78 
The N.Z. Journal of Science and Technology. [April 
Dryness in the surroundings is to be sought, for damp encourages the 
growths ; whilst moist coverings on the meat itself should especially be 
avoided. 
At intervals, when the chambers are cleansed, the surfaces should be 
sterilized by vapour or spray of formaldehyde or sulphurous acid, and 
then dried by a current of air. 
The cloth coverings, either calico bags or 44 stockingette,” should be 
effectually sterilized by heat. 
The maintenance of a temperature substantially below that at which 
the organism can grow is, of course, essential. 
Meat-canning. (7, 17.) 
The term 44 canned ” as applied to food products put up in hermetically 
sealed packages is capable of more than one meaning, but the generally 
accepted application means any food put up in any container which 
has been hermetically sealed and the preservation accomplished through 
sterilization by heat. 
In order to secure successful canning of meats it is essential to destro}" 
all the bacteria present in the material, and to seal the can so that no fresh 
invasion by bacteria or other micro-organisms can occur. This is accom¬ 
plished by heating the contents to a temperature that kills not only the 
bacteria themselves, but also the most resistant spores. 
Meat products, as a rule, contain highly resistant organisms ; besides 
which, the majority of these foods are of such a consistency that heat 
penetrates them very slowly. As a class they usually require the heaviest 
processing. 
The methods of canning vary to some extent with the kind of meat 
that is to be preserved and the ideas of the individual manufacturer. 
Differences occur in time, temperature, methods of handling, and apparatus, 
slight in themselves, but of such a nature as to make it impracticable to 
give more than a general description which embodies the essential features 
of the methods commonly employed. 
The meat selected for preserving is boned and cut into pieces of from 
1 lb. to 2 lb. or 3 lb., and trimmed to remove as much gristle as possible 
and the larger pieces of fat. The size of the pieces of meat will be 
determined largely by the weight which is to be filled into the individual 
cans. It is desirable that the pieces of meat be as uniform in size as 
practicable, in order that the larger pieces may be thoroughly cooked before 
the smaller ones begin to disintegrate. 
If the meat is intended for roast or boiled it is now parboiled, or, as 
technically called, subjected to 4 ' shrinking,” because to produce a market¬ 
able article it is necessary that the meat be cooked before it is canned. 
Parboiling also serves another purpose: by removing a large quantity 
of water it increases the relative percentage of nutritious compounds, and 
thus forms a somewhat concentrated food. Thus 30 oz. of canned roast 
beef contains the equivalent of nearly 49 oz. of fresh beef. 
The parboiled meat is packed in cans, either by machine or by hand. 
To each can is added a proportion of liquor from the parboiling or from 
meat-extract. In some cases salt is dissolved in this liquor for the purpose 
of seasoning. The caps are now soldered on the cans. 
The cans are now processed. This operation is probably the most 
important of all in canning, for if this fails all others come to naught. It 
is an easy matter to sterilize any product by giving a sufficiently high 
temperature for a short time, by prolonged cooking, or by combining these 
factors ; but to sterilize in such a manner as to cause the least injury to the 
