to OK***'*' * R» ^to v ti-- 
During the course of the second expedition of the Alaska Crab Investiga- 
tion, you are requested to make periodic experimental packs of canned crab 
meat in order that we may have a measure of the quality of the crabs taken 
in various localities and at various times. Mot more than twelve cans 
need be packed for each test, six from female crab and sir. from male crab. 
It is assumed, however, that the crabs selected will be representative of 
the catch at the particular time. For your guidance there is included 
recommendations suggested b r, J. F, Puncochar as a result of his experi- 
mental work during the first expedition. 
Preliminary Handling of Grabs 
It is of utmost importance that crabs to be used for canning be kept 
alive until immediately before starting canning operations, The flesh of 
crab contains certain natural enzymes which cause rapid color changes after 
death. These color changes may begin even before bacterial decomposition 
sets in. Certain Crustacea contain a little ammonia even in the living 
condition and if allowed to die before canning the greater amount that is 
formed b enzymic and bacterial action is responsible for a phenomenon that 
is generally known as "blackening". The most prominent reason for blacken- 
ing is d\ie to the iron in the can which comes in contact with the product 
and as a rule shows up along the corners and in the scams of the can "here 
the liquor as well as the underlying tin is pulled apart by contraction and 
expansion during the hoatin * and cooling operations so as to expose the iron. 
If enough ammonia is present, water soluble sulfides contained in the flesh 
will combine with the iron in the can and start the formation of black iron 
sulfide which has a strong coloring power and shows up as a black ring on 
the parchment paper and product. 
A "blue” discoloration of crab meat has oftentimes been noted. It is 
believed that this is due to the presence of copper (haemocyanin) in the 
blood of crustaceans. The copper combines itself with the earlier mentioned 
sulfides and in the presence of ammonia forms a blue-colored copper compound. 
This appears as a deep blue coloring inside the white musculature and in the 
legs and claws of crabs after cooking. Therefore, as a precautiohary measure 
against abnormal discoloration of canned crab meat, only live crabs should be 
used. 
Gleaning and Bolling 
The crabs are butchered while alive. The carapaces (shells), viscera, 
and gills are removed and the carcasses are washed with water under pressure. 
It is believed that this procedure facilitates bleeding and reduces the danger 
of a blue spotted discoloration. After cleaning and washing, the carcasses 
are boiled in either a weak brine (3 percent salt) or in fresh water for from 
15 to 17 minutes from the time the water starts to boil after placement of 
the carcasses into the cooking vnt. After boiling, the crabs should be 
Immediately cooled for about 30 seconds in fresh water or weak brine (3 
percent). This practice will loosen the meat from the shell so that it can 
be more readily removed. 
