4 BULLETIN 538, IT. S. DEPARTMENT OF AGRICULTURE. 



a hydrometer graduated in salt percentages, Baume scale, or specific 

 gravity. Hydrometer readings should be taken only in cool brines, 

 the temperature of which is as near 60° F. as possible. With these 

 instruments the packer can determine readily by a few experiments 

 the best brine and the best temperature as related to time of cook- 

 ing. Cooking for 15 minutes in a 15 per cent brine might be used as 

 a starting point in these experiments. 



The following table shows the approximate relationship between 

 the boiling points, densities, and specific gravity of the brines, and 

 the amounts of salt needed to make a brine of given percentage. In 

 ordinary practice, however, it is necessary to have from 10 to 20 per 

 cent more than the specified amount of salt. As commercial salts 

 vary in impurities and moisture content, this table is suggested only 

 as a guide. It must be modified after experiment to fit the particular 

 salt used. 



Table 1. — Approximate relationships between boiling points and strength of brine. 





Boiling 



Specific 

 gravity 

 of brine 

 at 60° F. 



Density 



Dry salt 

 required 



Salt. 



point of 

 brine. 



of brine 

 at 60° F. 



for 100 

 gallons ' 

 of brine. 



Per cent. 



°F. 





° Baume. 



Pounds. 



5.0 



214 



1.035 



5.0 



43 



7.5 



216 



1.054 



7.4 



65 



10.0 



217 



1.073 



9.8 



86 



12.5 



219 



1.092 



12.2 



113 



15.0 



221 



1.112 



14.5 



139 



17.5 



223 



1.131 



16.7 



165 



20.0 



225 



1.152 



19.0 



191 



25.0 



228 



1.192 



23.2 



230 



COOKING WITH LIVE STEAM. 



Live steam, occasionally used for cooking headed shrimp that are 

 intended for drying, may also be employed in cooking shrimp for 

 ordinary purposes. The shrimp are sprinkled evenly with salt and 

 allowed to stand a short time. They are then placed in a steam-tight 

 box and subjected to the action of live steam for half an hour. This 

 process, aside from obviating the necessity for making and handling 

 brines, requires less salt, prevents soaking out of flavors, and results 

 in less loss in weight. Where brine is used, chemical analysis of the 

 scums and brines after cooking shows that considerable amounts of 

 albuminous and mineral matter have passed from the shrimp into 

 the brine. The albumin coagulates upon boiling in much the same 

 manner as does the white of an egg. This loss in albuminous and 

 mineral matter means that the shipper loses, since he has fewer 

 pounds of shrimp to ship, and that the consumer does not receive 

 the full food value of the product. 



