FISH MEAL AND OIL 



483 



The "stickwater" from the meal and oil separation is collected in a receiving 

 tank. The size of the plant controls the capacity of the tank. When the receiving 

 tank is full, the "stickwater" is pumped into iron storage tanks for further treat- 

 ment. During the filling of the storage tanks a predetermined quantity of sulfuric 

 acid is added slowly until a pH of 4.5 is reached. Normally the "stickwater" has a 



1 AcidiHcaiioa tanks 



2 Acid task 



Sopei-D-Caatei 



Heatei 



Nozifectot 



Stabilized stick 

 watei storage 



7 Ttiple-eiiect 

 evapezator 



8 Condensed FisK 

 Solubles stetage 



{Courtesy Sharpies Corp.) 

 Fig. 22-10. Flow sheet for the Sharples-Lassen stickwater process. 



pH value of 6.0 to 7.0. The condition of the original fish and the length of time 

 required for processing are reflected in the pH of the "stickwater." 



The storage tanks are fitted with steam coils and the temperature is held 

 at 150° F (66° C) for 30 minutes to complete the coagulation of some of the 

 proteins and the precipitation of the enzymes. When this reaction is complete, the 

 "stickwater" contains approximately 5 per cent protein in solution, which is re- 

 covered during concentration. 



After the above manipulation the stickwater is passed through a clarifying centri- 

 fuge to remove all of the precipitated solid. During this centrifuging a small 

 amount of oil, approximately 1.0 per cent, which has probably been entrapped 

 mechanically by the suspended protein, is recovered. It has been estimated by 

 some operators that the oil recovered at this point is of suflBcient value to pay for 

 the centrifuge during 1 year's operation. This, however, would depend upon a 

 number of factors, and probably cannot be accepted by all operators, or for all 

 species of fish. The oil recovered from the acidulated stickwater is usually a 

 darker color than that recovered from the original press liquor; it is generally used 

 for blending with other oils, or marketed as a lower grade. The stickwater from 



