128 American Fisheries Society. 



to be rendered from them. For example, one hour expos- 

 ure in the dryer to a temperature of 120 degrees Fahrenheit 

 brings about these undesirable changes while one-half hour 

 does not. The fish enter the dryer at or below outside 

 air temperature, say 60 degrees Fahrenheit: and then the 

 temperature near the skin gradually rises towards that of 

 the drying air. During the first 30 minutes the temperature 

 may vary from GO to 100 degrees and during the next 30 min- 

 from 100 to 110 degrees Fahrenheit. It would appear from 

 this example that the undesirable changes take place after 

 the fish attain a temperature of over 100 degrees. The 

 experimental evidence shows this to be the case with fhe 

 limiting temperature possibly a few degrees lower. 



To use the higher temperatures, then, times must be cut, 

 yet it is found that if this is done the total moisture loss is 

 quite the same as at the lower temperatures with their longer 

 drying times. The fish are in excellent condition for frying, 

 too, and do fry perfectly satisfactorily. This angle of the 

 drying problem is a m^ost important one, for it is entirely 

 possible that future study along this line may mean a great 

 deal ; at least the preliminary work gives such a promise. 



Drying conditions being equal, small fish will lose water 

 more rapidly than large fish. The rate of loss in any case 

 varies with the time; the percentage loss being considerably 

 larger during the first unit of time and after that, more nearly- 

 equal for each succeeding unit of time. In no case were fish 

 dried longer than three hours. 



Steamed fish lose water much more rapidly than raw 

 fish ; otherv/ise they behave quite similar to raw fish under 

 different drying conditions. Much research, however, was 

 not carried out on steamed fish ; this to be done later. 



In the California industry where accurate data on com- 

 mercial dryers were collected, temperatures from 75 to 120 

 degrees Fahrenheit and velocities from 350 to 1450 feet per 

 minute were in use. Times varied from 28 minutes to about 

 3 hours, with losses on large fish running from 3.8 to 10.7 

 percent. In all cases fish were being dried for frying in oil. 

 One canner was getting 3I/2 times the efficiency from his 

 dryer that his next door neighbor was and they are both 

 big successful plants. 



Having available data upon the behavior of the fish and 

 knowledge of the role of drying in the preparation of the 

 fish for canning, one is able to make better use of the general 

 principles of drying and their application as embodied in 

 dryer design. This means that present equipment and prac- 

 tices can be made much better and future installations 

 smaller and more efficient than the ones now in use. 



