FISHERY BULLETIN: VOL. 77 NO 4 



in an equal, gradual and linear manner with time 

 of holding in both systems. DMA values did not 

 change with time of holding or system (0.3 mg 

 DMA-N/100 g). 



Effects of Washing Minced Flesh 



Washing the minced flesh of black rockfish re- 

 sulted in a reduction in salt and solids content 

 (Table 1), in slightly lower EPN values (Table 4), 

 and a big drop in TMAO content (Table 5). Wash- 

 ing increased the apparent yield of minced fillets 

 from 32 to 38% (ice) and from 32 to 33% (MRSW). 

 When yield data of fillets and minced, washed 

 flesh are placed on a comparable basis by convert- 

 ing to a salt-free, constant 18% solids basis how- 

 ever, the washing procedure reduced the yield in 

 both systems from 34 to 28%. 



Frozen Storage 



A number of research papers have been pub- 

 lished on the general subject of toughness of fish 

 flesh and the relationship (or not) of free fatty 

 acids, formaldehyde, and EPN (Mills 1975). The 

 tough texture that develops in frozen fish is always 

 accompanied by a decrease in EPN (Castell et al. 

 1973) but texture and EPN are not necessarily 

 equated. It is generally accepted that reduced 

 EPN occurs with increased fatty acid content and 

 formaldehyde content (sometimes indirectly mea- 

 sured as DMA). The extractable protein nitrogen 

 (Table 4) of minced flesh from ice-held fish de- 

 creased slightly at 2 and 4 mo of frozen storage, 

 decreased to about 50% at 6 mo, and decreased to 

 about 35% at 9 mo. The same general trend was 

 observed with MRSW-held fish except EPN values 



Table 4. — Change in extractable protein nitrogen content (percent) of minced flesh (unwashed 

 and washed) from black rockfish ( Lot 1 ) with time of holding in ice and in modified refrigerated 

 seawater. 



Tables. — Change in trimethylamineoxidecontentlmilligramsTMAO-N/lOOgI of minced flesh 

 (unwashed eind washed) from black rockfish (lx)t 1) with time of holding in ice and in modified 

 refrigerated seawater. 



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