Study on the Green Meat of Tuna-I

Quantitative Differences of Vitamin B Group and Minerals between the Green and the Normal Meat of Precooked Tuna

Abstract

“Greening” is a term referred to a phenomenon which makes tuna meat discolor into a disagreeable greenish brown as is often met with the meat precooked for canning.
A few investigators, reporting the independency of this phenomenon on either of the method of catch and the degree of freshness, have assigned its origin before to some individual abnormality inherent to the fish in question. Any further information, however, has not been presented thereafter about the nature of the origin of “greening”.
The authors, now, considering some anomaly in vitamin B group and minerals in muscular system for the cause of the greening, measured their quantities in both greened and normal samples of yellowfin tuna. From the results may be formed the following summary:
In comparison with normal meat, green meat is rich not only in moisture but in B₁₂ and poor in B₆. As for the contents of riboflavin, folic acid and pantotheic acid no striking contrast prevails between the two types of meat (Tables 1 ?? 2, Figs. 1 ?? 3).
Nevertheless, it may be worthy of note that, while for normal meat little positive relation can be found between the contents of riboflavin and folic acid, these two vitamins vary in amount in a distinct correlation with each other in greened meat (Table 3).
The amount of mineral constituents seems to be independent of the degree of greening, but it should be remarked that two samples of green meat showed an extraordinary low level of phosphorus content.
These findings will provide a clue to the resolution of biochemical causes of the greening.