FISHERY BULLETIN: \OL, 69. NO. 2 



Figure 2. — ArranKement of the Moyno pump for recirculating chilled brine in the holding tank (on the left) 

 and the CO2 cylinder (in the back) and attached CO2 flow meter (being adjusted by the worker). 



with 180 ml of sterile O.l'^r pe])tone solution at 

 38° F. Serial dilutions in O.l'^.f peptone-water 

 were prepared for pour plates from the homo- 

 genate. Total plate counts were made by use of 

 a TPY medium (0.5'; yeast extract, 1.5'; tryp- 

 ticase, 0.5% phytone, 0.2% glucose, 0.5% NaCl, 

 and 1.5% agar) . Counts were made on the brine 

 by taking 1-ml samples, making appropriate se- 

 rial dilutions in the 0.1% peptone-water mix- 

 ture, and plating out onto the TPY medium. 

 The plates were incubated at 22° C for 5 days. 



Results and discussion. — Table 1 gives the re- 

 sults of the total-])late-count analyses on the 

 brines and on the flesh of the rockfish. The 

 data from the untreated brine show that a lag 

 in bacterial growth occurred during the first 3 



days of the storage test. After the third day, 

 however, the i)oi3ulation of bacteria in the brine 

 increased rapidly. 



Total plate counts made on the brine treated 

 with CO2 did not show a significant increase 

 in the numl)er of bacteria during the 17 days 

 of storage. 



Bacterial growth in the flesh of the rockfish 

 held in the untreated brine was not inhibited 

 during storage. On the 10th day, the fish were 

 judged, by ajjpearance and odor, to be inedible 

 and unlit for testing. At this time, the total 

 ])late counts each exceeded a million organisms 

 lier gram of flesh. (A total plate count of a 

 million organisms iier gram usuallv indicates 

 flesh of poor (luality.) 



436 



