Method of Fish Preservation and Transportation.pptx
- 1. TOPIC Method of Fish Preservation and Transportation 1
- 2. Introduction Fish preservation methods • Salting • Dehydration • Smoking • Chilling and freezing • Canning and pickling Transportation 2 Contents
- 3. Introduction In some places, more fish is caught at times than can be consumed. Methods are used in keeping the surplus fish in good condition for later consumption. Again, fishermen sometimes cannot return to their villages promptly with fresh fish they have caught, and it will be of value to them to know how to process(primary processing) and preserve(secondary Processing) their catch by simple means. It is also necessary to transport fish to target market or factories while it is in good quality. 3
- 4. Reason Behind Fish spoilage; Microbial action Enzymatic Reaction Chemical action 5
- 5. Fish preservation Methods Fish Foods can be preserved by the following methods. Salting Dehydration Smoking Chilling and freezing Canning and pickling 6
- 6. Salting Salt is the preservative agent used to lengthen the shelf life of fish and fishery products as it absorbs moisture from organism and drastically reduce spoilage. This is used in almost all methods of preservation except in icing, refrigeration and freezing. Two chief techniques of salting ; • Wet salting. • Dry salting. 7
- 8. 9 Wet Salting; • This is the cheaper, since it requires lesser amounts of salt. • The principle is to keep the fish for a long time in brine. • The equipment needed consists of a watertight container, which can be a tin, drum, barrel, etc • To make the brine, one takes four parts of clean water (sea or fresh water) and one part of salt. • If the salt is coarse, it has to be ground or pounded first. • It is then dissolved into the water by stirring with a piece of wood. • To be good, the brine must float a fish.
- 9. Cont… The next step depends on what kind of fish one wants to salt. It is best first to cut off the head and gut, and clean the fish, though small fish can also be salted whole. Large fish must be cut open, and it is preferable to take out the backbone. Fish with heavy armour of scales must be scaled. In places where the flesh is thick, slashes must be made 10
- 10. Dry Salting; In this method the fish is salted but the juices, slime and brine are allowed to flow away. Dry salting can be done in an old canoe, or on mats, leaves, boxes, etc. In any case, the brine formed by the fish juices and the salt must be allowed to run away. For two parts of fish, one needs one part of salt. It is a valuable method when one has no containers. 11
- 11. DEHYDRATION Drying is the process in which moisture is removed by exposure to natural air current as humidity is regulated by climatic condition. Dehydration is the process of removing moisture with the use of mechanical device that provides artificial heat for drying. Very small and thin fish(Bombay duck,prawns) can be dried straight away in the sun if they are brought in early enough in the morning (and if, of course, the sun is shining!). Cool dry air prefered 12
- 13. Smoking There are three main methods of smoking: (a)Cold Smoking (b)Hot smoking (c)Long smoking 14
- 15. Cold Smoking; Cold smoking is customarily performed below 30° C to prevent undesired changes in the muscle texture. To maintain the proper temperature, ensure uniform drying and preserve the desired colour, it is necessary to use an indirect source of heat and smoke. The cold-smoking process is primarily used for salmon. Other traditional cold smoked items include black cod (sablefish),trout, eel, herring, haddock. 16
- 16. Hot Smoking: The hot smoking system can be used for immediate consumption or to keep the fish for a maximum of 48 hours. Small fish can be salted first for half an hour . After salting they are put on iron spits and dried in a windy place or in the sun for another half hour, and then hot smoked. The fish will be ready in about one hour. An indication that they are done will be found in the golden yellow colour of the skin. Hot-smoked fish are moist and juicy when properly finished. Because of this, they have a relatively short shelf life and must be refrigerated. 17
- 17. 18 Long Smoking: If fish must be kept in good condition for a long time, for instance, two or three months or even longer, it can be done by smoking, provided the fish is not oily. For this purpose, a small closed shed made of palm leaves or other local material can be used. The dimensions of the shed depend, of course, on the quantities of fish to be smoked, but the height should in no case be less than six feet. In this shed, racks are built to hang the fish from or to lay them upon. Hanging the fish on spits is the best method, but they can also be laid on loosely-woven matting. One can start hanging fish three feet from the bottom up to the roof.
- 18. Chilling • fish covered with layers of ice. • Temp. range(0 to 8 c) • But ice is effective for short term • Chilling needed to transport landed fish to nearby markets or to canning factories etc., 19
- 19. Freezing; This is more effective than chilling. Freezing is achieved either by using a mixture of ice and salt or refrigeration. The sub zero temp so obtained keeps the fish frozen throughout. To prevent rancidity, the frozen fish is subject to glazing with water or it is wrapped in a cover of moisture proof wax paper. Glazing is dipping the frozen fish in water so that finally a layer of hard ice surrounds the fish. This layer affords protection against exposure of fish fat to atmospheric oxygen, thus preventing rancidity. 20
- 21. Canning; • Complicated,costly but effective • Product is very good and retains much of flavor. • Fish is cleaned and then cut to proper boneless pieces. The pieces are then brined or pickled(1 gallon water.1/2 cup table salt) to improve taste. • Cooked pieces are then put in cans. • Final cooking combines sterilization with steam and high temperature at 110celsius. • The cans are finally sealed in canneries. • Keeping period depends upon the quality of raw material used as well as the vacuum created in the sealed cans. 22
- 23. 24 Pickling • Ingredients of pickled Fish (fish, water, vinger, acetic acid, salts) • Pickled fish must be stored at 40° F (refrigerator temperature), • Used within four to six weeks.
- 24. Transportation of fish and fish products Important ways of transporting fish are : Through air Through land Through sea(ships) Through Boats 25
- 25. Factors associated with fish transport; Quality and Quantity of Fish Oxygen pH, Carbon Dioxide and Ammonia Temperature Biochemical Changes and Stress in Transported fish 26
- 26. 27 Fish type with their oxygen demand; Fish type Oxygen Demand trout 2.83 perch 1.46 pike 1.10 Eel 0.83
- 27. CHEMICAL METHODS FOR FISH TREATMENT DURING TRANSPORT; • Use of Fish Tranquilizers • Application of Sodium Chloride and Calcium Chloride • Chemicals as Oxygen Sources (K2S2O8, Na2S2O8, (NH4)2S2O8) • Bacteriostatic Chemicals • Buffers • Ammonia Control • Antifoam Chemicals 28