VPI-G-78-004 c. 3 COO&a.mal l Ve, r.as el@>luis VcmV lan, VIRGINIA POLYTECHNIC INSTITUTE AND STATE UNIVERSITY Slacktburg, Pirtttnia 24061 EOOD SCIENCE AND TECHNOLOGY NOTES e ~so SALTING FISH p Oy@ By Sharon R. Turner The next time you come home with a Salting is usually done by one of sizable catch of fish, you might want two methods, brine salting or dry- to consider preserving them in an en- salting, In the brine salting pro- tirely different manner. You probably cess the fish are salted and layered never considered salting fish, but in a container which holds the fish the procedure is simple and is one in the brine liquor that seeps from of the oldest methods of food preser- the salted fish. In the dry salting vation. Our earliest records of food method the brine liquor that escapes preservation practices include using from the fish is allowed to drain salt for preserving fish. Salt has away. Though commercial salting of long been used both as the primary fish has declined significantly in preserving ingredient, and in combina- this country, a small quantity of tion with other methods such as dry- fish are still salted. Most of this ing and smoking. is exported to the Caribbean, South America, and southern Europe. In recent years salting, as a pre- servation technique has become less popular because of development of quick freezing preservation methods Mhy Salt Slows OownSpoilage for fish. Frozen fish have much the Common salt or sodium chloride, if same flavor as fresh fish, while present in sufficient quantities, will salted fish have a distinct flavor slow down the processes that occur in derived from the salting process. fish during spoilage. Spoilage is The Virginia CooperativeExtension Service by law andpurposeis dedicated to serveall peopleon an equaland nondiscriminatory basis, An Equal Opportunity/Affirmative Action Employer. An EducationalService of the Virginia PolytechnicInstitute and State Uniuersity, Virginia's Land-GrantUni uersity, with US, Departmentof Agricultureand Commerceand Local GovernmentsCooperating, brought about by two causes: ! sulfates!. These impurities give the autolysis, the deterioration of the fish a firmer white flesh which has bodily tissues after death by enzymes provento be moremarketable. They which are part of the biological make- also give the fish a sharp bitter up of the organism; ! deterioration taste characteristically associated due to bacteria already present in with salted fish, the fish, which grow rapidly under If these impurities are present in favorable conditions and produce en- sufficient quantities, the fish may zymeswhich break downthe fish tis- spoil becausethe absorption of salt sues, Usually the quantity of bac- is inhibited. teria in the body of a fish is small, but they are often introduced through ! The thickness of the flesh of handling, cleaning, washing, etc, Most the fish can also slow the penetra- of these enzymesand bacteria are de- tion of salt. If fish are salted stroyed or rendered inactive in a con- whole or round beheaded and envis- centrated solution of salt. cerated!, the enzymes contained in the fish's body may cause the fish As salt is being absorbed into the to spoil before salt is taken into fish, the bacteria and the enzymes the flesh in sufficient quantities are still active, and their growth to arrest spoilage. Since most of and activity continues until a certain the enzymescausing autolysis are in level of salt concentration is reached. the blood and organs of the fish, At that level, bacterial growth and whole fish are more susceptible to activity are arrested and spoilage this effect. Enviscerated fish prevented. The presence of more than should be thoroughly cleaned to min- 6". salt in solution in the tissue of imize this effect. the fish retards both autolytic and bacterial decomposition. If the up- ! Likewise, if the fish is not take of salt is slow, the fish can fresh when it is salted, the enzymes becomespoiled before this level is and bacteria may have caused the flesh reached. to deteriorate to such a degree that the rate of salt absorption is slower than the decomposition of the fish. Factors Affecting Salting Process The fat content in fish significantly Several factors affect the rate of affects the salting process. Fatty salt absorption into the fish. These fish do not as readily absorb the salt include ! the purity of the salt; and therefore bacterial growth may not ! the thickness, ! freshness and be slowed quickly enough to prevent fat content of the fish; ! the tem- spoilage. perature; and ! the care and clean- ! Spoilage can also be enhanced iness used in handling the fish. or retarded by the temperature during ! If a solution of pure sodium salting. At very high temperatures chloride is used, fish do not acquire bacterial growth may be so rapid that the bitter taste commonly associated the fish become spoiled before they with salted fish, but they become absorb enough salt. Even after fish soggy and yellow. Fish salted with are salted, they deteriorate much more pure sodiumchloride are most like rapidly at high temperatures than at fresh fish when freshened soaked cool ones. Heavily cured fish those with water before preparing!, but which were cured in a concentrated most commercially salted fish are pre- solution! may be preserved at high pared in salt containing impurities temperatures for only a few days but calcium and magnesium salts and can be held at lower temperatures much longer. ! If the fish are not handled same species. Also the statistics and stored properly under sanitary are based upon relatively small conditions the initial bacteria count samples. The following lists can in the salting process maybe quite serve as a general guide. Table I! high, Also rough handling can tear and bruise the flesh of the fish and Fish have been categorized as lean consequently shorten the amount of when the percentage of fat is less time the fish can be held before than 2.5e, moderate between 2.54 and spoiIage. 6.54, and fat if over 6.5't. Exception for species within a common name have been noted. Changes Due to Salt Absorption Salt preserves fish by extracting Table 1. Fat Content of Fishes water from the tissues and replacing it with salt. This absorption occurs until the concentration of salt in Some FAT fish are: the tissues is the same concentration Butterfish Chinook salmon as in the solution surrounding the Freshwater eels Sockeye salmon fish, or until it reaches an upper Atlantic herring Shad limit of about 20+. Oncethe quantity Pacific herring Lake trout of salt in the fish rises above 9't, Atlantic mackerel Rainbow trout irreversible changes take place in Sablefish Whitefish the muscle proteins. At this point Some MODERATELYFAT fish are: the fish is said to be "struck through." The inner flesh loses much of its trans- Albacore Mullet Blue fish Coho salmon lucent appearance and stickiness. Carp barbus! Chum salmon Carp cyrpinus! Pink salmon Indian carp Sardines Select Fish Carefully Chub Scup Conger eels Smelt Before beginning the salting process, Lake herring Swordfish it is important to consider the char- Pacific mackerel Brook trout acteristics of the fish you wish to Mackerel scombermorus! Dolly Varden Mackerel auxis! trout salt. Somefish have a higher fat Mackerel scomber! content and should probably be salted Bluefin tuna using the brine rather than the dry- Some LEAN fish are: saIting method, since the brine method Snake eels Haddock gives a more consistent distribution Fimbriated herring Hake of salt. Fatty fish do not as readily Indian mackerel Halibut absorb salt and are thus more likely Pompanoor permi Perch to spoil. Bigeye tuna Pike Yellowfin tuna Pollock Once the fish are salted, fat tissues Carp cirrhina! Porgies are susceptible to rancidity due to Cod Rockfi sh oxidation, so fatty fish need to be Croaker Snapper Flounder Soles kept in cold storage or in a manner Grouper that prevents them from oxidizing, Whiting Such handling is more successful or easier! with the brine method. Salt Purity Is Important It is difficuIt to classify fish accurately based upon fat content be- For salting, the purest salt with cause this quantity varies considerably the finest grqin available should be from one fish to another within the used. Salt which is virtually chemi- cally pure less than l% impurities! results in fish with a milder, more the brine, the fish can be scored pleasant flavor, which do not need at 1-2 inch intervals along the prolonged freshening. The finer the length. When scoring the flesh, the salt, the more rapidly the brine forms, skin should not be cut. Large fish and thus the more rapidly the flesh is can be filleted and thick-skinned; penetrated with salt. Standard curing spiny or large-scaled fish should salt is available from salt companies, be skinned before brining. butcher supply firms, and often rural The prepared fish should be washed feed stores. thoroughly in fresh water and then For home preparation the brine method soaked in a brine of 1/2 cup of salt or gaspe is becoming more popular. in one gallon of water for 30-60 minutes. This will draw any blood from the fish and cut any remaining The Heavy Cure Method skin slime. Most small or medium sized fish are After the fish are drained for 5-10 prepared for brining in the same man- minutes, they should be dredged or ner: they are scaled, beheaded, en- coated! with salt. The fish are now viscerated, and split along the back- ready to be placed in the container bone. To facilitate penetration by in layers. A good container for brining is a stoneware crock.