Table 1. --Types and relative heme pigment content in raw and cooked 

 tuna. Basic heme pigment is assumed to be myoglobin 



+ = low concentration 

 + += higher concentration 



significant slight absorption of unknown source 

 was noted at about 480 millimicrons for normal 

 flesh that was present to but a slight extent, or 

 absent, in the curves for green meat. The prom- 

 inent absorption maxima at 530 and 5 60 nnillimi- 

 crons are the peaks characteristic of denatured 

 globin hemochronne, the reduced form of the 

 hemichrome pigment noted in the other cooked 

 samples. The results of these studies on the 

 reflectance curves for green and normal, and 

 the pigments that are indicated as being present, 

 are summarized in table 1. 



It was noted that a copious quantity of yellow- 

 colored leach liquor was obtained during the pro- 

 cess of cooking tuna flesh in the laboratory. Also 

 it was found that a deeper pigmentation was pres- 

 ent in the leachate from the normal tuna than that 

 from the green, indicating some correlation. 

 The leached material was susceptible to oxida- 

 tion with oxygen and reduction with dithionite, 

 but gave no characterizing absorption curve. 

 Attempts to purify by column chromatography 

 were inconclusive. Laboratory cooking of nor- 

 mal and green tuna flesh in contact with leach 

 liquor form normal or green tuna had no effect 

 on the color of the samples. 



CONCLUSIONS 



From the above investigations we have 

 reached the tentative conclusions that (1) the 

 color changes, including greening, that take place 

 in tuna flesh on cooking are the result of reactions 

 of the normal pignnents of the flesh (henno- or 

 myoglobin or their derivatives) with other 

 ingredients of the flesh or with the environment, 

 and (2) at this stage of the work we are inclined 

 to the belief that differences between normal and 

 green flesh lie chiefly in the differences in con- 

 centration of certain of the connnnon heme pig- 

 ment derivatives. Sonne evidence also exists for 

 a low concentration of additional pigments in 

 cooked green meat , which may be unusual hemi- 

 or myoglobin derivatives. Browning and greening 

 seem to be manifestations of oxidation of the heme 



protein pigments. How these pigment factors 

 are related to the physiological or physical con- 

 dition of the fish flesh remains to be investigated. 



LITERATURE CITED 



HUSAINI, S. A., F. E. DEATHERAGE, and 

 L. E. KUNKLE 



1950. Studies on meat II. Observations on 

 relation of biochemical factors to 

 changes in tenderness. Food Tech- 

 nology 4(9): 366-369. 



MACKINNEY, G., and C. O. CHICHESTER 



1954. The color problem in foods. In: 

 Advances in food research 5. New 

 York: Academic Press, Inc., 538 p. 



MATSUZAKA, Y., and N. TAKAHASHI 



MS. Studies onthe green meat of albacore. 

 Mimeographed, undated. 



MIYAUCHI, D. T. 



1950. Some processing and technological 

 methods in the Japanese fisheries. 

 U. S. Fish and Wildlife Service, 

 Comm. Fish. Rev. 12(10): 1-20. 



MONDOVI.B., and E. ANTONINI 



1955. Purification and crystallization of the 

 myoglobin of salt water fish. Arch. 

 Biochem. and Biophysics 58(2): 498- 

 500. 



