400 MARINE PRODUCTS OF COMMERCE 



Smoking. The primary purpose of smoking is to impart to the fish the particu- 

 larly desirable smoked flavor and color. Little preservative action is afforded by 

 the smoking process. Some antioxidants may be imparted to the fat (Stansby and 

 Griffiths, 1943); however, as salting tends to increase the susceptibility to oxida- 

 tion, the beneficial effects of the deposited antioxidants are thereby overcome. 

 The preservative action of the deposited constituents of the smoke is only slight 

 although phenols, aldehydes, and possibly the fatty acids in the concentrations 

 deposited on the fish may serve as mild antiseptics (Shewan, 1945). This inhibi- 

 tive action on bacteria is most effective on the surface of the fish, especially when 

 the smoke concentration and length of exposure are increased (Hess, 1928). 

 It must be emphasized that despite the beneficial effects of brining, drying, and 

 smoking, smoked fishery products are highly perishable and should be held under 

 refrigeration at all times. 



It is believed that the deposited phenols are responsible for the formation of 

 the color of smoked products (Linton and French, 1945). These compounds, 

 usually found in wood smoke, tend to darken to a deep brown color on exposure 

 to oxygen. This then is probably the reaction that takes place after these sub- 

 stances are deposited on the fish dming the curing process. 



For smoking, almost any kind of hardwood, such as oak, alder, hickory, ma- 

 hogany, etc., may be used. Softwoods are not recommended because of their 

 resinous nature and their tendency to deposit acrid flavors and odors on the 

 smoked products (Sidaway, 1944). The quality of the smoke produced by any 

 type of wood may vary considerably with the control of conditions within the 

 smoke generator itself. In general two types of smoke may be produced in a 

 generator-"distilled" smoke and "blown" smoke (Cooper and Linton, 1934). The 

 distilled or wet dense smoke is produced as a result of a low rate of combustion of 

 the wood. This is caused by allowing only a small amount of air to enter the 

 generator during the smoking process. The dense gray smoke contains much 

 moisture and does, thereby, allow for less shrinkage in the smoked fish. This is 

 not necessarily an advantage since some drying of the fish must occur to permit 

 the formation of a suitable pellicle and to yield a smoked product of good quality. 

 The distilled smoke produces a heavy dark pellicle and imparts a bitter, acrid 

 taste to the product since it contains more resinous material and acids. The 

 "blown" smoke is produced by a more complete combustion of the wood. It is 

 a lighter smoke, containing more of the desirable products of combustion which 

 tend to produce a smoked product of good flavor and color. This type of smoke 

 usually contains less moisture and therefore aids in drying the fish. As a result 

 a more suitable pellicle is formed, giving the fish the desirable texture, color, and 

 flavor. 



Other methods of imparting smoke flavor to fish products, such as by the use 

 of liquid smoke flavor and by electrodeposition of the constituents of smoke, have 

 been suggested. Liquid smoke flavors have not proved entirely satisfactory, but 

 may be used for certain particular cases. The process for the electrodeposition 

 of smoke flavor is still in the experimental stage, but is adaptable primarily for 

 imparting smoke flavor to fish products prior to canning. 



The amount of smoke curing applied to the fish is dependent upon the type of 

 product desired and upon the species of fish used. Some fish contain different 

 amounts of oil or fat, and their salting and smoke curing may need to be ad- 



