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-- F i s h p r o c e s s i n g --
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| Q 1. | ||
| How is caviar prepared? |
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| Q 2. | ||
| I am interested in starting a chicken ranch and at the present time I am gathering as many facts as I can concerning this business. I have read of the qualities of fish meal as a food, but I would like to know how it is made. |
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| Q 3. | ||
| Some time ago I read about a chemical in which fishes are dipped to help preserve the quality. I have noticed that some fish (shrimpboat whiting) deteriorate rapidly under ice and their stomachs burst open. Can you give me some information about this chemical? |
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| Q 4. | ||
| What information is available on the use of antibiotics to treat fish for shipment to northern markets? |
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| Q 5. | ||
| An item in Sea Secrets (May, 1965, Vol. 9, No. 5) states that the government is developing a process for manufacturing a protein concentrate for edible purposes from fishes. Are you aware that the VioBin process has been doing this since 1947 and the product has been used in countries all over the world? |
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| Q 6. | ||
| I would appreciate any available information on a simple process for extracting fish oil from fish. |
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| Q 7. | ||
| The clams and oysters of Sarasota County waters are inedible because of pollutants. I have heard that they can be purged by keeping them in a wide-mesh metal basket in Gulf of Mexico waters. If so, how long does this process take, how deep must the water be, and can they be stacked in the basket or must they be in a single layer? |
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| Q 8. | ||
| Is it true that some fish eggs are dyed black before being sold as caviar? |
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| Q 9. | ||
| I read with interest in the September-October Sea Secrets the tips on how to recognize good-quality shrimp. Can you provide similar advice about the purchase and storage of fresh fish? |
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| Q 10. | ||
| My greatest objection to filleting a fish is the odor that remains on my hands afterward. Is there some way I can remove the odor quickly? |
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| Q 11. | ||
| Is it true that fish stomachs can be used to make cheese? |
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| Q 12. | ||
| When I was young, we used to rip and eat pieces from a slab of salted codfish hanging in the kitchen. Also, my grandmother used to make Cape Cod turkey from it. Now I want to salt codfish. How is it done? |
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| Q 13. | ||
| Can you tell me what kinds of fish are used in making the imitation crab meat available in most supermarkets? Also, what dyes, flavoring substances, and procedures are used in making this product? |
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| Q&A 1. | How is caviar prepared? |
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| There are several ways in which commercial caviar is prepared, though these are essentially similar in most respects. The most common method proceeds as follows: The roe of the sturgeon (the fish most commonly used, although salmon, whitefish, lumpfish, lake herring, carp, and cod may be utilized as well) is placed on a 4-mess sieve over a large mixing tub. The roe is then rubbed back and forth over the sieve with the palm of the hand until the individual eggs drop through, leaving the membranes and connective tissue behind. About a pound of German Lunneburg salt or a half-pound of American dairy salt is sifted over each 12 pounds of eggs and the whole mass thoroughly mixed. It then becomes liquid, due to the removal of water from the eggs, forming a heavy brine. After standing for 10 minutes or longer the eggs are poured in finer sieves to drain for an hour, then packed in kegs for consumption of shipment to the canning factory. In Russia caviar is frequently pressed into cakes for export. |
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| Q&A 2. | I am interested in starting a chicken ranch and at the present time I am gathering as many facts as I can concerning this business. I have read of the qualities of fish meal as a food, but I would like to know how it is made. Perrine, Florida |
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| Fish meal is a product of reduction processes during the extraction of by-products from fish. In 1948, 104,058 tons of fish meal were produced from menhaden alone, at a value of $11,560,914. Two processes are employed. One, called the dry-reduction process, uses waste materials from the filleting of cod, haddock and halibut heads. The mass of fish is cooked, dried and placed in a hydraulic press which removes the remaining oil and water. The cake of meal from the press is ground and then sacked for market. Where oil and meal products are desired, the wet-reduction process is used. Menhaden, pilchards and other oily fishes are used in this process, which cooks, presses and reduces the mass to a liquor containing oils and water and the wet fish meal. The wet meal is dried by one of three methods: direct heat, steam tube or vacuum. When the meal leaves the drier it is about 200 degrees Fahrenheit to 400 degrees Fahrenheit and is usually cooled before weighing it into 100-pound sacks. |
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| Q&A 3. | Some time ago I read about a chemical in which fishes are dipped to help preserve the quality. I have noticed that some fish (shrimpboat whiting) deteriorate rapidly under ice and their stomachs burst open. Can you give me some information about this chemical? Mayport, Florida |
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| The deterioration you have noticed is apparently caused by naturally occurring enzymes, rather than by bacteria. The powerful digestive enzymes contained in the stomachs of fishes will act upon the intestinal cavity after the death of the fish. This action will take place even when the fish are stored in ice. In certain cases and certain species of fish, this autolytic action may rupture the stomach. If you gut the fishes carefully and promptly after capture and ice them well in order to lower their temperature as soon as possible, they will last longer. In the New England fishery, a chlorinated sea water dip has been used with some degree of success. Other chemicals show promise, but have not yet been approved by the Food and Drug Administration. |
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| Q&A 4. | What information is available on the use of antibiotics to treat fish for shipment to northern markets? West Palm Beach, Florida |
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| The use of antibiotics in certain fresh sea foods has been recently approved by the Food and Drug Administration. The tolerances set up were of five parts per million in the raw commodity. Antibiotics are powerful bacteriostatic agents that preserve the good quality of fish and lengthen its storage life when properly used. Their application, like that of many other fine chemicals, must be made by competent personnel. Certain requirements of sanitation and good handling practices are imperative if the best results are to be expected. |
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| Q&A 5. | An item in Sea Secrets (May, 1965, Vol. 9, No. 5) states that the government is developing a process for manufacturing a protein concentrate for edible purposes from fishes. Are you aware that the VioBin process has been doing this since 1947 and the product has been used in countries all over the world? Glenview, Illinois |
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| The VioBin process is satisfactory for some purposes, but is too expensive and complex to be used universally. This is why a great deal of research is under way in many parts of the world to develop a simple and cheap way of making this product. |
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| Q&A 6. | I would appreciate any available information on a simple process for extracting fish oil from fish. Ft. Myers Beach, Florida |
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| To obtain oil from marine fish it would be advisable to begin with a fish whose flesh and viscera are fatty, such as the mullet. The simplest way to extract oil would be to grind the entire fish into approximately four volumes of acetone. This will extract the fat and leave most other components behind. It is then necessary only to evaporate the solvent (using considerable care, because it is highly inflammable) to obtain the oil. If further purification is desired, chill the oil briefly in the refrigerator. This will generally result in the crystallization of steroids, leaving a transparent, clear oily layer floating on top. |
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| Q&A 7. | The clams and oysters of Sarasota County waters are inedible because of pollutants. I have heard that they can be purged by keeping them in a wide-mesh metal basket in Gulf of Mexico waters. If so, how long does this process take, how deep must the water be, and can they be stacked in the basket or must they be in a single layer? |
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| In many parts of the world, the law requires that all bivalve molluscs (oysters, clams, mussels, and scallops) must be allowed to circulate cleansed water through their respiratory and digestive systems, before they are sold for consumption. In this way, they are able to release the bacteria and viruses that are potentially dangerous to humans. This purging, or depuration, is critical if the molluscs are to be consumed raw or will not be cooked thoroughly. The length of time required for depuration depends on the degree of pollution of the waters from which the bivalves were originally taken. In Spain, for example, mussels are placed for 48 hours in seawater that has been sterilized by chlorine and then aerated. If there is considerable residential-waste pollution released in the area of the oyster beds, it may take a number of days of depuration before they would be safe for raw consumption. It is best, however, to entirely avoid eating any bivalves takes in areas that are close to population centers or industrial developments. Since metal may corrode, the container for holding the bivalves during depuration should preferably, be constructed of fishing net material or plastic netting. Stacking the bivalves will not affect the process. Sediment-free, clear waters several miles offshore in the Gulf of Mexico would probably be best; as long as they are clear, the depth is not critical. One should also keep in mind that any disturbance, such as the vibration of a boat's motor, may cause the animals to close their shells and stop filtering, thereby bringing the depuration process to a halt. |
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| Q&A 8. | Is it true that some fish eggs are dyed black before being sold as caviar? Carson City, Nevada |
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| Yes. The eggs of certain species, including whitefishes, lumpfish, and carp are dyed black and sold as caviar. Originally, the industry used carbon black to dye the eggs. The Food and Drug Administration (FDA) banned that substance, however, after evidence that it is a cancer-causing agent was found. Vegetable dye is now used. Eggs dyed black have been known to turn green after a few weeks of storage. Food scientist David Stuiber of the University of Wisconsin reports that, because bacteria are normally present in fish eggs, it is important to add enough salt when preparing caviar to prevent fermentation-the culprit that can turn the product green. Actually, the dyed eggs are substitute caviar. The FDA has defined the product caviar as one made from sturgeon eggs only, and marketed products must be clearly marked as to the fish origin. |
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| Q&A 9. | I read with interest in the September-October Sea Secrets the tips on how to recognize good-quality shrimp. Can you provide similar advice about the purchase and storage of fresh fish? Coos Bay, Oregon |
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| The following qualities are characteristic of fresh fish: a mild (not offensively strong) odor and firm, elastic flesh that, in a whole fish, is not separating from the bones and, in filets, has a fresh-cut appearance without traces of browning or drying around the edges. A whole fish should also have shiny skin with color unfaded, bright eyes that are clear, full, and often protruding, and red gills that are free from slime. The purchaser should transport the fish home as soon as possible (leaving it in the car on a hot day hastens bacterial spoilage which can make it unsafe to eat). At home, the fish should be washed under cold running water and patted dry with absorbent paper toweling. Then, it should be wrapped in moisture-proof paper or placed in an airtight, rigid container, and immediately refrigerated at 35 degrees to 40 degrees Fahrenheit. Quality and flavor deteriorate rapidly, and fresh fish should be cooked within a day or two after purchase. To freeze fish, one should wrap it tightly in heavy-duty plastic or aluminum foil (not waxed or parchment paper). A temperature of 0 degrees Fahrenheit or lower is required to maintain quality, and some fishery specialists recommend that fish stored in a self-defrosting freezer atop a refrigerator be used within seven days. Thawing of frozen fish should take place in the original wrapper, either in the refrigerator (allow about 18 hours per pound) or under cold running water (1/2 hour per pound), and the defrosted fish should be cooked immediately. Further details on this subject are provided in Marine Brief 11, Buying Quality Seafood and Marine Brief 17, Safe Handling and Storing of Seafoods, available free of charge from Marine Advisory Programs, University of California, Davis, California 95616. |
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| Q&A 10. | My greatest objection to filleting a fish is the odor that remains on my hands afterward. Is there some way I can remove the odor quickly? Burns, Oregon |
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| In order to remove the fishy odor from your hands, wash them with soap and water, rinse, and then wash them again with full-strength white vinegar. Wait a few minutes, and then repeat the process. After a final rinse in clear water, the odor should be gone. |
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| Q&A 11. | Is it true that fish stomachs can be used to make cheese? Lawton, Oklahoma |
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| Sea Grant researchers at the University of Rhode Island have had promising results in the use of digestive enzymes from the stomachs of flounder and whiting for the manufacture of cheese. Student Vicki McCabe currently is trying to improve the extraction process and increase the yield of the enzymes. The extraction process is crucial, since any tissue left with the enzymes can cause the cheese to have a slightly fishy taste. Currently, cheesemakers rely on rennet from calf stomachs. In recent years, there has been a shortage of this natural product, and rennet has gone up in price. If enzyme extraction from fish stomachs proves its potential, then a plentiful and less expensive source of supply would be available from the fish stomachs now discarded by processors. |
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| Q&A 12. | When I was young, we used to rip and eat pieces from a slab of salted codfish hanging in the kitchen. Also, my grandmother used to make Cape Cod turkey from it. Now I want to salt codfish. How is it done? Tacoma, Washington |
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| Codfish is salted via three methods commercially: kench salting, brine salting, and pickle salting; however, only pickle salting is recommended for home use. In this method, using the purest, smallest-grained salt available, the scaled and dressed fish are coated with salt and layered in a water-tight barrel or stoneware crock. A loose cover is weighted and placed over the top layer of fish. The amount of salt used depends on the thickness of the fish, the temperature, and the degree of cure desired. A light cure is about one part salt to ten parts fish, while a hard cure may be as much as three parts salt to ten parts fish. Depending on their thickness, the fish will be completely pickled in two to ten days, after which they can be sun- or oven-dried. Details of pickle salting are given in The Encyclopedia of Fish Cookery by A. J. McClane (Holt, Rinehart, and Winston, New York, 1977). However, a person on a low-salt diet is advised to limit consumption of this product. |
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| Q&A 13. | Can you tell me what kinds of fish are used in making the imitation crab meat available in most supermarkets? Also, what dyes, flavoring substances, and procedures are used in making this product? Seligman, Arizona |
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| Imitation crab, shrimp, lobster, scallops, fish cakes, and other food products made from fish gel are all known as surimi. Surimi is made from a mild-flavored, white-fleshed fish, usually the Alaskan walleye pollock (Theragra Chalcogramma).Researchers are also investigating the use of other fish, including croaker, hake, and menhaden, for making surimi gel. Surimi is produced by repeatedly washing the mechanically separated fish flesh, up to 15 times, until it is odorless and colorless. The flesh is then strained and mixed with additives to protect it from freezer damage. Sorbitol, polyphosphates, egg whites, and starch are examples of such stabilizers. Sugar and salt are usually added. Shellfish flavor is added either as shellfish meat or extract, or by artificial flavors. Japanese crab surimi reportedly contains 50 to 60 percent Alaskan pollock and up to 20 percent crabmeat or paste. The resulting paste is extruded or molded into the shape of the desired product, such as shrimp or crab legs. The imitation crab is subtly colored with food coloring to resemble crab meat. The end product is fully cooked and frozen. The product usually has the shape, color, and texture of the product it imitates, but is less expensive. Other products that have incorporated surimi paste include fish "ham," fish sausage, and experimental baby foods. |
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Rosenstiel School of Marine & Atmospheric Science Library
University of Miami, FL USA 4600 Rickenbacker Causeway, Miami, Florida 33149 Phone: 305 421 4060 Fax: 305 421 9306 E-mail: libcirc@rsmas.miami.edu |
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