CURED FISHERY PRODUCTS 327 



ent in commercial salt, are especially harmful in retarding penetration 

 of the salt into the fish. On the other hand, some of these impurities 

 bleach the fish and yield a whiter product. The temperature of the fish 

 and brine during salting is another important factor. Raising the temper- 

 ature accelerates the rate of penetration of salt into the fish. It also, 

 however, increases the rate of bacterial spoilage. The salt concentration 

 outside the fish is, of course, also an important factor with more rapid 

 osmolysis and removal of moisture taking place at higher salt concen- 

 trations. Tressler^, in studying factors important in achieving rapid salt 

 penetration before onset of spoilage during the salting of fish, found that 

 the method of dressing of the fish is of considerable importance. Removal 

 of all blood is of special importance. 



Smoking. Smoked fish is produced by a combination of salting, drying, 

 and smoking processes. In lightly smoked fishery products, which include 

 the more important varieties produced in the United States, some of the 

 most important changes occur during the salting and drying steps. Thus, 

 much of the increased storage life of lightly smoked fish comes from the 

 preservative action begun during the brining and largely effected during 

 drying before the smoking process begins. The smooth sheen which gives 

 the fish the glossy appearance and results in formation of a surface pellicle 

 is produced during the brining and drying steps. The smoking adds mostly 

 color and flavor except in heavily smoked products where the quantity of 

 formaldehyde, phenols, and other substances deposited on the fish from 

 the smoke may be sufficient to account for an important part of the 

 preservative effect. 



Pickling. In pickled fish the preservative action comes largely from the 

 combined action of the salting, and hence lowered moisture content, and 

 from the much lower pH resulting from the use of vinegar. Pickled fish 

 generally also contain added spices or other flavoring components, and 

 these may contribute some to the keeping quality. 



Processing Salt Fish 



Dry Salt Process. Salt fish are commonly prepared by one of two 

 general methods — the dry salting process or the brine pack process. In 

 the dry salt process, the fish are salted in such a way that the moisture 

 withdrawn by the salt and the brine formed are removed from contact 

 with the fish during or before the end of processing, leaving a fairly dry 

 product which may be further dried by artificial methods. The usual salt 

 cod is an example of this type. In the brine pack process, the brine formed 

 during salting is left in continual contact with the fish until the salted fish 

 are sold or converted to another form. Mild cured salmon and salt mack- 

 erel are of this type. 



