Thus, although the tuna processed without precooking contains more 

 natural tuns, oil, the total amount of oil (after absorption of vege- 

 table oil during retorting) (table 75) is less. Thus the amount of 

 vegetable oil absorbed in the tuna from fish which has not been pre- 

 cooked must be a great deal less than that in the normal pack. 



Although the tuna retorted without precooking contained six times 

 as much aqueous liquid as the normal pack, this fact is not readily- 

 apparent when a can is opened. There is always a sufficient excess of 

 oil floating at the surface of such cans so that the aqueous layer, 

 near the bottom of the can, would not ordinarily be noticed. 



A series of penetrometer readings were made on the experimental 

 samples prepared from tuna precooked to different extents (table 78). 

 The greater the length of precook, the more tender was the texture of 

 the fish. The differences (9.96 for no precook, 10.48 for one-half 

 of normal cook, and 10.92 for normal cook), although not numerically 

 large, represent a definite difference which is easily detectable 

 organoleptically. 



Effect of Packing Methods on the 

 Quality of Solid Packed Tuna 



Before the introduction of machine packing, solid-pack tuna was 

 put up very carefully by hand. A good hand-pack contained three pieces 

 of fish tightly filled into the can without any voids between pieces. 

 The action of the guillotine prior to filling out the loins cleanly 

 giving a very smooth-cut surfajce. When these hand-packed cans were 

 retorted, some shrinkage took place, but the tightness of fill before 

 retorting was sufficient to prevent development of any appreciable 

 spaces between pieces. When such a retorted can was opened, the appear- 

 ance was almost as if one piece of fish had been filled into the can, 

 with only faint lines showing between pieces. 



Machine packing has caused several alterations in the appearance of 

 the canned product which may be considered ty experts to be adverse 

 changes. (These alternations apparently have not effected the price of 

 the ma chine -pa eked product nor its consumer acceptance.) These changes 

 involve (l) presence of spaces between pieces in the machine-packed 

 fish, (2) presence in some cases of a large number of pieces in a can, 

 (3) distortion of the fibers of the cut loins, causing sane flaking, 

 and (4) adsorption of oil caused by (l), (2), and (3) above. 



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