1921.] Wright.—Chemical Technology of Meat Industry. 77 
soon enough or that through some defect the temperature in the cold 
store had been inadequate to prevent bacterial growth. 
Freezing of Beef. (ii.) 
It has been found that, while mutton can be frozen and subsequently 
thawed out without any apparent alteration to the tissue, beef very often 
cannot, and it appears likely that the physical and chemical properties of the 
muscle-fibre in beef are altered during the process of freezing so that there 
is a separation of the liquid and solid constituents, and the beef on thawing 
drips freely. 
Recent w T ork seems to indicate that the solution of the difficulty lies in 
freezing the beef sufficiently rapidly, and experimentally it has been found 
that when the beef is rapidly frozen by immersing in brine cooled to 
— 20° C. the propensity to drip on thawing is eliminated. Attempts, 
however, upon a commercial scale have not so far been successful, for the 
reason that it has not yet been possible to remove the heat sufficiently 
rapidly from quarters of beef. 
Moulds. (10, 11, 17.) 
The subject of moulds which have been found to develop upon refrigerated 
produce has been one of controversy, for, although there has been a belief 
that certain moulds can develop under cold-storage conditions, there has 
been doubt as to whether the growth of the moulds found upon cold- 
storage meats has not been due either to a breakdown of the plant or to 
defective insulation. 
It has now been shown that the mould producing 44 black-spot,” a 
Cladesporium, will grow and produce spores at least 5° C. below freezing- 
point (23° F.). This mould develops more rapidly if, before being placed 
in the cold, the meat with the spores is kept for about twenty-four hours 
at ordinary temperature, thus allowing the early stages of germination 
to take place under normal conditions. Growth is found to be very slow 
at low temperatures, but it is greatly enhanced if the temperature is raised 
to 0° C. (32° F.). So far the 44 black-spot ” mould is the only one found 
to grow at a temperature considerably below r 0° C., but several others 
develop fairly well at freezing-point. 
The 44 black-spot ” fungus appears to be identical with the mould 
described by Dr. Klein many years ago and named Cladesporium herbarium. 
Despite the fact that Cladesporium herbarium can grow at 23° F., the 
position should not prejudice the refrigerated produce, because it can only 
be possible for the mould in question to grow when the temperature is 
substantially above that usually maintained under cold-storage conditions, 
and it will scarcely be held that 23° F. is a usual or safe temperature at 
which to hold cold-storage products such as mutton or beef. 
44 Black-spot ” mould due to Cladesporium herbarium is frequently 
found in chilled beef. It is, however, a surface infection, and experiments 
carried out have shown that it is harmless to animals. 
44 Red-spot ” upon meats has been found to be due to Bacillus prodigiosus; 
44 brown-spot ” upon chilled beef has been found to be due to a yeast; 
while another 44 black-spot ” mould has been identified as Oidivm carnis. 
It is scarcely practicable commercially to altogether exclude from con¬ 
tact with the surface of meat the mould spores or bacteria which are 
almost universally present in the ordinary atmosphere. There are, however, 
certain precautions which have been found useful and which may be 
applied without incurring heavy expense. 
