glycolytic degradation products in the raw muscle and canned product of skipjack tuna. 



Treatment 



Free fructose 



Raw 



Can 



Free ribose 



Raw 



Can 



Pyruvic 



Raw 



Can 



Lactic 



Raw 



Can 



Live fish, 0° brine . . . 0.88 



32° F-R-F 0.55 



32° F-R-UF 0.81 



32° F-control-R L16 



32° F-S-F 0.56 



32° F-S-UF 0.55 



32° F-control-S 0.44 



78° F-R-F 1.08 



78° F-R-UF 1.28 



78° F-control-R 1.51 



78° F-S-F 1.16 



78° F-S-UF 1.17 



78° F-controI-S 0.53 



60° F-R-F 0.62 



60° F-R-UF 1.22 



60° and 78° F (9) . . . 



control-R 0.80 



60° F-S-F 0.87 



60° F-S-UF 0.67 



60° and 78° F (9) . . . 



controI-S 1.00 



78° F (9)-R-F 1.36 



78° F {9)-R-UF 1.37 



78° F (9)-S-F 0.94 



78° F (9)-S-UF 0.98 



Frozen control-R .... 0.71 



Frozen control-S .... 1.38 



2.22 

 1.73 

 2.31 



2.31 

 2.21 

 1.82 

 2.01 

 2.24 

 1.56 

 2.21 



0.68 

 0.96 

 0.46 



0.85 

 1.12 

 1.21 

 1.40 

 0.66 

 1.40 

 1.43 



1.34 

 0.83 

 1.43 



1.40 

 0.83 

 0.71 

 0.90 

 0.83 

 0.88 

 0.89 



0.10 

 0.11 

 0.08 



0.12 

 0.08 

 0.09 

 0.08 

 0.09 

 0.12 

 0.12 



0.27 

 0.24 

 0.19 



0.28 

 0.21 

 0.19 

 0.18 

 0.18 

 0.25 

 0.25 



132.5 

 144.6 

 138.0 



110.0 

 152.0 

 156.5 

 136.5 

 147.4 

 155.7 

 169.8 



124.4 

 118.4 

 124.4 



105.3 

 128.3 

 109.2 

 127.7 

 141.9 

 117.9 

 126.1 



fiM/g in the raw muscle. In general, the GP 

 content was higher in the unfrozen rested con- 

 trols than in the stressed. The frozen controls 

 had a higher content than the rested. 



The GP content was higher in the unfrozen 

 than in the frozen stressed and rested fish for 

 all treatments except for the controls and for 

 the stressed fish held for 6 hr in 78° F SW 

 where the reverse was true. This observation 

 seems to indicate that freezing may very well 

 destroy or partially desti'oy the enzymes needed 

 for the formation of GP. 



The GP content of the canned products 

 showed a marked decrease (with but one ex- 

 ception) to less than 1 jU,M/g regardless of the 

 content of the raw tissue. This indicates that 

 GP is degraded and probably participates in 

 browning reactions as previously reported. 



Fructose phosphate, fiu/g. — Fructose phos- 



phate (FP) content varied from 0.4 to 6.3 fiM/g 

 in the raw tissue. In general, the observations 

 for this sugar are the same as those described 

 for GP. The FP content of the can decreased 

 to less than 0.5 fiu/g, thus indicating degra- 

 dation. It is probable that this compound par- 

 ticipates in browning reactions. Some evi- 

 dences of this have been obtained by Olcott 

 (unpubhshed). 



Free fructose, /xM/g. — The free fructose con- 

 tent varied from 0.4 to 1.5 fiu/g in the raw 

 muscle. It was surprising to find free fructose 

 in that the author had not found measurable 

 amounts of free fructose before. The signifi- 

 cance of this discrepancy is not known. 



Higher levels of free fructose were found 

 in the canned product, perhaps resulting from 

 the degradation of fructose phosphate. 



17 



