FISH PRESERVATION, PROCESSING, Transporting

BY: Muhammad LaiqueSubmitted To: Dr. Asma

Karim

Introduction Fish processing(primary processing) Fish preservation methods(secondary

processing) Transportation

Contents

IntroductionIn 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.

“The term fish processing refers to the processes associated with fish and fish products between the time fish are caught or harvested, and the time the final product is delivered to the customer.”The harvested fish should be cleaned and cooled as soon possible due to their strong digestive juices, fish spoil very soon and if not gutted and cleaned promptly may develop off flavor and color.A sharp knife, clean cloth, plastic bags and crushed ice must be kept ready for gutting and cleaning of fish.With the help of knife, fish should be cleaned and bled.Throat should be cut and gills and entrails are removed.Cleaned fish first be put in plastic bags and then in ice.To prevent contamination, hands, working area, cutting boards, knives and other utensils should be properly cleaned with water and soap.

Processing Of Fish

FISH PRESERVATION Preservation is the processing of food so that they

can be stored for a longer time. Preservation of fish is done to prevent spoilage. Since fish is very perishable, it is therefore, necessary to

preserve fish if not consumed or disposed immediately. Fish preservation is the method of extending the shelf

life of fish and other fishery products by applying the principles of chemistry, engineering and other branches of science in order to improve the quality of the products.

Some of the important reasons for preserving foods are1. To take care of the excess produce.2. Reaches areas where the food item is not available3. Makes transportation and storage of foods easier4. Preserving Foods at Home

Fish Foods can be preserved by the following methods-

(i) Salting (ii) Dehydration (ii) Increasing temperature(Smoking) (iii) Lowering temperature(chilling and freezing) (iv) Using preservatives(Canning and pickling)

METHODS OF FISH PRESERVATION a. 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.

There many different kinds of salt, some being better than others for fish curing.

A distinction must be made between the two chief techniques of salting: 1)wet salting2)dry salting.

Wet Salting: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 watertightcontainer, 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.

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 so that the salted brine can penetrate the flesh.

Dry SaltingDry 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.Layers of fish must be separated by layers of salt. It is a valuable method when one has no containers.

SUN DRYING AND 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 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!).

If these conditions are not fulfilled the fish must be put for one night in brine, or dry salted.

They can then be dried the next morning.

Smoking Any kind of fish can be smoked. There are three

main methods of smoking: (a) cold Smoking; (b) Hot smoking; (c) Long smoking.

Cold Smoking: Cold smoking is exactly what it sounds like. Cold-

smoked fish are not cooked, because the temperature

generally does not exceed 43° C. 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 and cod.

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.

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.

Chilling This is obtained by covering the fish with layers of

ice. However, ice alone is not effective for long

preservation . Because melting water brings about a sort of

leaching of valuable flesh contents. Which are responsible for the flavor. But ice is effective for short term preservation such

as is needed to transport landed fish to nearby markets or to canning factories etc.,

FreezingFreezing 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.

CanningCanning This is a very effective method though costly. Product is very god and retains much of

flavor. Fish is cleaned and then cut to proper

boneless pieces in filleting plants. The pieces are then brined or pickled to

improve taste. Preliminary cooking is then carried out. 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.

Pickling Pickling is an easy method of preserving fish. Pickled fish

must be stored in the refrigerator at no higher than 40° F (refrigerator temperature), and for best flavor must be used within four to six weeks.

Only a few species of fish are preserved commercially by pickling, but almost any type of fish may be pickled at home.

Refrigerate the fish during all stages of the pickling process.

Transportation of fish and fish products Development in fish preservation and transportation

has increased significantly the share of fish production that enters international trade. Fish is traded live, fresh, frozen, cured or canned. It is transported by sea, air or land. Live, fresh and frozen fish require special care in comparison with cured or canned fish.

Important ways of transporting fish are : Through air Through land Through sea(ships) Through Boats

Live fish Transportation of live fish requires oxygen for

respiration and removal of the toxic gases and by-products that accumulate, such as CO2 and ammonia. Certain fish, like catfish, can obtain oxygen through the damp surface of their gills or through the body skin. Other fish, like the climbing perch, have accessory air-breathing organs. But most finfish are transported live in water supersaturated with oxygen and kept at a temperature low enough to reduce their metabolism. Some tropical fish may not support temperatures below 10°C.

Fish is often starved (also called conditioned) before transportation to reduce its metabolism and increase the packing density. Crustaceans are transported live in wet packages using wet sawdust or other ways to keep the atmosphere surrounding the live animals humid and cool.

Quality and Quantity of Fish Oxygen pH, Carbon Dioxide and Ammonia Temperature Biochemical Changes and Stress in

Transported Fish

THE MAIN FACTORS AND PRINCIPLES ASSOCIATEDWITH FISH TRANSPORT

The quality of fish transported is a decisive criterion. The fish to be transported must be healthy and in good condition. Weakened individuals should be eliminated from the consignment, particularly when the temperature during shipment is high. When the fish are of poor quality, even a great reduction of fish density in the transport container fails to prevent fish losses. Weak fish are killed at a much higher rate than fish in good condition when the transport time is longer.

Quality of Fish

The most important single factor in transporting fish is providing an adequate level of dissolved oxygen. The ability of fish to use oxygen depends on their tolerance to stress, water temperature, pH, and concentrations of carbon dioxide and metabolic products such as ammonia.

 Heavier fish and those transported in warmer water need more oxygen. For instance, if the water temperature increases by 10°C (e.g., from 10 to 20°C), oxygen

Some conversion coefficients of oxygen demand are indicated by the FRG recommendation (1979):

OxygenOxygen

Fish type Oxygen Demand

trout 2.83

perch 1.46

pike 1.10

Eel 0.83

NOTE:  Taking the oxygen demand of carp as 1

The source of the water used during transport must have been tested before dispatching a mass consignment of fish. The water pH level is a control factor because the proportions of toxic ammonia and CO2 contents are direct functions of pH.

With increasing transport time, CO2 production through fish respiration shifts water pH towards acidity. Water pH levels about 7–8 are considered as optimum. Rapid changes in pH stress fish, but buffers can be used to stabilize the water pH during fish transport. The organic buffer trishydroxylmethylaminomethane is quite effective in fresh and salt water.

Ammonia (NH3) builds up in transport water due to protein metabolism of the fish and bacterial action on the waste. Decreasing metabolic rate of the fish by lowering the water temperature, and thus lessening fish activity, reduces the production of NH3.

pH, Carbon Dioxide and pH, Carbon Dioxide and AmmoniaAmmonia

Shipment conditions also influence the composition of fish blood and the parameters of blood serum biochemistry. Increased temperature and a lower fish weight-to-water concentration ratio mean a higher number of erythrocytes and a greater haemoglobin concentration of fish blood. No such changes occur at lower temperatures and a lower fish proportion in relation to water volume 

Biochemical Changes Biochemical Changes and Stress in and Stress in

Transported FishTransported Fish

 A fish transport tank wagon (Vollmann-Schipper, 1975) M - technical space and attendant's booth, U - pump and air compressor, T - Transport tanks 1 and 2, S - oxygen cylinders, A -tank drain, F - water aeration (for details see Fig. 50), L - loading space, W - circulating water distribution system, S + D - oxygen or compressed-air distribution system

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

CHEMICAL METHODS FOR WATER AND FISH TREATMENT DURING TRANSPORT

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References

That Was All.Thank you for your attention.Any Questions?