104 DESCRIPTION OF IMPORTANT FISHERIES AND THEIR PRODUCTS 



ing a constant product within its own established style-price-quality field. 

 For this reason the grading procedures used are of great importance. 

 Each cannery has its own method of evaluation and standards. Among 

 commercial requirements color is commonly regarded as being most 

 important, but texture, particle size, flavor, general appearance, and 

 other factors are also judged. 



Development and Outlook 



The basic outline of the tuna canning operation has remained unchanged 

 from that of early days. The only important advances have been the 

 elimination of exhaust boxes, the use of mechanical conveying, filling, 

 and more efficient use of by-products. 



Various alternatives have been proposed to improve the product and 

 the process. Borg"^ describes a canning method in which cans containing 

 pieces of edible portions of the raw fish are immersed in hot water to 

 coagulate the protein, followed by cold water before pressing or centri- 

 fuging to remove the excess liquor. The cans are then oiled and processed 

 as usual. Lang^^ proposed a precooking method in which the fish is 

 sprayed with recirculated cooking liquor during cooking and then cooled 

 in a humid atmosphere to reduce surface drying and oxidation. The 

 'Tauley Process"^^ was used on a hmited scale for some time, but for 

 various reasons was discontinued. This method comprised preparing 

 cleaned skinless, boneless fillets of tuna, precooking to a center tempera- 

 ture of 130°F, then cooling with water sprays prior to cutting to size 

 and packing. The patent authors claim that their method reduces time, 

 loss, and waste. Perhaps the main problem involved in this and similar 

 processes is lack of a mechanical device which will fillet raw tuna cleanly 

 and yet avoid waste. The present precooking system allows a c^uicker 

 and more exaq-'^^eparation. However, Anderson et al.,^ recently proposed 

 a method of separating raw fish into four fillets. Steam is applied through 

 rows of hollow needles along the planes of natural cleavage to beheaded, 

 eviscerated fish. This softens the fish at these points only so that the 

 four quarter fillets can be broken away from the backbone. The skin may 

 then be removed from the fillets with superheated steam before cooking. 



There can be little doubt that, in spite of the present high level of 

 efficiency, much can be done to improve many phases of handling and 

 processing tuna, both at sea and in the plant, which would result in a 

 higher and more uniform quality product. It is probable also that ulti- 

 mately it will be possible to automate processing with a corresponding 

 cost reduction. Meantime the steady per capita increase of consumption, 

 which has been sustained for many years, indicates a continued healthy 



