FISHERY BULLETIN VOL 77. NO 2 



equal lengths of time in (different holding systems, 

 but were almost absent in the cooked samples 

 (Table 2). The flavor scores of iced pollock did not 

 change significantly until after 6 days and texture 

 remained unchanged throughout the experiment. 

 Kramer et al. ( 1977) reported that pollock can be 

 held 12 days in ice with only a small decrease in 

 flavor scores and none in texture scores. The pol- 

 lock used in that experiment were larger than 

 those used in our work, and preparation and cook- 

 ing of the fish were different. 



The flavor scores for the MRSW samples re- 

 mained unchanged to 4 days and were acceptable 

 to 8 days except for the high salt content. The 

 increased salt content, in addition to the develop- 

 ment of a disagreeable taste noted by some panel 

 members, was probably the reason sensory scores 

 decreased after 4 days in MRSW. The scores for 

 texture remained unchanged throughout the ex- 

 periment. 



These conclusions on holding characteristics of 

 pollock were based on fish obtained from one loca- 

 tion at one time of year but pollock caught at 

 different locations may have different holding 

 properties (Kramer et al. 1977). Not only does the 

 size of walleye pollock vary from one location to 

 the next (Kizevetter 1973) but there is some evi- 

 dence of distinct breeding groups (Iwata 1975). 

 Variation due to the yearly reproduction cycle 

 may also affect the holding qualities. 



16.57f in either system for both lots. The nonpro- 

 tein nitrogen content was 1 W of the total nitrogen 

 content initially and did not change with time of 

 holding in ice but slowly decreased to 79; after 10 

 days in MRSW. The free a-amino-nitrogen content 

 did not change significantly during the experi- 

 ment, averaging 7.1 ±0.7 (SD) and 6.2±0.9 (SD) 

 mg N/100 g sample in the fillets offish held in ice 

 and in MRSW, respectively. 



Several chemical analyses were performed to 

 determine which, if any, could be used as an index 

 of spoilage. TVB changed little and never ex- 

 ceeded 10 mg N/100 g sample making it unsuit- 

 able as an index of spoilage. Tokunaga (1964) re- 

 ported TVB values of 10-13 mg N/100 g sample for 

 freshly caught pollock. Analysis for TVA in fish 

 from Lot 2 gave values essentially the same as in 

 Lot 1. Except for the 2.5-day sample, values for 

 TVA content of ice-held fish remained largely un- 

 changed at <0.20 meq H'/lOO g flesh to 4.5 days 

 but then began to increase (Figure 1 ). The increase 

 at 4 days coincided with the change in quality as 

 determined by informal subjective evaluation of 

 the raw fillets but preceded by at least 2 days the 

 decrease in flavor scores of the cooked fillets. 

 Therefore, TVA content could be used as an index 

 of spoilage for pollock held in ice if supplemented 

 by subjective sensory examination of cooked fish. 

 For MRSW-held samples, a rapid increase in TVA 

 content occurred after 12 days while a significant 



Chemical Analyses 



While the salt content of pollock held in ice 

 remained relatively unchanged with time of hold- 

 ing, it increased rapidly in MRSW-held fish (Table 

 1 ). Salt contents offish from both lots were similar. 

 The protein contents (6.25 x <7c total N) of the 

 fillets varied little with holding time and averaged 



Table 2. — Change in mean sensory analysis scores for baked 

 portions of blocks of fillets of walleye pollock (Lot 2) with time of 

 holding in ice and m modified refrigerated seawater i MRSW). SD 

 are in parentheses. Panel had 12 judges. Flavor and texture 

 scores were on the following scale: Very good, 5; Good, 4; Fair, 3; 

 Borderline, 2; and Poor. 1. 



Time o( 



Flavor 



Percent 



responding 



too salty 



'Values viiltl aslerisl* were signiticanlly (P - 05) diHerent Irorn zero holding 

 time values 



8 10 1 .:> 



HOLDING DAYS 



FIGURE 1.— Change in total volatile acid iTVA I content of fillets 

 from walleye pollock (Lot li with time of holding in ice and in 

 modified refrigerated seawater (MftSWi. 



484 



