No. 2 (1921) RExMARKS ON CANNING 127 



tonic than that from oysters, and an invaluable restorative for 

 invalids. 



Tlie general method with clams is to open the shell fish as 

 mentioned above for oysters (paragraph 193), taking care to preserve 

 the natural liquor from the fish ; wash the meats free from all sand, 

 etc., mince or pulp them in a mincing machine, add the liquor and 

 a small quantity of water, boil the mass for an hour skimming the 

 fluid during boiling, press the boiled mass to comparative dryness, 

 and then evaporate the resulting fluid at a low temperative either 

 to a pasty mass or to dryness. Any required condiments may be 

 added to the product, usually when in the fluid state. It would 

 seem preferable to add the natural liquor, previously just sterilized, 

 to the fluid resulting from the pressure of the boiled mass; this 

 would assist in retaining the flavour of the juice which prolonged 

 boiling would impair ; one recipe indeed expressly suggests this 

 later addition of the liquor. 



The fluid should be evaporated at the lowest possible tempera- 

 ture in order to avoid changes caused by heat, e.g., the coagulation 

 and hardening of the albuminous constituents, the loss or alteration 

 of flavour, etc. But since, even with salt, it is a highly putrescible 

 substance, it cannot be slowly dried in the open air; hence it can 

 only be properly desiccated /;/ vacuo. At Beypore there is a 

 vacuum stove which gives a vacuum as high as 27 to 28 inches so 

 that goods can be desiccated at or below 140° F. as a maximum ; 

 this method has been successfully tried there as regards prawns 

 and fish. Abundance of ordinary oysters and other shell fish are 

 available in the various rivers and backwaters, e.g., at Kadalundi 

 ai.d in the Beypore river ; hence the method maybe readily tried 

 for oysters, mussels, etc. 



The desiccated product should then be put up in hermetically 

 sealed cans and sterilized like fish pastes. 



From the above method the resulting product is purely an extract 

 like that of Liebig's " extractum carnis," etc. But in other recipes 

 the whole mass of fish meal or pulp, and juices is desiccated, 

 reduced to powder, and is then combined with some farinaceous 

 substance such as flour, biscuit powder, etc., and with salt, etc. ; 

 this mixed powder forms a highly nutritious food. In two recipes 

 the farinaceous and other additions are made to the pulped mass of 

 clam meat and liquor before desiccation, so as to form a paste or 

 dough which is then desiccated at as low a temperature as possible, 



