Fish processing is a way of preserving fish and at the same time improving their quality. In the process, the properties of the fish change.
Fish Processing Methods
There are many ways to process fish. Some methods such as salting and drying have been used since the ancient times, long before modern technology was introduced.
Others involved the use of chemicals and electrical devices. But whatever process is used, the fish to be processed should always be fresh.
The methods employ in fish processing include the following:
1. Fish Salting
Salting is the process that lowers the moisture or water content of fish and other fishery products to a point where microorganisms cannot live and grow. Sodium chloride, or salt, improves fish texture because it firms up the fish. Salt partially dehydrates the fish and kills the bacteria.
Three basic methods of applying salt to preserve fish:
Pickle Salting – cover the fish with salt and pack them in layers in watertight containers. This forms the pickle that serves as the saturated brine solution that covers the fish completely.
Brine Salting – immerse the fish in a saturated solution made up of 25 parts of salt and 100 parts of water. Brine salting is done only as a temporary way to preserve fish before they are dried, smoked, or processed.
Dry Salting – run granular salt on the fish. The proportion of salt to fish varies from 10% to 35% of the fish weight.
Steps in Fish Salting
Place the fish either in crushed ice or frozen brine.
Remove the fins.
Remove the head (optional).
Split the fish along the dorsal section. Spread it open.
Remove the internal organs such as the intestines.
Take out the black membrane of the fish.
Wash the fish thoroughly and drain it a little.
Rub the fish well with salt.
Arrange the fish in a container. Place the container inside a refrigerator.
2. Fish Smoking
This method combines with salting, precooking, and drying. The final process is smoking, which dehydrates the fish further. The smokes give color and flavor to the fish.
Steps in Fish Smoking
Clean the fish by removing the gills and make 1/2 inch slit in the fish belly. Wash the fish thoroughly with clean water.
Soak the fish in a brine solution (1 part of salt to 10 parts of water) for 20 or more minutes, depending on the size of the fish.
Place the fish in the immersion basket made of woven bamboo strips or wire netting. The basket will be suspended during the immersion in boiling brine. Cook for 2-4 minutes or more, depending on the size of the fish.
Drain the fish. Allow them to cool after being cooked in brine solution. Place it in a layer of wire screen (rattan or bamboo) and have it dried in a cool and shady place.
Smoke the fish in tin cans for 1 to 2 hours until it gets golden brown. The length of smoking actually differs, depending on the size of the fish and the smoke produced.
Packed the smoked fish in coarsely woven bamboo baskets. Line the sides and bottom of the baskets with old newspaper. Cool the fish completely before packing them to allow moisture to escape and prevent the attack of mold and bacteria.
Read Also : Fish Preservation and Processing Guide
3. Fish Drying
This method is also known as natural dehydration. Like the salting method, it lowers the water content of the fish to a point where microorganisms, bacteria, enzymes, and yeasts cannot grow and multiply.
The most popular fish preservation method is solar drying. It is done in combination with salting. Fish dried under the sun look and taste better.
Steps in Fish Drying
Wash the fish thoroughly.
Soak the fish in 10% brine solution for 1/2 hour to draw out the blood.
Squeeze or open the belly cavity. Remove the visceral or internal organs.
Soak the fish for 3-6 hours in a concentrated brine solution to partially draw out the moisture or water content of the fish.
Place the salted fish in drying trays and dry it under the sun.
When the fish are thoroughly dried, pack them and store them in a clean, dry place.
4. Fish Curing
This method uses chemical preservatives (including vinegar and salt), smoke, and other physical factors to reduce the moisture or water content of the fish. Cured fish or fishery products possess flavor and texture completely from those of the fresh fish.
5. Fish Dehydration
Dehydration is an artificial process of drying because it is done with the use of mechanical devices, such as an oven, that produce artificial heat for drying.
6. Fish Pickling
Pickling is a method of preserving food in brine or vinegar. It can be done with or without bacterial fermentation.
7. Fish Cooking
Cooking is the best way to prevent wastage or spoilage of fish. Cooking fish with vinegar, like in paksiw, prolonged the period of preservation.
8. Fish Canning
Canning is the packing of fish in airtight containers such as tin cans and glass jars, which prevent air and microorganisms from entering.
Through the heat processing, microbes inside the can are destroyed, thus preventing spoilage under normal condition and allowing the fish to be stored for longer periods. Sardines and salmon are the most commonly canned fish in the market.
Steps in Fish Canning
Remove the scales of the fish.
Remove the internal organs. Cut off the head and the tail of the fish.
Cut the cleaned fish to fit the size of the can to be used.
For 30 minutes, soak the fish in 20% brine solution.
Half-fry the fish in oil.
Fill each can with half-fried fish. Leave about 1/4 inch space. Add a tablespoonful of corn oil and tomato sauce. Do not add salt because the fish has been brined.
Sealed the filled cans temporarily. Use the first roll operation of the can sealer.
For 10 minutes, stem the clinched cans without pressure to exhaust the air inside the cans. Then, seal the can completely.
For 45 minutes, process the sealed cans at a 15 lb. pressure using the can sealer.
Immediately, coll the processed cans in running water.
9. Fish Fermentation
Fermentation is a fish preservation method in which fish in brine solution undergo chemical reaction. Bagoong is the most popular fermented product in the Philippines.
Steps in Fish Fermentation
Clean the fresh alamang well. Remove sticks, shells, seaweeds, and other materials.
Wash the alamang in a weak brine solution (1 part of salt to 9 parts of water). Drain it well. Cover the container while draining the alamang to keep flies away.
Mixalamang thoroughly with salt (1 part of salt to 3 parts of alamang).
Place the alamang-salt mixture in a clean container.
Store the bagoong in a clean, warm place.
In summary, fish is a very important foodstuff in developing countries, due to its high protein content and nutritional value. However, it is a greatly perishable product, especially in hot climates and tropical areas where cold preservation techniques are often missing.
Quality losses can occur very rapidly after catch. Fish salting/brining, drying or smoking, are traditional techniques for improving preservation and storage, which increase availability to consumers.
Fish that are not taken to the market fresh must be preserved in some way after harvesting. All fish have bacteria in their intestines; as soon as they die, these bacteria begin to multiply, and the process of decay begins. So the first thing which must be done – as soon as possible – is to remove the intestine.
After this is done, go on to preserve the fish in the way chosen. Fresh fish are characterized by certain properties of their colour, skin texture, eyes, gills, flesh and odour; the same way there are some changes that characterized fish spoilage (biochemical change, rigor motif in muscles, muscle tendering and spoilage).
It is imperative to understand that all processing methods are preservation method but all preservation methods are not processing methods. There are a number of way to preserve fish (-cooling and icing, salting and pickling, paste and sauces, air drying and smoking/kiln drying).
Fish Processing is a way of preserving fish and at the same time improving their quality. In the process, the properties of the fish change.
There are many ways to process fish. Some methods such as salting and drying have been used since the ancient times, long before modern technology was introduced.
Others involved the use of chemicals and electrical devices. Basically, the fish processing methods include canning, fermentation, pickling, dehydration, curing etc.
Read Also: How to Setup a Tomato Farm
