Fish preservation and processing by smoking / drying are methods used by artisanal fishermen to avoid spoilage of their catches Fish as a rule has very short life span once outside its natural habitat which makes finding an effective method of preservation after harvesting a very important factor in pursuing a fish farming venture.
Handling your catch of the day begins with cleaning, and icing or freezing the fish as soon as possible. The four most popular methods of fish preservation are freezing, canning, smoking and pickling.
Top quality fresh fish are essential for fish preservation. Of all flesh foods, fish is the most susceptible to tissue decomposition, development of rancidity and microbial spoilage. Safe handling of fish is important to reduce your risk of food borne illness and to produce a quality meal.
The following are some methods of preservation.
1. FREEZING METHOD OF FISH PRESERVATION
Freezing can keep products in near perfect condition for very prolonged periods. Freezing is essential for export purposes. Freezing becomes extremely effective, if it is combined with cold storage [i]. Fish that have to be preserved by freezing should be cleaned and packed for easy operation and maximum use of freezing space.
When fish is intended to be stored for a long period, quick freezing is preferred which inhibits bacterial action. During quick freezing every part of the product comes within the range of 0o to -5oC. Properly frozen fish at -20oC retains its physical properties and nutritive values for a year or more and is almost as good as fresh fish[ii]. This can be achieved using a blast freezer.
This is the simplest, most convenient and most highly recommended method of fish preservation. A good quality frozen product requires the following:
- Careful handling of the fish after catching.
- Removal of the guts and thorough cleaning of the fish soon after catching.
- Wrapping material or method that is airtight and prevents freezer burn and the development of undesirable flavors.
- A freezer storage temperature of 0 degrees F or lower.
- Remove the guts and thoroughly clean the fish soon after catching.
2. DRYING METHOD OF FISH PRESERVATION
Drying involves dehydration i.e. the removal of moisture contents of fish, so that the bacterial decomposition or enzymic autolysis does not occur. When moisture contents reduce up to 10%, the fishes are not spoiled provided they are stored in dry conditions. Fish drying is achieved either naturally by sun drying or drying it mechanically.
When you lack the specialized equipment for canning or pickling fish, drying is a quite convenient method. You should first clean and fillet the fish you plan to dry, slicing it into thin strips. Hang each fish strip out to dry in the hot sun with thread or thin wire for 12 hours. Once the fish strips develop a dry coating, bring the fish inside. As fish continues to dry, the lack of water will suspend all microbial activity. Once dried, your fish can be used to make soups, stews, or condiments. If you plan to smoke your fish, you can dry the fillets in a smokehouse at 85 to 100º F. High-temperature drying is ideal for large whole fish and destroying any present bacteria.
3. SALTING METHOD OF FISH PRESERVATION
Salting is a process of preserving fish with the use of common salt (sodium chloride), as a preservative. Which penetrates the tissues, thus checks the bacterial growth and reduce the process of spoilage. Salting commences as soon as the fish surface of the fish comes in contact with common salt and the end product shall have the required salinity with taste and odour. Some of the factors involved in salting of fish which play an important role are purity of salt, quantify of salt used and weather conditions like temperature, etc.
During the process the small fishes are directly salted without being cleaned. In the medium and large sized fish; the fish are gutted, washed and filled with salt for uniform penetration through flesh. Large fishes like sharks are cut into convenient sized pieces. Generally, salting is used for temporary preservation of fish. The salt used should be pure common salt so as to keep the quality of the fresh fish. Similarly, fish could be soaked in a solution of water and salt (brine), a process known as Brining. Brining is not used as such as a preservation method but as preparation for smoking or drying.
Procedure:
1. Wash the fish thoroughly with clean and fresh water.
2. Split the fish into butterfly fillet and remove the gills and internal organs. Wash fish again thoroughly.
3. Place the fish in a strainer and drain.
4. Prepare the brine solution (i.e., mixture of water and salt). For a 60-kg. fresh fish, use 6.5 kls. of salt and 5 gallons of water.
5. Soak the fish in brine solution for one hour.
6. Drain the salted fish.
7. Rinse the fish thoroughly under running water to wash
off excess salt.
8. Arrange or lay fish in wire screen mesh. Do not place the fish on top of each other so that fish will dry evenly.
9. Cover the fish with the other half of the screen mesh/wire screen to prevent contamination while drying.
10. Dry fish under the sun or direct sunlight for two to three days.
11. After drying, allow the dried fish to cool for at least 6
hours at room temperature.
12. Weigh, pack, seal, and store dried fish at room temperature.
4. CANNING METHOD OF FISH PRESERVATION
This preservation method is popular amongst sailors due to its ease and consistency. You should only can fresh fish that has been cleaned and gutted within two hours after catching. You can easily clean a fish by removing the head, tail, fins, and scales. Wash and remove all blood before splitting the fish lengthwise. Keep the cleaned fish on ice until you’re ready to start canning. You will need a pressure cooker, canning jars, lids, rings, a canning funnel, a stock pot, bowls, large spoons, a sharp knife, towels, and a large bowl to bring your fish in salt water. You should soak your fish in a salty brine for one hour before canning. Drain the fish for 10 minutes before storing them in the canning jars, skin-side next to the glass. Leave at least one inch of space at the top of each can. Using pint-sized canning jars, you should plan for 100 minutes of pressure canning per fresh fish or 110 minutes for smoked fish.
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References
[i] Anthonio, G.B.O., 1970. Fish marketing survey in the Kainji Lake Basin Yelwa area study. Ibadan, Nigerian Institute of Social and Economic Research, May.
[ii] Culled from: Lecture note on processing and fish preservation by NPTEL India
[III] https://extension.umn.edu/preserving-and-preparing/preserving-fish-safely#canning-fish-125711
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