A second result of the pre cook process is elimination of much of 

 the natural tuna oil which is cooked out and discarded. There is some 

 belief that this tuna oil has a strong^ disagreeable flavorc This is 

 true if the fish have been held in cold storage for extended periods 

 of time^ stored at too high storage temperatures or have not been ade- 

 quately protected against access to air^ Under such storage conditions, 

 the tuna oil becomes oxidized, resulting in a rancid flavor, and its 

 elimination during precooking is necessary if a first-class product is 

 to be produced. Ordinarily, if fresh or properly stored tuna are used, 

 a good product without off flavor will result even if the tuna oil is 

 not removed o With some of the darker species of tuna, the tuna oil 

 may, even when fresh, have a distinctive flavor vAiich makes its removal 

 preferable. 



A third result of the precook process is elimination of water to- 

 gether with some dissolved tissue components. Thus, the precooked tuna 

 has a lower moisture content and a hi^er protein contait than the raw 

 fish. Precooking alters the texture of the tuna; the longer the pre- 

 cook the greater the texture difference » After the fish has been re- 

 torted in the cans, however, any texture difference due to precooking 

 is partially eliminated. The retorting process, being carried out at 

 a much higher temperature than the precook, is much more drastic even 

 though the processing time is much less» Normally precooked fish give 

 up very little oil or moisture while being retorted in the can. Raw 

 or under-precooked fish, on the other hand, liberate some of the Juices 

 which would have been cooked out in a thorough precook and, instead of 

 being discarded j, they are retained in the can^ 



Moderate reduction of the precook time has the following results 

 on the final retorted product in the can: 



lo Less of the flavorful juices are discarded (in the precook) 

 and are present to flavor the Ush in the can. This is an 

 advantage to the consumer if fresh, properly stored tuna 

 are used, because the flavors lost in the precook are natural 

 flavors which add to the desirable flavor of the product. On 

 the other hand, this loss would be an advantage to the con- 

 svuner in case the fish were not fresh or had been held frozen 

 for too long a time or under improper storage conditions o 

 Under such circumstances the loss of flavors would be a loss 

 of undesirable constituents which would have altered the flavor 

 of the tuna in a deleterious way. 



314 



