212 The N.Z. Journal of Science and Technology. [Nov. 
that a sufficiently low temperature absolutely prevents growth and multi¬ 
plication of bacteria, and stops all bacterial action. 
Many observations have been recorded and many experiments have 
been carried out in order to discover whether bacteria are able to penetrate 
into frozen meats at the temperature of cold storage, and in every case it 
has been found that, while upon the surface of the frozen meat might be 
found bacteria, just as in the case of fresh meat, the interior was sterile and 
free from bacteria. The experiments might be quoted at length, but one 
only, and that a most important one, will be noted. A tub of water was 
brought nearly to freezing-point in a freezing-chamber, and to it was added 
a quantity of a suspension in water of many thousand millions of the micro¬ 
organisms of putrefaction, cultured and grown from putrefying meat. 
Several pieces of meat were now placed in the tub and the whole allowed to 
freeze. Thus the surfaces of the meat were in intimate contact with a 
frozen mass containing immense numbers of putrefactive bacteria. The 
conditions were ideal for bacterial invasion of the meat, if such were possible 
at the temperatures varying from 15° to 20° C. below the freezing-point 
of water. At the end of five months sections of the meat showed no indica¬ 
tion of the power of bacteria to penetrate into frozen meat. 
It is a matter of knowledge that cold-storage meats are more tender 
than fresh meats, and it has been found that the changes associated with 
this increased tenderness are due to the gradual and limited work of natural 
enzymes, such as pepsin and trypsin present in normal flesh, which cause 
a certain amount of predigestion similiar to that occurring when fresh meats 
are kept for a day or two after slaughter. It has now been shown that 
several enzymes are present in frozen meats, and they have been isolated 
and identified in such meats up to six months of cold storage, and it is 
apparent that the changes found in cold-storage meats are due in a large 
measure to these substances, and, while enzyme action goes on but slowly 
at low temperatures, the action is not stopped. This is the reason why 
refrigerated produce, when thawed, is usually ready for immediate con¬ 
sumption, and does not require keeping. 
It has been found that under certain conditions some species of micro¬ 
organisms, especially moulds, may develop upon refrigerated produce, and, 
although they do not otherwise change it, may 'cause discoloration. In 
some cases these moulds have been isolated and grown artificially. As, 
however, this subject is one at present under investigation by the author 
it is not desirable at present to discuss the cause and remedy, but it may be 
stated that the moulds in question are harmless to animals either when they 
are fed upon them or when the moulds and their products are injected 
subcutaneously and intraperitoneally. There is also evidence that a 
harmless aerobic coccus is symbiotic with the mould. 
Oleomargarine. 
In the frozen-meat industry oleomargarine is the caul and kidney fat 
of sheep and cattle, which is washed and chilled, the hardened fat being 
then cut up and the disintegrated mass rendered in jacketed pans or 
melting - kettles at a temperature as low as is consistent with the 
thorough melting of the fat, so that the membranous tissue is separated 
and sinks to the bottom of the rendering-kettle, while the melted fat 
rises to the top of the vessel. After clarifying, further refining, and 
settling the fat is cooled to the proper temperature for “ seeding ” or 
crystallizing out. 
