SALTING FISH
By Sharon R. Turner
The next time you come home with a sizable catch of fish, you might want to consider preserving them in an entirely different manner. You probably never considered salting fish, but the procedure is simple and is one of the oldest methods of food preservation. Our earliest records of food preservation practices include using salt for preserving fish. Salt has long been used both as the primary preserving ingredient, and in combination with other methods such as drying and smoking.
In recent years salting, as a preservation technique has become less popular because of the development of quick freezing preservation methods for fish. Frozen fish have much the same flavor as fresh fish, while salted fish have a distinct flavor derived from the salting process.
Salting is usually done by one of the two methods, brine salting or dry salting. In the brine salting process the fish are salted and layered in a container that holds the fish in the brine liquor that seeps from the salted fish. In the dry salting method the brine liquor that escapes from the fish is allowed to drain away. Though commercial salting of fish has declined significantly in this country, a small quantity of fish is still salted. Most of this is exported to the Caribbean, South America, and southern Europe.
Why Salt Slows Down Spoilage
Common salt or sodium chloride, if present in sufficient quantities, will slow down the processes that occur in fish during spoilage. Spoilage is brought about by two causes:
- Autolysis, the deterioration of the bodily tissues after death by enzymes which are part of the biological makeup of the organism;
- Deterioration due to bacteria already present in the fish, which grow rapidly under favorable conditions and produce enzymes which break down the fish tissues. Usually the quantity of bacteria in the body of a fish is small but they are often introduced through handling, cleaning, washing, etc.
Most of these enzymes and bacteria are destroyed or rendered inactive in a concentrated solution of salt.
As salt is being absorbed into the fish, the bacteria and the enzymes are still active, and their growth and activity continues until a certain level of salt concentration is reached. At that level, bacterial growth and activity are arrested and spoilage prevented. The presence of more than 6% salt in solution in the tissue of the fish retards both autolytic and bacterial decomposition. If the uptake of salt is slow, the fish can become spoiled before this level is reached.
Factors Affecting Salting Process
Several factors affect the rate of salt absorption into the fish. These include:
- The purity of the salt;
- The thickness,
- Freshness and fat content of the fish;
- The temperature; and
- The care and cleanliness used in handling the fish.
1) If a solution of pure sodium chloride is used, fish do not acquire the bitter taste commonly associated with salted fish, but they become soggy and yellow. Fish salted with pure sodium chloride are most like fresh fish when freshened (soaked with water before preparing), but most commercially salted fish are prepared in salt containing impurities (calcium and magnesium salts and sulfates). These impurities give the fish a firmer white flesh that has proven to be more marketable. They also give the fish a sharp bitter taste characteristically associated with salted fish.
If these impurities are present in sufficient quantities, the fish may spoil because the absorption of salt is inhibited.
2) The thickness of the flesh of the fish can also slow the penetration of salt. If fish are salted whole or round (beheaded and eviscerated), the enzymes contained in the fish's body may cause the fish to spoil before salt is taken into the flesh in sufficient quantities to arrest spoilage. Since most of the enzymes causing autolysis are in the blood and organs of the fish, whole fish are more susceptible to this effect. Eviscerated fish should be thoroughly cleaned to minimize this effect.
3) Likewise, if the fish is not fresh when it is salted, the enzymes and bacteria may have caused the flesh to deteriorate to such a degree that the rate of salt absorption is slower than the decomposition of the fish.
The fat content in fish significantly affects the salting process. Fatty fish do not as readily absorb the salt and therefore bacterial growth may not be slowed quickly enough to prevent spoilage.
4) Spoilage can also be enhanced or retarded by the temperature during salting. At very high temperatures bacterial growth may be so rapid that the fish become spoiled before they absorb enough salt. Even after fish are salted, they deteriorate much more rapidly at high temperatures than at cool ones. Heavily cured fish (those which were cured in a concentrated solution) may be preserved at high temperatures for only a few days but can be held at lower temperatures much longer.
5) If the fish are not handled and stored properly under sanitary conditions the initial bacteria count in the salting process may be quite high. Also rough handling can tear and bruise the flesh of the fish and consequently shorten the amount of time the fish can be held before spoilage.
Changes Due to Salt Absorption
Salt preserves fish by extracting water from the tissues and replacing it with salt. This absorption occurs until the concentration of salt in the tissues is the same concentration as in the solution surrounding the fish, or until it reaches an upper limit of about 20%. Once the quantity of salt in the fish rises above 9%, irreversible changes take place in the muscle proteins. At this point the fish is said to be "struck through." The inner flesh loses much of its translucent appearance and stickiness.
Select Fish Carefully
Before beginning the salting process, it is important to consider the characteristics of the fish you wish to salt. Some fish have a higher fat content and should probably be salted using the brine rather than the dry salting method, since the brine method gives a more consistent distribution of salt. Fatty fish do not as readily absorb salt and are thus more likely to spoil.
Once the fish are salted, fat tissues are susceptible to rancidity dur to oxidation, so fatty fish need to be kept in cold storage or in a manner that prevents them from oxidizing. Such handling is more successful (or easier) with the brine method.
It is difficult to classify fish accurately based upon fat content because this quantity varies considerably from one fish to another within that same species. Also statistics are based upon relatively small samples. The following lists can serve as a general guide. (Table 1)
Fish have been categorized as lean when the percentage of fat is less than 2.5%, moderate between 2.5% and 6.5%, and fat if over 6.5%. Exceptions for species within a common name have been noted.
Table 1. Fat Content of Fishes
Some FAT fish are:
| Butterfish | Chinook salmon |
| Freshwater eels | Sockeye salmon |
| Atlantic herring | Shad |
| Pacific herring | Lake trout |
| Atlantic mackerel | Rainbow trout |
| Sablefish | Whitefish |
Some MODERATELY FAT fish are:
| Albacore | Mullet |
| Bluefish | Coho salmon |
| Carp (barbus) | Chum salmon |
| Carp (cyrpinus) | Pink salmon |
| Indian carp | Sardines |
| Chub | Scup |
| Conger eels | Smelt |
| Lake herring | Swordfish |
| Pacific mackerel | Brook trout |
| Mackerel (scombermorus) | Dolly Varden trout |
| Mackerel (auxis) | Bluefin tuna |
| Mackerel (scomber) |
Some LEAN fish are:
| Snake eels | Haddock |
| Fimbriated herring | Hake |
| Indian mackerel | Halibut |
| Pompano or Permi | Perch |
| Bigeye tuna | Pike |
| Yellowfin tuna | Pollock |
| Carp (cirrhina) | Porgies |
| Cod | Rockfish |
| Croaker | Snapper |
| Flounder | Soles |
| Grouper | Whiting |
Salt Purity Is Important
For salting, the purest salt with the finest grain available should be used. Salt which is virtually chemically pure (less than 1% impurities) results in fish with a milder, more pleasant flavor, which do not need prolonged freshening. The finer the salt, the more rapidly the brine forms, and thus the more rapidly the flesh is penetrated with salt. Standard curing salt is available from salt companies, butcher supply firms, and often rural feed stores.
For home preparation the brine method or gaspe is becoming more popular.
The Heavy Cure Method
Most small or medium sized fish are prepared for brining in the same manner: they are scaled, beheaded, eviscerated, and split along the backbone. To facilitate penetration by the brine, the fish can be scored at 1-2 inch intervals along the length. When scoring the flesh, the skin should not be cut. Large fish can be filleted and thick-skinned; spiny or large-scaled fish should be skinned before brining.
The prepared fish should be washed thoroughly in fresh water and then soaked in a brine of 1/2 cup of salt in one gallon of water for 30 - 60 minutes. This will draw any blood from the fish and cut any remaining skin slime.
After the fish are drained for 5-10 minutes, they should be dredged (or coated) with salt. The fish are now ready to be placed in the container in layers.
A good container for brining is a stoneware crock. Put a layer of salt in the bottom, skin side down (or backs down) if whole. Add a thin layer of salt and another layer of fish at right angles to the preceding layer. Do not let the fish in a single layer overlap any more than is necessary. Stagger the layers so that the fish are distributed as evenly as possible. Place the top layer of fish skin side up (or backs up) and add a generous amount of salt.
The amount of salt used for the entire salting should be between a quarter to a third the weight of the fish. This amount is dependent upon the purity of the salt, the size of the grain, the temperature (warm weather requires more salt), and the size and fat content of the fish.
Put a loose wooden cover on the top layer and a weight on top of that to compress the fish and force out the brine.
Small fish will generally be completely brined in about 48 hours, while larger fatter fish may take 10-14 days.
When brining is completed, scrub the fish in a fresh full-0brine solution (one quart of salt for each gallon of water) with a stiff brush. Then repack in the crock, with a light sprinkling of salt between layers. Make sure the layers are well pressed.
Fill the crock with a fresh full brine solution and store in a cool dark place. The fish will keep like this for about 9 months, if the brine is closely watched. At any sign of fermentation the fish should be washed and repacked.
Light Cure
The procedure for a light cure is the same, but it can be used only for fresh (less than 48 hours old) lean fish and only in cold temperatures. The amount of salt used for alight cure or gaspe is in the proportion of 1 to 10. This may vary, as in a heavy cure, depending on the temperature, the type of fish, and the salt should be removed and put in a container and stored in the refrigerator. They can be kept chilled like this for a short period of time or they may be dried and chilled.
Light-cured fish are yellow when removed from the brine; when dried, they have amber-colored translucent flesh and taste somewhat like cheese. Light-cured fish cannot be kept nearly as long as heavily cured ones.
Curing Herring
Herring are handled differently. They should be brined immediately after being caught (not held on ice). They can be brined whole, gibbed, or thoroughly cleaned.
Traditionally they were gibbed. In this process the herring is held with its back to the palm, the head between the thumb and forefinger, leaving the throat clear. A short bladed knife is inserted under the gill cover. With the edge of the blade toward the stomach, a sharp twist upward and outward removes the throat, pectoral fins, gills and main gut in one operation. The strong taste associated with whole or gibbed fish has become less popular, so it is preferable to thoroughly clean the fish removing all the viscera and the head.
Thoroughly scrub the herring in a brine solution to remove scales and leach out the blood. Then drain. Layer the herring in the crock with their backs down, except the top layer that should be backs up. The brine solution of the herring should be replaced every two months.
Dry Salting
The dry-salting process requires more care and effort than the brine method. And through fish (particularly fat fish) are more likely to spoil during the dry-salting process, once the fish are "struck through" drying decreases the likelihood of spoilage. This is the traditional method for curing cod in the New England are and North Atlantic. Dry-salted cod, cusk, haddock, and mackerel can be bought in many parts of the country in wooden boxes or tubs.
Fish to be dry-salted should be bled immediately when caught. Cut the throat and remove the gills, and ice the fish; when ready to salt, clean the fish and cut it along the backbone so the flesh likes flat. Clean the fish thoroughly, inside and out, removing all traces of black skin, blood, etc. Wash in a brine of one cup of salt for each gallon of water. Scrub the fish to be sure it's clean and then drain well. Remove as much moisture as possible.
Using the finest salt available, dredge the fish in salt. Put a layer of salt in the bottom of the container to be used. The container should drain well, allowing the brine to flow away from the fish and not remain trapped in the bottom. The fish should be placed skin side down and salt spread between each layer of fish. The top layer should be placed skin side up and then thoroughly salted. The usual proportion of salt to fish is 25-33% of the weight of the fish. More of less may be needed depending upon the temperature, the salt used and the condition of the fish. A top with a weight on it can facilitate the flow of brine from the fish.
Usually the fish should be left for about 48 hours to a week, depending upon the humidity and the temperature. Under warm and dry conditions, the time could be shorter.
Once the fish are "struck through" they should be removed from the salt and scrubbed well with a brine solution so that no salt remains on the surface. Drain the fish well. They are now ready to be dried.
Drying should be done in the shade (sunlight will discolor the fish) in an area with free-flowing air circulation. A hardware sloth screen raised on legs a few feet off the ground can be used. The fish should be placed skin side down on the screen. Prop cheesecloth over the fish so flied do not spoil them. They should be turned several times the first day.
The screens must be brought indoors at night for the moisture could allow mold to grow on the fish. If the weather turns bad and the fish can't be taken outside, the fish should be salted lightly. This salt should be brushed off when they are again put out of doors.
Rapid drying produces a superior product with a clear colored flesh. The best way to tell when the fish have dried sufficiently is to pinch the thick section of the flesh. If your fingers don't leave an impression, the fish are ready for packing.
Dry salted fish are usually wrapped in wax paper and packed in wooden boxes or tubs. At home if these are unavailable you can wrap the fish and place them in the freezer. Even in wooden containers with airtight lids they should be kept in a cool, dry place.
For the majority of recipes (and tastes) dry salted fish should be freshened (soaked in fresh water from one half hour to twelve hours before preparing). Salted fish that have been freshened can be used in nearly any standard recipe calling for fish or fillets.
Other Publications
Other nutrition-related FST Notes that may be obtained (free) from the Department of Food Science and Technology, VPI & SU, or from local Extension offices:
Smoking Fish at Home - A Step By Step Guide, by Cherrie L. Kassem
History of Colonial Foods in Virginia, by William R. Hess, Jr.
Food Additives, by Dr. Anthony Lopez
Making Cottage Cheese In The Home, by Paul M. Large.
Squid - An Underutilized Species, by Chieko Hebard and Sharon R. Turner.
