THE PRESERVATION OF FISH BY SMOKING AND DRYING 



403 



The humidity may be controlled to a limited extent by regulating the smoke 

 generator, the temperature within the smokehouse, and the air circulation, and by 

 adjusting the exhaust dampers. The efficiency of these operations is dependent 

 upon external atmospheric conditions. In moist atmosphere it will be necessary to 

 remove moisture from the air before it enters the smoking chamber. This is ac- 

 complished by installing a cooling system ahead of the air intake. Warm air can 

 hold more moisture than cold air. The indrawn air is first passed over cold coils or 

 chopped ice to remove most of the moisture. This cold dry air must be preheated 

 before entering the smoking chamber. The smoke unit should be equipped with 

 an exhaust damper to allow for the removal of moisture-laden air. 



Air-smoke velocity and distribution within the smoking chamber are very im- 

 portant factors in the proper curing of fish. The preliminary drying air and the air- 

 smoke mixture velocities can be controlled by a variable-speed volume blower or 

 fan. Louvers should be located at proper positions to direct an even flow of 

 air-smoke through the smoking chamber. Damper control aids in the removal of 

 excess air, smoke, and moisture and also recirculates smoke to prevent waste. 

 Proper air-smoke distribution eliminates the so-called "banding" or uneven curing 

 of the product. Air velocity must not be too great, otherwise heat is wasted and 

 excess drying of the product results. In this connection it is important that the 

 smokehouse is not overloaded or the fish arranged so as* to prevent suitable circula- 

 tion of the smoke. 



In general a smokehouse embodying the principles of controlled smoking should 

 be designed so as to be adaptable for any type or form of fish or fishery product. 

 Installation of automatic temperature and humidity indicators is desirable. Auto- 

 matic control of chamber temperature is an advantage, and manual control of 

 air velocity, smoke density, and dampers is suitable. 



Volume blower 



Rodiotors -. 

 Air smoke intake 



Recording 

 psych rometet-*- 



Dompe 

 control 



^Air exhaust 



^Domper 



Battles 



Fig. 19-2. Diagram of controlled smokehouse designed by C. L. Anderson indicat- 

 ing path of smoke. 



