魚肉内における塩類の移動速度 ＩＩ 魚肉内および表皮を通した食塩の移動速度

Abstract

Penetration and extraction (desalting) of various salts in tuna flesh had been studied under various conditions in our previous paper. In this study, tranfer rates of NaCl have been measured for flesh of river chum (pre-spawning river chum salmon) and ocean chum (pre-spawning chum salmon caught in the North Pacific Ocean), in comparison to tuna flesh and the penetration rates into both salmon flesh through skin have also been evaluated. Observed concentration distributions and amounts of penetrated salt in flesh were explained by FICK's law of diffusion. And for both direction of diffusion, parallel to or perpendicalar to fiber, there were no differences in mechanism and in diffusivities. As flesh, especially in river chum, swelled and shrank in contact with certain concentration of salt solution, the amount of salt per unit volume of swollen flesh in equilibrium were used as surface concentration in the above calculation. And this treatment was certified experimentally in short time penetration. The rates of penetration into both flesh through skin were also expressed by diffusion in composite media and by diffusion accompanied surface resistance. The diffusivity of NaCl in the skin of river chum was larger than the other one, but its over-all resistance through skin was also larger caused by its larger thickness of skin.