FISHERY BULLETIN: VOL. 69. NO. 2 



concentration of CO2 in the flesh (842 ppm) was 

 reached at this time. 



The retention of CO2 in the flesh was given 

 consideration as a potential problem in contrib- 

 uting to an abnormal head-space pressure in 

 canned salmon and to the separation of breading 

 on breaded rockfish products. The initial indi- 

 cations were, however, that the retention of CO2 

 will not be a problem. As was remarked earlier, 

 CO2 is not absorbed well at above-normal storage 

 temperatures. CO2 will therefore likely be dis- 

 sipated from the flesh during routine cleaning, 

 heading, and washing operations, which are done 

 at temperatures considerably higher than those 

 of storage. In an experiment in which red salm- 

 on were held in modified refrigerated natural 

 seawater and commercially canned, no problems 

 were encountered as the result of CO2 retention. 

 In canned products such as tuna and shrimp, the 

 retention of CO2 should not be a problem, be- 

 cause these products are exposed to relatively 

 high preprocessing temperatures. 



Additional consideration of these potential 

 problems, however, will be given to the retention 

 of CO2 in future studies on modified refrigerated 

 brine. 



Salt concentration. — The concentration of so- 

 dium chloride was measured by the method de- 

 scribed by Greig and Seagran (1965) . In brief, 

 a plastic-strip indicator containing a sensitized 

 capillary element was placed in a filtered extract 

 of fish and distilled water. After the reading 

 was taken by means of the indicator, the con- 

 centration of salt in the extract was read from 

 a standard curve supplied by the manufacturer 

 of the device. 



During the first 8 days of storage, the uptake 

 of salt was similar in the fish held in treated 

 brine to that in the fish held in the control brine. 

 Concentrations of salt in the fish held in the un- 

 treated brine for longer than 8 days were not 

 determined, because these fish spoiled at about 

 that time. The fish held in the treated brine 

 were analyzed for concentration of salt on the 

 10th and 17th days of storage. They showed 

 somewhat more uptake of salt at each of these 

 times. 



SUBJECTIVE MEASUREMENTS 



Raw Rockfish 



At each sampling, a trained taste panel de- 

 termined the eff'ect of storage of the fish in two 

 kinds of brine water. The fish were also eval- 

 uated in the round for general appearance and 

 odor. 



During the first 3 to 4 days of storage, fish 

 held in either of the two brines were of good 

 color, odor, and texture. By the 5th day, odors 

 occurred in the fish held in the untreated brine. 

 Between the 7th and 10th days, the fish were 

 judged, by appearance and odor, to be unfit for 

 tasting. During this time, the untreated brine 

 had a strong odor of putrefaction and was dark 

 brown. 



The fish held in brine treated with CO2 re- 

 tained good color, odor, and texture for 17 days. 

 The brine was almost colorless and odorless at 

 the end of the experiment. 



Cooked Rockfish 



Cooked rockfish were prepared for taste-panel 

 evaluation by the method of Miyauchi, Stoll. and 

 Dassow (1964). The samples of cooked fish 

 were evaluated for appeai'ance, odor, flavor, tex- 

 ture, and overall quality, using a 10-point nu- 

 merical scale. 



Table 2 gives the sensory scores for the cooked 

 samples. The data show that the fish in the 

 untreated brine spoiled between the 7th and 

 10th days of storage. Except for an increase 

 in saltiness, which occurred in the fish in either 



Table 2. — Sensory evaluations on the cooked flesh of 

 rockfish held in COo-treated refrigerated brine and un- 

 treated brine (control). 



' A score of 10 denotes a product of highest quality,- one of 5 denotes 

 a product of borderline quality. 



438 



