It is supposed that there are some relationships between the physico-chemical properties of fish meat paste containing salt and that of the fish jelly produced by steaming the paste. The authors have devised four laboratory tests by means of adhesive power and resistance on push-in for the paste1), and depression- and breaking-strengths for the jelly2).
For the test, an amount of meat from the great blue shark, prionace glaucus LINNE, was divided into a few groups of samples and left to stand for lengths of time to let them deteriorate to different extents.
Each sample was in turn processed into paste in a strictly uniform manner which included chopping, adding 2.5 par cent of NaCl, and grinding it up. After taking the measurements stated above, the paste was turned to a fish jelly by steaming for 20 minutes. Then measurements of depression and breaking strengths of it.
The results from measurements of all the samples revealed that adhesive power and resistance on push-in of the paste decrease in accordance with deterioration of material meat, and that strengths in depression and breaking weaken in parallel with the above decreases.
A series of hypotheses on the mechanism of variation in physico-chemical properties of the products have here drawn out of discussion on the properties in relation to chemical deterioration of muscle proteins. When the chopped fish meat is ground with salt (NaCl), the muscle proteins seem to transform from a gel into a sol and acquire a marked stickiness. That adhesive power of the paste decreases with the deterioration of material meat is attributable to the denaturation of myosins, and thus to the decrease in the amount of myosins dispersing in the paste. As a result, the paste, when turned into a jelly after heat coagulation, would be more or less prevented from forming a well developed structure of network. The last may explain variation in jelly strengths.
On standing the sticky paste falls into “setting” which was found to take place as the loss of stickiness and as the increase in elasticity.
When the curve in Fig. 3 are examined, modes of the setting may be classified into three types which are likely associated with different grades in freshness of material meat. Chmeical explanations given to this fact have come in harmony with the above view bared on the denaturation of myosins.
1) Bull. Jap. Soc. Sci. Fish., 18, 319-326 (1953).
2) Ibid., 17, 377-384 (1952).