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GUIDE TO SMALL SCALE PROCESSING METHODS Authors: GYÖRGY HOITSY, ANDRÁS WOYNAROVICH, THOMAS MOTH-POULSEN and ROSEANNA AVENTO GUIDE TO SMALL SCALE TROUT PROCESSING METHODS

Authors: GYÖRGY HOITSY, ANDRÁS WOYNAROVICH, THOMAS MOTH-POULSEN and ROSEANNA AVENTO

Budapest, 2012 2

Photos and illustrations by courtesy of GYÖRGY HOITSY

The designations employed and the presentation of material in this information product do not imply the expression of any opin- ion whatsoever on the part of the Food and Agriculture Organi- zation of the United Nations (FAO) concerning the legal or development status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. The mention of specific companies or products of manufacturers, whether or not these have been patented, does not imply that these have been endorsed or recommended by FAO in preference to others of a similar nature that are not men- tioned. The views expressed in this information product are those of the author(s) and do not necessarily reflect the views of FAO. 3

PREFACE This book intends to provide advice on trout preservation methods, lists the steps of processing and also describes different packaging technologies that could be utilized by small scale processing companies as well. As small scale trout farming rep- resents a notable part of , information about pro- cessing provides a mean to improve the level of services and so to increase the income of producers.

ACKNOWLEDGEMENT Authors wish to express their gratitude to Ms. ZSUZSA POLYÁK for translation and Ms. ÉVA KOVÁCS, Junior Aquaculture Officer (FAO-REU) for participation in the elaboration of this document. We would like to thank to Mr. JANNE TURUNEN, Coldfin (Finland) offering his photos to illustrate this publication out of which we used those, presented in Figure 4. Thanks are also due to Mr. ISTVÁN FÁBIÁN (www.ajel.hu and [email protected]) for the typographical design and work of this publication. 4 SMALL SCALE TROUT PROCESSING METHODS

TABLE OF CONTENTS Preface 3 Acknowledgement 3 1 Introduction 5 2 methods 5 3 Preparing fish for processing 6 4 Steps of 8 4.1 Stunning 8 4.2 Gutting 8 4.3 Cleaning 8 4.4 Sorting and grading 8 4.5 Slicing to 9 4.6 Fish preservation 9 4.6.1 9 4.6.2 11 4.6.3 Deep 12 4.6.4 Drying or desiccation 12 4.6.5 Marinating 13 4.6.6 processing 14 5 Packaging 14 6 Production offal 15 6.1 Offal quantity and treatment 16 6.2 Offal processing into fish silage 16 References 16 Glossary 17

Tables Table 1: Contents of fish 5 Table 2: Quality aspects of live fish to be processed 7 Table 3: Treatment of fish offal with sulphuric acid 16

Boxes Box 1: Preventing microbiological damage 6 Box 2: Wood used for smoking trout 12

Figures Figure 1: Flow chart of steps of fresh and production 8 Figure 2: A simple but highly sufficient place to clean fish 9 Figure 3: Steps of cutting filet of trout 10 Figure 4: Cutting the ribs out of a large trout 10 Figure 5: Small scale cold smoking apparatus 11 Figure 6: Cold smoked trout 11 Figure 7: Trout smoked on wood 12 Figure 8: Air conditioner, refrigerator and hygienic means of transport ing fish 13 Figure 9: High tech small scale packing machine 14 Figure 10: Personal hygiene of workers 17

Annexes Annex 1: Criterions of a modern fish processing plant 17 Annex 2: Product sheets of fresh and smoked trout 19 Annex 3: List of recommended further readings of related literature published by FAO 20 Introduction / Fish preservation methods 5

 1 INTRODUCTION Fish species Water (%) Protein (%) Fat (%)

Carp 78.9 16.0 4.0 Global fish production has continued to in- crease in the past 10 years. Processed Trout 76.3 19.5 0.8 and represent a large share 80.5 17.5 0.8 within this growth. These facts also under- line the importance and progress of the Pikeperch 78.9 19.0 0.8 processing industry. No matter what culture or continent, traces back to many thousand indispensable for humans. Carbohydrate Table 1: years of tradition. Warm, sunny regions content of freshwater fish is negligible. Contents of fish have been the cradle of sun-drying and cur- The protein content of fish meat varies meat ing, while improved fire-drying methods de- widely, depending on the species and, veloped to smoking. In ancient times salting within that, on the feeding, more precisely was used as an attempt to preserve meat. the type of natural fish food* or the feed of vegetables and fish has origi- consumed. nated in the Orient, whereas freezing stems The mineral compound content of fish from the Eskimos as a natural result of their meet slightly exceeds that of warm- geographical environment. blooded animals. From among fat-soluble Housewives and current lifestyle show vitamins A and D occur in fish in relatively a continuous demand for easy-to-cook large quantities. From among water-solu- , the easier the better. This is ble vitamins B1 and B2 are the most sig- in harmony with the requirements of nificant ones. Fish is also an excellent longer , easy transportability of source of omega-3 and omega-6 fatty fish products and global driving forces for acids that are essential for human health. value addition of fish food, including the As a consequence of the high water maintenance of product quality. and protein contents fish meat is easily To satisfy the interest for specific de- perishable. Spoilage causes loss of quality tails a glossary has been compiled. Fur- and value and is primarily induced by mi- thermore, tables and annexes have been croorganisms, enzymes and, after some attached. For the sake of easier identifica- time, the oxidation of fish fat. In the course tion and finding additional information, ital- of processing efforts are taken to counter- ics and asterisk symbols (*) are used at act these factors to ensure a longer shelf words clarified in the glossary. life for fish meat. In short, preservation is In order to supply the reader with more the practice of preventing spoilage while information the book also contains a list of retaining physical and chemical character- those FAO publications which deal with istics of raw material along with its biolog- fish processing. ical value and taste. Several methods are applied to curb the spread of microbes. These are cool- ing, freezing, drying, smoking, heat treat-  ment, salting and applying antimicrobial 2 FISH agents and antioxidants (see Box 1).The PRESERVATION best way of preserving freshness of a fish, is to keep it alive (Welcomme, 2001) METHODS Fish are covered with micro-organisms that can cause spoilage if mishandled or processed improperly afterwards. Fish meat has a high nutritive value. In ad- Therefore, it is essential to ensure a hy- dition to protein, fat and carbohydrates, it is gienic handling of fresh or processed fish also rich in minerals and vitamins. The com- products in each and every phase of pro- position of fish proteins is more valuable duction, storage and transportation. Quali- than that of mammals because it includes a ties which make fish suitable for pro cessing favourable portion of essential amino acids (or not) are specified in Table 2. 6 SMALL SCALE TROUT PROCESSING METHODS

 Preventing microbiological 3 PREPARING FISH damage FOR PROCESSING

Cooling When processing fish it is important to re- Cooling takes place at a temperature between 0 and 8 oC member the following principles: which slows down the process of spoilage but does not pre-  maintain the cold-chain, vent it. The method is primarily suitable only for short-term  maintain hygiene, storage.  avoid damaging or crushing fish, Freezing  work rapidly. The purpose of freezing is to prevent or reduce to the min- imum processes which spoil the quality of fish meat. Usually the first step of preparing fish for Drying processing is fishing. Fishing methods The oldest of physical fish preservation methods which is have an effect on quality. It is advisable to intended to extract water from fish in the shortest possible keep nets and lines in water for as short a time to avoid bacterial proliferation. time as possible. In addition, seining and Smoking times should be made as short An ancient mode of fish preservation. Components of as possible. It is recommended that fish smoke exercise a germicidal impact on fish meat. are handled gently and care taken to pick Heat treatment fish by holding the head in order to avoid Heat treatment is aimed to inhibit processes which lead to bruising and gaping of the flesh. fish decay by preventing enzyme activity and destroying mi- When harvesting it is important to avoid croorganisms. causing damage to fish because damaged Salting or injured skin reduces marketability of the The method is based on the preserving effect of table product. In addition, it paves a path for which is hygroscopic* hence it absorbs water from microbes micro-organism transfer from skin to flesh, and the environment. which may accelerate spoilage. Applying antimicrobial agents In case of fishing fish can be stored in Antimicrobial agents (preservatives) retain food quality and clean containers on board the fishing ves- ensure longer shelf life by protecting fish from spoilage sel. It is also important to maintain hy- caused by . Adding such agents in proper giene on board and provide a clean dosage to fish lengthens their shelf life. fishing environment. Applying antioxidants It is important to ensure optimum con- This method is applied to prevent chemical spoilage. It ditions and cause the least possible stress means the inhibition of tissue enzyme activity by adding to live fish during transportation. Observ- spoilage preventives and/or destroyers to ing and adhering to animal welfare regu- the raw material. Such organic or inorganic antimicrobial lations and avoiding bruising of fish in agents are preservatives which inhibit by mod- transit is a precondition for maintaining the ifying enzyme proteins. In terms of cellular impact location quality of fish meat. preservatives may target the cell wall, the cell membrane If there are no live fish transport facili- and the cytoplasm. Even small dosages are sufficient. Nev- ties caught and stunned fish should be ertheless, preservatives may exercise an unwelcome im- chilled to 0-5 oC. Fish should be placed be- pact on the quality (taste, color, substance, valuable nutritive tween 3-5 cm thick layers of chips. In- compounds) of preserved material. sulated boxes help to maintain the Additionally, chemical substances inhibiting or destroy- cold-chain by preventing ice from melting ing microbial cells may influence human body as well. It is too quickly. The rule of thumb is to use 1 kg a professional conviction that being cytotoxins by nature and of ice for each kg of fish. One should avoid accumulating in the body which is followed by a slow leech- making too many layers of iced fish in ing out, such agents may have a detrimental effect on boxes as the fish placed on lower-levels are human body which is also made up of cells. subject to pressure from higher-level lay- ers, which may then result in bruised flesh. If there is a choice in ice, the best is small Box 1 crushed ice, while the worst is crudely crushed block ice (Welcomme, 2001). A fish processing plant should construct Preparing fish for processing 7 and use a storage pond or tank. Fish should within about 20-24 hours. If water tempera- be starved for two days here in order to ture is lower the starvation period should be empty their guts. It will reduce chances of longer than 2 days. Considering storage fa- product contamination. In trout stored in 12 cilities harvested quantities should not ex- oC water food will pass through the gut ceed daily processing capacities.

Table 2: Healthy or fresh fish Spoiled fish Quality aspects of live fish to be Movement Vivid Slow, not reacting, scratching processed

Location Within the water On the surface, at the edges or on the bottom of water

Colour Genus-specific Dark, black

Eyes Genus-specific, healthy Opaque and abnormally looking, bright with clear lens bulging or sunken and cornea

Integument Intact, healthy Damaged, blistery, covered with parasites

Skin Bright, shiny, genus-specific Faded, dull with whitish slime colour, difficult to remove

Gills Bright red White or grey, offensive smell

Odour Genus-specific, pleasant Unpleasant, offensive smell fishy odour, characteristic to the species

Muscles Firm, elastic, vigorous Soft, stiff adherence to bones, does not spring back when pressed upon

Scales Firmly attached Easy to pick

Mucus Genus-specific, transparent Abundant in quantity, opaque

Belly volume Normal, fish submerges Strongly swollen, fish does when placed into water not submerge when placed into water

Fish Genus-specific, pleasant Offensive smell, ribs often fishy odour characteristic to pierce the meat the species

Fins Intact Damaged, broken, ruptured 8 SMALL SCALE TROUT PROCESSING METHODS

4  STEPS OF 4.2  GUTTING

FISH PROCESSING Washing of stunned fish should precede gutting. Following stunning fish are bled Steps of processing are as summarised and then cutting and gutting shall begin below. immediately. This should take place on a corrosion-resistant table fitted with a pipe for sacking fish viscera into a collecting Reception of the live fish tank. Care should be taken not to hurt the intestinal canal during gutting otherwise it may soil the fish meat. The table should Stunning and bleeding also feature a fish washer to remove blood from inside and outside the fish. Gutting The drainage of the fish washing sink should be equipped with a fat trap. Gutting is followed by the removal of Washing of cleaned fish scales, fins, head and tail depending on the species of fish and the final objective of processing. Sorting and grading Scaling can be done by rubbing a rough surface on the fish or using auto- Curing mated or hand-held scales. Heading can be done in two ways: a straight cut per- pendicular to the backbone or using a v- Smoking cut behind the gills. Heading can be done manually or using heading machines.

Warm/hot smoking 4.3  CLEANING

Cooling Cold smoking It is important to clean fish as it carries micro-organisms on its skin, which easily causes spoilage at later stages during in a controlled atmosphere processing. It is essential to use clean, running water and avoid re-using water several times. Pre-cooling, cold storage

Placing in box 4.4  SORTING AND GRADING

Delivery Sorting is the practice of separating fish into groups with different physical prop- erties while grading is the practice of sep- arating fish by quality according to Figure 1: 4.1  STUNNING certain pre-determined criteria. Contain- Flow chart of steps ers such as tumblers are needed in this of fresh and smoked The fresh bath of captured fish should be phase of the processing chain. In addi- fish production transferred to the preparatory room tion, sizing devices and scales may also where fish are stunned in a container be essential. equipped for this purpose. The process of stunning is completed with a battery operated equipment at 12–24 Volts and 0.2–2 Amperes. Steps of fish processing 9

Figure 2: A simple but highly sufficient place to clean fish (above left). Knife to cut the belly and vacuum gutting device fixed together near to the wheel brush to clean the fish from inside (above right and left below)

4.5  SLICING TO STEAKS bacterial , it is sufficient to apply table salt in a quantity of 15 percent Depending on species, fish size and the of product weight. The entire fish surface degree of processing, fish are cut, sliced shall be covered with salt which then per- to steaks, filleted and deboned. These meates into meat tissue. Uncoloured salt, steps may be performed manually or with free of additives should be applied both in machines. When filleting by hand, meat is case of dry or wet salting or their combi- carefully detached from big fish bones nation. Salting should be done in cool with a sharp knife, starting at the back. temperatures to reduce the possibilities of With proper routine, 60–65 percent of live bacterial growth. fish can be gained. Filleting machines can Dry salting is used in case of fish with also be used, though machines are species 6 percent or less fat content. Smaller fish and sizespecific. are able to take up more salt than bigger ones. In this process, salt is either rubbed into fish or sprinkled onto its surface. Wet salting means that fish are soaked 4.6  FISH PRESERVATION in ready-made concentrated * for a period of time. Salting equipment features various kegs, tubs and containers. Kegs 4.6.1  Salting are suitable for smaller fish. Fresh fish rolled in dry table salt is layered in the keg, The method is based on the preserving left to stand there for a while. Then the keg effect of table salt (NaCl) which is hygro- is capped with an airtight sealing and after scopic i.e. it absorbs water from the mi- curing for a period of time supplied to the crobes and the environment. To prevent consumer. 10 SMALL SCALE TROUT PROCESSING METHODS

When tubs are used, their bottom is had. The lower the salt concentration of covered with a 1-2 cm layer of salt, the the fish meat, and the longer the storage fish are placed on it and each fish layer is time, the lower the temperature should be. covered with salt again. This can take Minimum storage temperature of light place in a warm, cooled or chilled envi- shall be -5 oC, medium salted ronment. ones should be -1 oC and even heavily Salted fish should be stored at the salted ones cannot be stored at tempera- same temperature as the salting process tures exceeding +5 oC.

Figure 3: Steps of cutting filet of trout

Figure 4: Cutting the ribs out of a large trout Steps of fish processing 11

4.6.2  Smoking

Smoking techniques can vary widely from one region to another and are highly de- pendent on taste preferences. It is one of the oldest processing methods of fish and is highly suitable for producing products with a long shelf-life especially as it makes fish dry out. In addition, smoke compo- nents (phenols, acids, formaldehydes, creosotes) have antigermic and antioxida- tive impacts on the product. Climatic conditions have a major im- pact on smoking. The process is different in cool, moist or hilly regions from that in drier lowlands. Depending on smoking temperature there are cold, warm and hot smoking techniques. Fish should be cured in brine prior to smoking, either in strong brine or in a tra- ditionally milder one. The first is a 25–30 Figure 5: Small scale cold smoking apparatus percent brine and the latter is a 10–12 per- cent salt solution. Fish should be cured in it for about 12–16 hours and carefully turned two or three times during this period. Cleaned, washed fish should be trans- ferred in a covered plastic or corrosion- proof dish to the curing room. When water has dripped off them, fish are placed into plastic kegs or corrosion-proof, acid-resis- tant tubs and brine is poured on them. Fish is cured in the brine for a while and carefully turned two to three times. Then they are removed from the brine, hooked one by one and hanged on a rod which is placed on a rolling stand. After dripping fish are pre-dried before the stand is rolled into a smoking cabinet or room.

Cold smoking Figure 6: o Cold smoking is done below 30 C. Cold Cold smoked trout smoking takes place at a temperature of 12–24 oC. Relative shall remain These products have a shelf life of about in the range of 75–85 percent. Removed 20–50 days when stored at 0–5 oC. from the brine, fish should be drip dried before placing them into the smoking fa- Hot smoking cility. Smoking time is about 12–24 hours, Hot smoking needs even less time. How- depending on fish size. ever, shelf life of the product is reduced accordingly. Smoking is performed at a Warm smoking temperature between 90 and 120 oC from Warm smoking is at temperatures be- ½ to 2 hours. tween 30 and 80 oC but it is typically done In addition to wood smoke, liquid smoke at temperatures between 30 and 60 oC. can also be used. In liquid smoking, fish is Depending on fish size and smoke quality, dipped into a concentrate of a liquid that fish should remain 2–6 hours in the smoke. has been used to absorb smoke (Wheaton 12 SMALL SCALE TROUT PROCESSING METHODS

4.6.3  Deep freezing

Deep freezing is an up-to-date method of preservation by heat-extraction when the raw material is cooled in a fairly short time (3 to 5 hours) to a very low temperature (- 35, -45 ºC). As a result of rapid refrigera- tion free water content of raw materials is frozen to tiny ice crystals which are smaller than the cell wall, therefore, though they strain the cell wall they do not split it. The process strongly limits microorganic activ- ity while raw materials remain able to re- tain their biological value and taste. However, it requires the storage and trans- portation of deep frozen products at a con- stant, low temperature of -18 to -20 ºC. Temperature fluctuation would explicitly lead to recrystallization, the growth of tiny ice crystals. Around -18 to -20 ºC the ac- tivity of microorganisms causing spoilage slows down, some of them are even de- Figure 7: and Lawson, 1985). The liquid concentrate stroyed though the germicidal effect is still Trout smoked transfers the aroma and flavor of smoke not complete. At temperatures higher than on wood onto the product. In some developing coun- -12 ºC microorganisms may restart prolif- tries grass, coconut husks, saw dust and eration while at 10-40 ºC it reaches a pace even cow dung have been used to gener- which turns food to a health hazard. This ate smoke. is the reason behind the discouragement of refrigerating thawed but unused raw ma- Storage of smoked fish terials. Warm and hot smoked fish should be cooled before packaging and relocating to storage. 4.6.4  Drying or desiccation Daily produced and packed smoked fish should be transferred in a closed con- Drying or desiccation is aimed for at re- tainer to storage facilities where they moving water present in the food in various should be kept in separate fridges on forms of bonds. While earlier fish were melting ice temperature until delivery. dried with the heat of the sun, today’s des- Fresh and smoked fish should be stored iccating equipments are capable of ab- in separate fridges. solute drying, as well. The process re quires careful attention to lead to the least possi- Box 2 ble loss of nutrients. Wood used for Quality of dried products varies with smoking trout temperature and length of drying. Optimum temperature ranges are between 25 and Mostly hardwood shavings or sawdust 45 ºC while a heat of 60 ºC or over may are used like beech (Fagus silvatica), burn raw material. Average drying time is oak (Quercus sp.), robinia, (Robinia 5-8 hours which also depends on the thick- pseudo-acacia), alder and birch ness and water content of the fish. Too though in Southern countries ma- quick drying will form a hard crust on the hogany and cedar are attained as well. outer surface of the product though it re- It is not advisable to use trees of mains wet inside and may start spoiling. the pine family, grasses and peat- Too slow drying may develop a taint. Drying moss for fish smoking. is completed when the product becomes flexible and can be bent without breaking, Steps of fish processing 13

when cut up no moisture can be seen. spread mode of fish preservation. Mari- Figure 8: is relatively cheap to produce, nating is the preservation of fish meat with Air conditioner, easy to store and does not take up much table salt and acetic acid: fish are pre- refrigerator and storage space. About 10 kg raw material pared with pickling, or then hygienic means yields 1.5–2 kg dried product on average kept in spicy, salty, acidic pickling solution of transporting fish which is easy to pack and to transport. containing onion. Acetic acid makes fish are important Drying is widespread in Asia and Africa meat whiter and also shrinks it. devices of a fish and, lately, increasingly popular in . The salty-acidic pickling solution cures processing plant There is a fish specialty made of dried the fish, develops specific tastes and smaller fish and served with drinks. Dry- odours and changes meat texture. Acetic ing is a cheap, does not require expensive acid should reach a 2–5 percent concen- equipment and investments and requires tration in the solution, while curing is the little skill. It is recommended to dry fish on best with 3–9 percent table salt content. racks rather than on the ground due to the Temperature should be kept at 0 oC for op- shorter drying time achieved. In addition, timum results. The process takes 10–30 fish can be kept cleaner. days to complete, depending on the salt and acetic acid concentration. Marinating solutions feature cold, cooked, fried and 4.6.5  Marinating specially spiced sauces. Cold marinating starts with curing in a Increasing acid content in food and proper solution of vinegar and table salt thereby decreasing pH will inhibit vital then the is put into glass jars functions of microorganisms causing with spices and poured over with a salty spoilage. The most frequently applied vinegar solution. The best known product table acid which is also considered to be of this type is sprat. the most efficient is acetic acid. It does not Cooked marinating means that fish are destroy the micro flora in food, however, it cooked or braised in salty vinegar water. is a strong inhibitor to their proliferation. Then they are filled into boxes with liquid Acetic acid* also inhibits most enzymatic gelatin containing the cooking water, vine- activities but some enzymes still remain gar, table salt and spices. active. Thus, protease activity slows down Fried marinating begins with merging in marinated fish which assists in “curing” the cleaned fish in brine and flour and the fish product. Marinating is a wide- then frying it. When cooled down, fish are 14 SMALL SCALE TROUT PROCESSING METHODS

placed into a solution containing spices, 5  PACKAGING table salt and acetic acid. Special spiced marinating requires cold, cooked or fried marinated fish topp - The purpose of packaging is to protect the ed up with piquant mayonnaise, paprika, quantity and quality of the product from curry or mushroom sauces. production through the supply chain to the All marinated products are considered intended consumer. semi-preserved because vinegar and salt Using quality raw materials and ingredi- are not sufficient for killing microorgan- ents, modern machinery, skilled, conscien- isms. Therefore, they should be store on tious and well organized workers and 0-10 oC. production technology will result in quality products. This very product should then be transferred in its unchanged, original con- 4.6.6  Roe processing dition to the user or consumer. The original product condition can only be retained with Roe products are a high value product proper packaging. In cases when packag- made by separating individual eggs from ing becomes an element of the supply each other and from skein material chain – e.g. takes place in the trading loca- (screen ing), followed by in a satu- tion, – it becomes impossible to fully com- rated solution and curing (Bledsoe and plete its protective mission because the Rasco, 2006). Screening can be done product may be exposed to a series of haz- manually or using enzyme preparations ards from production to packaging. Un- rich in collagenase. After curing, roe is packed product may loose weight (in a graded for instance according to flavor and natural way as well, e.g. by desiccation), get colour, or even size. Roe is usually packed soiled or contaminated with insects or into plastic containers and frozen. mould. It is also an easy subject to pilferage. Therefore, it is practical to perform pack- aging operations at the manufacturing lo- Figure 9: cation of the product. As an added benefit, High tech small scale packaging should feature elements packing machine whereby it is easy to detect if it has been before loading and opened. If the original sealing has a visible with the product and unrepairable damage when opened ready to weigh the fact of opening can easily be seen. and label Gas-tight packing foils prevent oxygen infiltration and the escape of added gases. Oxygen would be vital for life functions of microorganisms while gaseous additives destroy them preventing the product to decay in quality. Packaging / Production offal 15

Freshly cleaned or smoked fish should of appearance (non-exposure of fat precipi- be packed in a designated packaging room. tation) and quality (light protection). The Freshly cleaned fish are transferred to the multi-colored graphic design of the tin sur- packaging room in dishes after washing and face is an added marketing value and ad- drip drying. They are prepared and por- vertising possibility. Fish products fully tioned on a corrosion-proof table then shrink shielded from consumer eyes do recruit wrapped into foil on trays or vacuum packed customers through brand trust alone. Tinned in sleeve pouches with protective gases products are able to find a steady market if (N2CO2). Similarly to preparation and cur- the manufacturer continues to be trustwor- ing, care should be taken during packaging thy, supposing that there are no fluctuations to prevent damages, soiling or contamina- in the quality of the packaged product. tion of the product and to ensure that it is protected with the packaging material. The packaging room should provide storage for not more than the daily quan- 6  PRODUCTION tities of packaging material. Additional stocks of packing materials should be OFFAL stored in a separate dust-free room not exposed to insect or rodent hazards or Fish processing yields offal. Its quantity other ways of contamination or spoilage. varies with the size of the fish, processing Packaged products should be labelled. and preparation methods and ranges be- The most important characteristics of the tween 15-60 percent. product such as product name, name and Certain by-products of fish processing address of the manufacturer, date of pro- may be converted to products suitable for duction, shelf life date, recommended stor- human consumption e.g. filleting residues age temperature and net weight should like and backbone yield 3-8 per- appear on the label of the retail packaging. cent meat pulp after meat-bone separa- Retail packages should then be tion or they may be simmered to fish stock wrapped in wholesale boxes and placed with various ingredients. in cold storage at required temperature. Materials unsuitable for human con- There is a wide range of different types sumption and pieces that have fallen on and brands of fish packaging machines the floor or soiled in any other way during which can be purchased worldwide. Fresh processing should be treated as offal. or smoked fish can be packed with vac- Offal should be collected in a way not to uum packaging or gas flushing machinery. cause contamination. Products unsuitable for Gas flush packaging is rapidly gaining human consumption shall be clearly marked popularity in recent years. Such machines as such (with a red stripe or labelling). require a special, impermeable foil which Offal should be collected in dedicated does not let the molecules of the protec- storage containers in the plant. Depend- tive gas to pass through. ing on quantities, offal should be trans- Deep frozen finished products are ferred to storage containers whenever it is packed in PE (polyethylene) pouches and accumulated during a shift but at least at sealed. Pouches may bear colored the end of each shift. Storage containers graphic design. Retail packages are col- should be located in the cold storage of lected in large cardboard wholesale boxes the service building. then tied around with plastic bands. The Temporary storage should be designed boxes bear self-adhesive labels on their in a way not to allow the contamination of side with basic product characteristics and food or drinking water. Access by insects, storage temperature on them. rodents, birds and domestic animals to Marinated fish products are mainly mar- storage containers should be prevented. keted in small plastic boxes, buckets or Both storage location and containers glass jars while most of the fully preserved should be cleansed and disinfected after fish products are packed traditionally into emptying. Offal storage should be re- tins (lacquered, tin-coated steel or alu- moved from the plant each day with a ded- minium sheet). It is appealing both in terms icated vehicle. 16 SMALL SCALE TROUT PROCESSING METHODS

6.1  OFFAL QUANTITY  REFERENCES AND TREATMENT

Blood, intestines and gills as well as Allaby, M. 1994. The Concise Oxford scales and skin should be stored in a ded- Dictionary of Ecology. Oxford icated, closed plastic container in the University Press. preparatory room. This offal container Brainerd, S.M. 2010. European Charter should be emptied whenever filled up and on Angling and Biodiversity, also at the end of each shift. Intestines Presentation of NINA1 and ESUSG2 have to be stored open-air in closed con- specialist on 9 April 2010, tainers in a washable area paved with Strasbourg, FRANCE concrete. They should be removed from Bledsoe,G. and Rasco.B. 2006 – the plant each day with a dedicated vehi- and Fish Roe in Handbook cle or placed into cold storage until dis- of Food Science, Technology and posal from the plant. It is recommended Engineering. Volume 4. (Ed) Hui, that a waste management plan is enacted Y.H., CRC Press. Florida. USA throughout the processing facility. CAC (Codex Alimentarius Commission), 2001 – Food Hygiene Basic Text. 2nd edition. Food and 6.2  OFFAL PROCESSING Agriculture Organisation / World INTO FISH SILAGE Health Organisation, Rome, . Hoitsy, Gy. 2002. A Pisztráng Table 3: tenyésztése és horgászata, 152p. Large quantities of offal unsuitable for Treatment of fish Thain, M. and M. Hickman, 1980 – The human consumption can be utilized after offal with sulphuric Penguin dictionary of biology, processing into animal feed. acid Penguin Books Huss, H., Dillon.M., and Derrick, S. Minced fish offal: 98.1 kg 2005 – A Guide to Hygiene Management. – Accessing 1.3 kg 80% sulphuric acid solution: the European and American Potassium pyrosulphate (K2S2O5): 0.6 kg Market. Sippo/Eurofish. Welcomme, R.L. 2001 – Inland , ecology and management. FAO. Offal remaining after cleaning fresh fish Blackwell Science Ltd. has to be minced. This may be completed Wheaton, F.W. and Lawson, T.B., 1985 with a hammer grinder and then the prod- – Processing aquatic food uct should be passed through a sieve of products. John Wiley & Sons, 5–8 mm mesh size. Following heat treat- Toronto, CANADA ment the pulp should be mixed with tradi- tional feed (wheat, cornmeal) then it becomes suitable for feeding fish. The ground, minced pulp may also be treated with an 80 percent sulphuric acid solution to yield a product of 1 percent acid concentration. Fish offal pulp treated with preserva- tives should be stored in closed contain- ers (barrels). Cooked and dried fish offal may be ground into . Its nutritive value varies with the quality of the offal. As a rule, 4 units of offal yield 1 unit of fish meal.

1 Norwegian Institute for Nature Research 2 European Sustainable Use Specialist Group References / Glossary / Annex 1 17

 GLOSSARY ANNEX 1

Acetic acid CRITERIONS OF A MODERN The acid which gives vinegar its charac- FISH PROCESSING PLANT teristic taste. Brine 1  General hygiene Water containing dissolved salt. requirements Hygroscopic A substance which absorbs moist Providing safe food, free from contamina- from its environment. tion for human consumption, is important Natural fish food to ensure effective food control (Huss et al., The collective name of all those 2005). Good Hygiene Practices (GHP) are dead or living organisms and or- all the practices regarding the conditions ganic materials which grow/develop and measures necessary to ensure the in natural and man made water bod- safety and suitability of food at all stages of ies and is consumed by fish. In case the food chain (CAC, 2001). In fish pro- of trout * aquatic insects zooplankton cessing, it is important to maintain hygiene and their larvae, fish and fish larvae in order to maintain quality of fish. This is and any smaller aquatic and terres- not only limited to the fish itself, but also trial animals which can be grabbed covers the processing facility, processing and consumed by trout. equipment and the workers in the facility. Zooplankton It is the collective name of tiny worms Figure 10: and insects swimming passively or Personal hygiene of actively in the water. In other words it workers starts at means the animal members of the the proper storing plankton (Thain and Hickman, 1980). of their clothes

There are general hygiene requirements applicable in most countries which should be known and observed. When designing a processing plant it is essential to allocate sufficient work space to allow proper com- pletion of work processes in accordance with hygiene requirements. Work phases 18 SMALL SCALE TROUT PROCESSING METHODS

should be planned in a way to prevent prod- from wall-mounted containers should be ucts being soiled. Therefore a clear separa- used for drying hand. tion of clean and dirty zones is required. Staff rooms and toilets should not have Material flow within the facility should be so direct access to processing rooms. Clean- designed that cross-contamination is pre- ing materials and disinfectants used for vented as much as possible. For instance, cleansing should be stored outside the cleaned fish should be kept away from non- production rooms in a well ventilated cup- cleaned fish, just as cooked fish should be board in a separate place. kept away from raw fish. A separate water discharge facility The design of a food manufacturing fa- should be installed for cleansing purposes cility should permit proper cleansing and equipped with special valves which pre- disinfection. For this reason flooring vent the backflow of water in the pipes. should be covered with impermeable, Utensils, such as knives and cleavers easy to clean and disinfect materials (con- used for fish processing should be regu- crete > waterproof > anti-slip floor tiles/ larly cleaned and disinfected at least once slabs). The floor should be properly drain- after each work shifts. For this purpose a able into the sewage system in order to disinfecting facility with hot water of mini- keep it clean and completely dry. mum 82 oC should be provided. It is rec- Walls should have smooth, easy to ommended that a written cleaning plan is clean, waterproof surfaces (tile cover) up drawn up and included in the processing to the ceiling in technological rooms and facilities in-house control plan, where for up to a height of 2 m in all other rooms. instance, the chemicals and disinfectants Doors and windows should also be easy to be used are determined, as are the to clean. Inner window sills should have a amounts, mode and frequency of cleaning slope of 45 degrees. Windows should be and the persons responsible. covered with mosquito net on the outside. Proper lighting is essential as well. In ad- dition to natural light work tables in the gut- 2  Rodent and insect control ting room should be illuminated with 540 lux, in other rooms with 310 lux. Lamps are Regular, planned and timely executed to be placed and arranged in a way to pre- pest control is essential which should in- vent shading at work processes. clude preventive, control and at infected Proper aeration of a food production fa- places eliminating measures as well as cility should be ensured partly by natural their preset timing. Pest preventive, con- aeration, partly by artificial ventilation. The trol and protective actions should be ac- latter should include air conditioning in curately documented. rooms where fish cleaning, cutting, curing Rodent elimination should possibly be and packaging take place. These working coordinated with neighboring sites and re- processes require a temperature below 12 peated if and when necessary. Neverthe- oC. Ventilation of the lavatory and shower less, the placing of poisonous baits cannot rooms should be done with an air sacking interfere with or jeopardize food produc- fan for discharging used air to the outside tion, processing or trade and their location of the building. where poisonous substances are not per- The entrance should be equipped mitted. Accordingly, bait spots should be with boots and an apron washer. A fish carefully identified. Positioning of the num- processing plant should include chang- bered rodent box traps within the buildings ing rooms dimensioned and equipped in and throughout the entire plant should be accordance with standards and regula- marked in a map. Box traps should bear tions. Sanitary requirements of places Arabic numbers starting with 1 and up, as where hot and cold running water is well as a warning sign. They must be lock- available should also be observed and able and made of weatherproof material. maintained. They should feature entry and exit open- Technological rooms should feature ings as well as a dividing partition. The foot-pedal operated hand washing facili- floor of the box should be covered with ties. Disposable paper towels available fine sand to allow detection of eventual in- Annex 1 / Annex 2 19 vaders. Poisoned baits should be placed ANNEX 2 in a way to prevent scattering and also to permit the precise follow-up of their con- sumption. To track pest/rodent presence opera- PRODUCT SHEETS OF FRESH AND tors should complete weekly visual SMOKED TROUT checks of numbered box traps and keep records of bait and poison consumption. Should there be no consumption still a NAME OF PRODUCT chemical treatment of the space is re- Processed fish: Fresh trout quired twice a year whether the area is pest contaminated or not. Quality requirements Appearance: Skin is intact and its colour is char- Where insects are a threat their elimi- acteristic to the species. It may vary from silver- nation should be carried out at least twice white to dark-gray. It is well cleaned, free of dirt and any possible contamination. Colour of flesh a year or whenever necessary. The appli- varies from light-pink to reddish. cation of poison must not interfere with or Taste: Free of any strange flavour, clear light jeopardize food production, processing or flavour of fish. trade nor their location. Unpacked food Smell: Free of any strange odour, clear light odour of fish. must be removed and placed in safe place Consistency: Elastic touch of flesh, crispy if cook ed during the application of insecticides. They or fried. should be properly protected. Following in- Mode of preservation Packing with gas: 30% CO2 and 70% N2 sect destruction surfaces which may con- Expiry date 7 day from packing tact with food must be checked for Packing Single packing: Fish placed on polystyrene tray residues of poisonous substances. and covered with gas retaining folia. Parameters of packing materials: Number of trad- ing permission and name of producer 3  Personal hygiene Whole packing: Identification of the type of a car- toon box It is essential to maintain worker hygiene Indication of packing Single packing with label unit in the processing plant. Staff in contact Storage Storing between 0–5 °C (It should not be longer with food must keep personal hygiene in than 1/3 of the entire lifespan of product). every respect, wear clean work clothes Costumers’ target For the entire population directly from retailers. and protective gears where required groups such as hair and beard net, mask, etc to Possible improper use Interruption of cool-chain anywhere between pro- prevent hair, microbes etc. from falling duction and consumption. into the fish products. Protective clothing Consumption beyond date of expiration. is essential when working, and clothing Improper preparation in the kitchen including the and footwear should also be regularly lack of cooking or frying. wash ed. Visitors to the processing facility Transporting condition In special vehicle equipped with cooler which should also be required to wear protec- guaranties required temperature 0–5°C. tive clothing. Recommendations for Store between 0–5°C (no longer than 1/3 of the wholesalers entire lifespan of the product). Equipment for cleaning and disinfect- and retailers Instruction on label ing hands should be located nearest to Recommendations Consumption before: work places. No manually operated taps for costumers Recommended ways of preparation: are permitted. Hot and cold running Contents of label Produced by: Name, location and EU number water should be provided. Staff engaged Packed by: Name, location and phone number in cutting fish or handling and preparing Type of product: raw materials and products should start State of preparedness: Way of packing: each work shift in clean protective cloth- Date of production: dd/mm/yy, Date of expiration: ing. If necessary it should be changed to dd/mm/yy a clean one even before the end of a Recommended temperature to store: shift. Staff must wash and disinfect Net weight: Unit price: hands at the start of each work shift and Price: should repeat it several times during Particulars of producer Name and location working hours. 20 SMALL SCALE TROUT PROCESSING METHODS

NAME OF PRODUCT ANNEX 3 Processed fish: Smoked trout

Quality requirements Appearance: Skin is intact, well cleaned and free of dirt. Due to smoking its colour varies from light LIST OF RECOMMENDED golden-yellow to bronze brown. Colour of flesh FURTHER READINGS varies from light-pink to reddish. Taste: Free of any strange flavour, clear light OF RELATED LITERATURE flavour of smoked fish. Smell: Free of any strange odour, clear light odour PUBLISHED BY FAO of smoked fish. Consistency: Elastic touch of flesh and crispy. Bykowski, P.; Dutkiewicz, D. 1996. Mode of preservation 10% brine, smoking and packing with gas (30% CO and 70% N ) Freshwater fish processing and 2 2 equipment in small plants. Expiry date 30 days FAO Fisheries Circular. No. 905. Rome, Packing Single packing: Fish placed on polystyrene tray FAO. 1996. 59p and covered with gas retaining folia. Parameters of packing materials: Number of trad- (http://www.fao.org/docrep/w0495e ing permission and name of producer /w0495E00.htm) Whole packing: Identification of the type of car- CAC (Codex Alimentarius toon box Commission), 2001. Food Indication of packing Single packing with label Hygiene Basic Text. 2nd edition. unit Food and Agriculture Organisation Storage Storing between 0–5 °C (This period should not / World Health Organisation, be longer than 1/3 of the entire lifespan of product). Rome, Italy. Costumers’ target For the entire population directly from retailers. Guevara, G.; Abella, F.F.; Marfori, E.A.; groups 1976 Utilization and processing of Possible improper use Interruption of cool-chain anywhere between pro- duction and consumption. . Indo-Pacific Fisheries Consumption beyond date of expiration. Council. Symposium on the Improper preparation in the kitchen including the Development and Utilization of lack of cooking or frying. Inland Resources, Transporting condition In special vehicle equipped with cooler which Colombo (Sri Lanka),27 Oct 1976 / guaranties the required temperature 0–5°C. FAO, Rome (Italy). Fisheries Dept. Recommendations for Storing between 0–5 °C (This period should not , 1976 , 10 p. wholesalers be longer than 1/3 of the entire lifespan of the Lamendour, P.M.; 1983. Improvement of and retailers product). Fisheries and Aquaculture Recommendations Consumption before: for costumers Recommended ways of preparation: Production Project, Syrian Arab Republic. Handling, processing Contents of label Produced by: Name, location and EU number Packed by: Name, location and phone and marketing of fish. Type of product: Field document, FAO, Rome State of preparedness: (Italy), 1983 , 19 p. Way of packing: http://www.fao.org/docrep/field/003 Date of production: dd/mm/yy, Date of expiration: dd/mm/yy /Q3832E/Q3832E00.htm Recommended temperature to store: Zhao Yimin; 1994. Marketing of rainbow Net weight: trout in China. FAO, Rome (Italy), Unit price: Price: 1994, 12 p. (http://www.fao.org/docrep/field/00 Particulars of producer Name and location 3/AB903E/AB903E00.htm) The FAO Regional Office for Europe and Central Asia Benczur utca 34, H-1068 Budapest, Hungary