TRANSPORT AND STORAGE OF FOOD 425 
temperature. It has been found that if the advantages of quick freezing 
are to be retained, the meat must be stored at a temperature not higher 
than — 20°C. 
Chilling —The fact that freezing is an unsatisfactory process for beef has 
led to alternative methods of storage being explored. As is well known, 
much of our beef comes from foreign countries, and it may be asked how it is 
that it is brought here so successfully. As the ideal method appears to be 
storage at a temperature not higher than about — 10° C., the question arises, 
“Is imported beef stored at this low temperature ?’ The answer is that the 
bulk of such meat is not frozen : it is only chilled—i.e. the meat is cooled 
only to temperatures at which little or no ice is formed in it. The tempera- 
ture employed is about —1°C. At this level, as already stated, the growth 
of micro-organisms, while retarded, is not arrested, and I have already 
pointed out that, were the bacterial contamination initially high, the meat 
would become unfit for food after a week or so. At this point I would 
like to pay tribute to the importers of chilled beef to Great Britain, for the 
normal life of such beef is five weeks or more, a success which is largely 
due to the admirable control that has been established over the conditions 
from the slaughter-house in South America through the whole chain of 
transport to the retail butcher here. In other words, the detrimental 
effect of micro-organisms has been fully realised, and the greatest care is 
taken to keep such contamination at the minimum. 
It is clear that, even if the greatest precautions were taken, since the 
normal life of chilled beef at — 1° C. is only about five weeks, export of chilled 
beef from Australia and New Zealand is not, or rather was not, a feasible 
proposition. ‘This fact, and the desirability of increasing the life of chilled 
_ beef, led to researches being made with a view to finding other means than 
low temperature of controlling the growth of micro-organisms. ‘To some 
_ extent the growth can be controlled by regulating the humidity of the ship’s 
_ hold, for the lower the humidity the slower the rate of growth. If, however, 
the humidity is very low, the loss of weight by evaporation from the meat is 
considerable, and there is thus a strict economic limit to the extent to which 
the humidity can be lowered. How much this question of loss of weight 
means will be gathered from the statement that if the present loss of weight 
in New Zealand mutton and lamb could be reduced by one-quarter, it 
would be worth £100,000 a year to the industry. It was desirable therefore 
to look in other directions than controlled humidity, and within the last 
few years research has discovered still another means of controlling bacterial 
growth. 
__ Gas-storage.—It so happens that the most important micro-organisms 
attacking meat, both bacteria and moulds, are specially susceptible to carbon 
dioxide, and that, at temperatures in the region of the freezing-point, a con- 
_ centration of 10 to 20 per cent. of this gas so delays their growth as to double 
e life of the beef. While the mode of action of carbon dioxide is not yet 
lear, it may be due to the consequent change produced in the hydrogen-ion 
ncentration—i.e. in the acidity of the meat. On the other hand, there is 
some evidence that the carbon dioxide acts directly on the micro-organisms 
by depressing their respiratory activity. Further research will clear up 
these points. It will no doubt be asked why the concentration of carbon 
dioxide should not be still further increased, so as to retard even more, 
‘or possibly to inhibit, the growth of micro-organisms. Unfortunately, 
however, at higher concentrations the carbon dioxide has adverse effects in 
other directions, which I will now describe. 
__Bloom.—Most people know what is meant when meat is said to have a good 
“bloom ’: it constitutes that bright, attractive appearance of freshly killed 
Q 
