or: 



This panel and industry experts (Crawford 

 et al. (1970) , whose experience with skipjack 

 of this degree of freshness was limited, may 

 have been conditioned to accept standards 

 of freshness less than that achieved here 

 (heretofore, controls were captured at sea 

 some distance from the cannery and frozen 

 at some low temperature to preserve its 

 freshness until such time as it could be pro- 

 cessed upon arrival at the cannery) . 



In any case, these observations disagree with 

 those reported by Crawford et al. (1970) 

 where the controls (rested) received near per- 

 fect odor and flavor scores. It has been sug- 

 gested by the Hawaiian Tuna Packers (Hono- 

 lulu, Hawaii) that this phenomenon may be 

 attributed to seasonal variations (winter- vs. 

 summer-caught fish) . Other conflicts in results 

 with those reported by Crawford et al. (1970) 

 tend to support this contention. This suggests 

 that diff'erent quality parameters may be ap- 

 plied and that diff'erent handling procedures 

 may be required for each seasonal catch, at least 

 for the skipjack caught in Hawaiian waters. 

 In general, none of the treatments produced 

 cans of skipjack that were of excellent overall 

 quality. However, there were some packs that 

 were of fairly poor overall quality. The packs 

 that were of fairly poor overall quality were 

 those held for 6 hr in 32° F RSW and 78° F SW 

 (stressed frozen, and unfrozen) and the fish 

 held for 9 hr in 78° F RSW (all treatments) 

 and to some extent, the controls. The stressed 

 fish show a tendency to have more off flavor and 

 poor color than the rested for each treatment 

 (except for the controls). However, the dif- 

 ferences between the two are slight and are 

 not sufficiently discernible to be of any com- 

 mercial value. A fairly good overall quality 

 pack was produced from the rested fish held at 

 32° F; the other packs of tuna were of fair 

 quality. 



CONCLUSIONS 



Skipjack tuna were sacrificed in a rested and 

 stressed condition. Some were canned imme- 

 diately to serve as controls. Others were held 

 in 32° F RSW, 60° F RSW, and 78° F SW for 

 6 hr, and some were held in 78° F SW for 9 hr 



before canning. Additionally, an equal number 

 of the fish from all treatments were frozen (for 

 20 hr), then thawed, and canned. Samples 

 were taken before and after canning for mea- 

 surement of glycolytic and purine degradation 

 products. Organoleptic evaluations were made 

 on the canned product. This experiment was 

 designed to show if there were any differences 

 (biochemical or organoleptic) between stressed 

 and rested skipjack tuna held at various tem- 

 peratures for either 6 or 9 hr. 



There were no commercially discernible dif- 

 ferences between rested and stressed skipjack. 

 The relation of biochemical components mea- 

 sured to the treatment (time and temperature) 

 of the fish and the subsequent relation to the 

 quality of the canned product were not suffi- 

 ciently defined to use for quality predictions. 

 Glucose, glucose phosphate, and fructose phos- 

 phate were some of the sugars measured and 

 were found in relatively large quantities in the 

 raw muscle of the fish (regardless of treat- 

 ment) . These sugars showed marked decreases 

 in the canned product which suggest that they 

 may have been involved in the browning re- 

 actions that were in evidence in the canned 

 product. There was no apparent correlation 

 between the amounts of sugars present and the 

 degree of browning. There were no consistent 

 differences between the lactic and pyruvic acid 

 content of stressed and rested fish. Freezing 

 had an apparent effect upon some of the glyco- 

 lytic enzymes. Purine degradation products 

 were estimated but no significant relations or 

 correlations were established. 



The organoleptic evaluation of the quality of 

 the canned product revealed that none of the 

 packs were of excellent overall quality. The 

 fish held in 32° F RSW (rested) had fairly good 

 overall quality. All other packs were of fair to 

 poor quality. There was some evidence that 

 the stressed fish may be of poorer general qual- 

 ity than the rested. However, this difference 

 was not commercially significant. 



The fact that there were only relatively small 

 differences between rested and stressed fish 

 may be due to the inability to capture a truly 

 rested fish. The "thought" of capture may be 

 sufficient to induce a stressful condition in the 

 skipjack tuna. Capture and sacrifice by elec- 

 tronarcosis or powerful anesthetics might be 

 used to study this further. 



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