FISHERY BULLETIN: VOL 77, NO 



Lot 1 only. Analyses for dimethylamine (DMA), 

 trimethylamine oxide (TMAO), and formaldehyde 

 (FA) were conducted on Lot 2 only. Analyses for 

 total volatile acid (TVA), trimethylamine (TMA), 

 total nitrogen, total solids, chloride, extractable 

 protein nitrogen (EPN), and nonprotein nitrogen 

 (NPN) were conducted on both lots. 



Fish in Lot 1 were held on a sorting table until 

 arrival at the laboratory 6 h later. Ambient air 

 temperature was about 4° C. Pollock and cod were 

 separated from the rest of the catch, individually 

 weighed, tagged, and transferred to the previously 

 described ice or MRSW systems (Bullard and Col- 

 lins 1978). To simulate a commercial operation, 

 the pollock and cod were not segregated by species 

 within the holding systems. This paper deals with 

 pollock; cod will be discussed in a subsequent arti- 

 cle. At regular intervals up to 15V2 days, pollock 

 were selected in such a manner that the average 

 weight per fish in a particular sample was close to 

 the average for all the pollock (495±175 g SD). 

 Each sample from the ice system consisted of 1.3 

 fish and each sample from the MRSW system con- 

 sisted of 14 fish. 



Prior to loading with fish, carbon dioxide was 

 injected into the refrigerated brine until the pH 

 leveled off at 4.3. Subsequent intermittent addi- 

 tion of carbon dioxide kept the pH between 5 and 6 

 throughout the experiment. Temperature was 

 maintained at -1° C. The brine to fish ratio was 

 1.5:1. In the ice system, the fish were mixed in a 

 fivefold excess of ice and fresh ice was added as 

 necessary to replace melted ice. Great care was 

 taken to insure the fish did not touch each other. 

 Although commercial icing conditions are not as 

 thorough, this procedure was used so the data ob- 

 tained would be based on ideal icing conditions. A 

 control sample was taken 6 h after arrival at the 

 dock. 



After removal of a sample from a holding sys- 

 tem, the fish were washed briefly to remove slime 

 or ice, drained on a rack for 5 min, and the weight 

 of the individual fish recorded. The fish were 

 filleted by hand and the fillets were rinsed briefly, 

 drained on an inclined screen for 5 min, and 

 weighed. Notes were made on the appearance of 

 the round fish and the condition of the gills, fillets, 

 and viscera. The fillets were then ground using the 

 coarse blade on an Oster'-^ food grinder. A compos- 

 ite of 800 g was frozen at -34° C. The remaining 



^Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



ground flesh was washed with cold water ( 1 flesh:2 

 water) for 15 min on a reciprocating shaker. The 

 flesh was drained for 30 min on an inclined 16- 

 mesh plastic screen, then weighed and frozen at 

 -34° C for later analysis. All analyses were com- 

 pleted within 2 mo and we assumed no changes 

 took place during frozen storage. 



Formal Sensory Evaluation 



Pollock (Lot 2) were separated from the rest of 

 the catch and stored on the deck of the boat. The 

 fish were frequently sprayed with fresh seawater 

 to keep them cool. About 6 h after capture, the fish 

 were transferred into the ice and MRSW holding 

 systems. A control sample was taken at this time. 

 The icing was less thorough than in Lot 1. Tem- 

 perature and pH of the MRSW holding system 

 were maintained at the same values as in Lot 1. At 

 regular intervals, fish were removed from each 

 holding system and filleted by hand. About 7 kg of 

 fillets were frozen as blocks in plastic bags at -34 

 C for formal sensory evaluation. The remaining 

 fillets were ground and stored at -34" C for later 

 chemical analysis. Chemical and sensory analyses 

 were completed within 2 mo. The last sample ( 12 

 days) was not large enough for the taste panel test 

 and was evaluated by chemical methods only. 



The blocks were sawed into portions measuring 

 80 X 50 X 12 mm and thawed at room tempera- 

 ture. The control sample and samples from fish 

 held in ice were salted by immersion in a 5% NaCl 

 solution for 1.5 min. The portions were cooked in 

 individual sealed aluminum pans at 232° C for 20 

 min in a commercial oven. Because of the difficulty 

 in equalizing the salt content, samples from the 

 two holding systems were not directly compared. 

 Judges were asked to note if a sample were too 

 salty. The results of the sensory tests were 

 evaluated by analysis of variance. If analysis of 

 variance indicated a change had occurred with 

 time of holding, the Student-Newman-Keuls test 

 was used to determine which samples were differ- 

 ent. 



Chemical Analyses 



The frozen samples were tempered overnight in 

 a refrigerator at 3° C and ground twice using the 

 fine blade of an Oster food grinder. Analyses were 

 carried out for total nitrogen, total solids, chloride 

 (Horwitz 1975), total volatile acid (TVA, 



482 



