712 U. S. BUREAU OF FISHERIES 



of the oil raised. Data obtained on methods of drying press cake 

 indicate that the present method of drying causes an actual loss of 

 material and, no doubt, decreases the potential feeding value of the 

 finished product. Further studies on drying show that by drying 

 the material in a continuous steam dryer of relatively high capacity 

 for this type of equipment, the value of the meal obtained from a 

 similar quantity of fish can be increased about 6 per cent. This 

 increase is due to the elimination of dust losses, and the reduction of 

 distillation and burning losses by drying at lower temperatures. In 

 addition the quality of the meal has been raised, according to pre- 

 liminary feeding tests, and the product is capable of demanding a 

 higher price and should cause an increase in the demand for this type 

 of material. 



Considerable attention was also given to the matter of proper stor- 

 age conditions aboard vessel and at the factory. At the present time 

 vessel operation is not efficient on account of the many trips to the 

 factory where small catches of fish are brought in at little or no profit 

 in order to prevent their spoilage before being reduced. In order to 

 prevent additional spoilage at the factory, the plant capacity is such 

 that the fish may be reduced within a few hours after their arrival. 

 This necessitates high-capacity equipment and a large amount of 

 labor that is only used for a few hours each day. Idle machinery and 

 laborers increase production costs. Studies were conducted on the 

 keeping qualities of fish at various temperatures. The results show 

 that fish chilled to and maintained at temperatures between 35° F. 

 and 40° F. are in as good condition for reduction purposes after five 

 or six days storage as fish handled by present methods after only 

 24 hours. 



A complete report of the bureau's study of the menhaden industry 

 is being prepared for publication. 



REDUCTION OF WASTE FROM NONOILY FISH 



During the past year the bureau continued its studies of methods 

 of reducing the waste from nonoily fish. This type of waste contains 

 a considerable amount of glue material, which causes sticking within 

 the dryer and forms an insulating coat of material on the inner surface 

 of the drying chamber. Most operators overcome this difficulty by 

 using a wet process in which the material is cooked and pressed before 

 drying is attempted. In doing this, much of the gluey material is 

 eliminated and the difficulty of drying is reduced. This procedure 

 makes it necessary to cook and press the material and causes a loss 

 of protein material in the press liquors. The bureau's studies have 

 shown that the material can be handled with some success in one 

 operation, if dried under considerably reduced pressure. To eliminate 

 the sticking, however, it was found necessary to reduce the size of the 

 initial charge and have scraping blades on the agitator come in direct 

 contact with the dryer walls. This latter eft'ect was accomplished by 

 having the scraper blade forced ahead of the agitator paddle and held 

 against the inner walls of the dryer by means of strong springs. The 

 spring blade arrangement allows for contraction and expansion of the 

 metals due to changes in temperature. While these results show 

 some improvement, they are not entirely satisfactory since capacity 

 has necessarily been sacrificed and horsepower requirements increased. 

 Further work on this problem is contemplated. 



