Fish cured in this way are softer and more plump than those cured by the dry-salting method.
When a fish is packed in salt the salt rapidly extracts water from the flesh and a strong brine results.
The salt dissolves in the remaining flesh juices of the fish, and rapidly diffuses throughout the fish, thoroughly permeating it. By this process, therefore, the fish is partially dried and becomes thoroughly impregnated with salt.
The gradual change in the composition of the flesh is reflected in the following analysis—
| Sample. | % Water. | % NaCl. | % Fat. |
|---|---|---|---|
| Fresh herring, ungutted | 67·33 | 0·63 | 13·78 |
| Herring lightly salted, before gutting | 66·33 | 1·27 | 12·11 |
| Herring from rousing tub, gutted and salted, ready to pack into barrel | 61·09 | 1·41 | 16·14 |
| Herring, after 7 days salted in barrel | 52·67 | 7·43 | 17·10 |
| Herring, after 8 days salted in barrel | 46·90 | 11·49 | 22·50 |
The efficiency of the cure and the appearance of the finished product will be influenced by the following factors—
(a) The temperature—whether summer or winter;
(b) The freshness of the fish;
(c) The quality of the salt—its purity and grain;
(d) The quantity of salt used;
(e) The duration of the process.
(a) The Temperature. As soon as a fish is dead, it commences to decay.
In hot weather, decay proceeds more rapidly and the interior portion of the meat may become soured before the salt reaches it. Clearly, if the rate at which the salt penetrates the fish is retarded by the salt being impure, or of too fine a grain, or by the brine being too weak, the probability of the fish being spoilt is very much increased.