903. 47: 127. 



