A. F I S H M A R K E T S
O n t h e E u r o p e a n Atlantic coast and in some parts of the United States, it is c o m m o n to land fish at a market (fish p i e r ) where it is put up for auction. T h i s procedure is convenient for the ship and normally se
cures the maximum price for the fish. T h e s e auctions, however, frequently cause delay in the further distribution of the fish, w h i c h is detrimental to quality. At most markets there is only one sale p e r day, as a rule early in the morning. This fits into a certain rhythm, which includes a routine distribution system (special fish trains, e t c . ) w h e r e b y the fish reach the inland wholesale or retail dealer in time for further sale, at best on the following morning. At some markets (e.g., in D e n m a r k ) , there are several sales during the day if n e e d b e . This means that the fishing boats and fish have a shorter waiting time.
1. Unloading
If fish are iced in the fishing vessel they should b e kept there until the time of auction in order to limit the normally unavoidable rise in temperature of the fish during t h e time spent in the market.
I n several ports fish are sold while they are still lying in the boat and are only unloaded w h e n they are to b e moved to the packing house or processing plant. This procedure is obviously of great advantage if the fish are stored in ice. I n most cases, however, the fish are unloaded b e fore being sold.
It is essential to unload as quickly as possible. In contrast to the
method often used in canneries and reduction plants, w h e r e fish are p u m p e d or transported b y conveyors from b o a t to plant, t h e practice at market piers of unloading fish in baskets or boxes that a r e hauled ashore by winches, is slow. B i g trawlers, for instance, must b e g i n unloading 1 0 - 1 2 hr. before t h e auction starts. T h e r e is obviously m u c h room for improvement here ( M e i n e r s , 1 9 5 5 ; F r e y b e r g , 1 9 5 5 ) . I n the principal fishing ports of the Soviet Union, m e c h n i c a l unloading devices have b e e n introduced that utilize pumps, hydrotransporters, and flumes ( T e r e n t j e v , 1 9 5 7 ) .
2. Handling in the Market
After sorting, bulk-iced fish are usually filled into special market boxes or kits, where they remain during the sale until they are either processed in a plant or r e p a c k e d b y the merchants into other shipping containers for subsequent transport elsewhere.
It is a c o m m o n rule that fish put up for sale at a fish market b e free of ice. It is claimed that ice prevents the buyer from getting a full view of the fish, which, as mentioned earlier, is principally b o u g h t on appear
ance. All the same, ice has b e e n introduced into several fish markets without noticeably preventing the buyer from judging t h e quality. At any rate, one could safely use ice at the b o t t o m of the boxes.
T h e results of temperature measurements at markets w h e r e fish are put up for sale without ice ( s e e F i g . 14, discussed in this section, B , 4 ) , indicate that some fish have a temperature of about 1 0 ° C . / 5 0 ° F . for at least 12 hr. ( B u r g e s s , 1 9 5 8 ) . Similar results are reported from other sources. I t is n o w well known that fish spoil about 5 times as fast at 1 0 ° C . / 5 0 ° F . as at 0 ° C . / 3 2 ° F . ( s e e Section Ι Ι , Ε ) . I n other words, fish lose about 2τ/2 days' storage life in passage through the fish market. F r e y -b e r g ( 1 9 5 5 ) rightly emphasizes that although the modern super motor trawler has at its disposal 5 0 0 h.p. m o r e than t h e old-fashioned, 1000-h.p.
steam trawler, and c a n thus gain, e.g., 17 hr. on an I c e l a n d round trip, thereafter 2 or more days can readily b e lost at the fish market.
An interesting suggestion for rapid cooling of fish in boxes while they are standing in the market hall comes from Germany, w h e r e a snow-ice m a c h i n e was used experimentally for boxes of fish. T h e results are indi
cated in the following tabulation ( B i e r m a n n , 1 9 5 6 ) .
Fish temperature Time Air temperature Snow-iced Not iced 9 P.M.A 11.5°C./53°F. 2.5°C./36.5°F. 2.5°C./36.5°F.
1:45 A.M.
—
1.5°C./34.6°F. 4°C./39.2°F.7 A.M.0 11.5°C./53°F. 1°C./33.8°F. 5°C./41°F.
a Unloading.
& Auction starts.
In some markets it is possible to stack the fish boxes two or more high.
This appreciably diminished the flow of heat into the fish.
W h e n fish such as herring, mackerel, sprat, and inshore w h i t e fish are packed in boxes at sea, it is c o m m o n to use these boxes as containers in the market hall and, after they have b e e n replenished with ice, during the subsequent distribution. I n this w a y t h e fish is handled as little as possible and thus retains a better appearance.
3. Market Containers: Material and Hygiene
W o o d is still the most frequently used material for market containers.
Along with the knowledge that bacteria are the main cause of fish deterio
ration, however, has c o m e an understanding of the problems of hygiene related to these wooden containers.
Microbiologists h a v e found that the inside of such boxes m a y contain several hundred millions of b a c t e r i a per square inch even after applica
tion of water from high pressure jets. It is necessary to use a strong disinfectant, e.g., a hypochlorite solution containing 1 0 0 0 p.p.m. free chlorine or a quaternary ammonium compound, 0 . 1 - 1 % strength, to obtain a considerable reduction ( 9 9 - 9 9 . 9 % ) in t h e bacterial count, and even then old boxes m a y still have hundreds of thousands of bacteria per square inch left, particularly just b e n e a t h t h e surface ( S p e n c e r , 1 9 5 9 , 1 9 6 0 ) . I t is a c o m m o n practice, w h e n e v e r possible, to let the cleaned wooden fish boxes stand in t h e sun for a few days so that they c a n dry.
Investigations of this procedure showed that it led to no improvement ( S p e n c e r , 1 9 5 5 ; Kreuzer, 1 9 5 6 ) .
T h e conclusion from this work is that it is almost impossible to clean satisfactorily heavily contaminated wooden surfaces. An aggravating factor is that fish-filled market containers often remain at the processing plants for several days before b e i n g returned to the market. I f the fish are in direct contact with t h e wood during such periods, unpleasant flavors from the wood m a y b e transferred to the fish (Anonymous, 1 9 6 2 a ) .
It is a strange paradox that, whereas fish rooms in ships are kept well painted and fish packing premises ashore are m a d e with smooth, imper
m e a b l e walls, floors, and tables, yet fish is held for hours or even days in moist absorptive bacteria-loaded wooden boxes. This explains t h e recent shift to alluminum-alloy containers or to wooden boxes enamel-coated on t h e inside. T h e idea of using painted boxes is not really new. S u c h boxes have, for instance, long b e e n in use in the Norwegian canning industry for the transportation of sprat and herring from the landing places to t h e canning plants; see also this section, B , 2 .
Spencer ( 1 9 6 1 ) compared n e w resin-coated and uncoated wooden fish boxes and found that the coated boxes w e r e less contaminated b y
fish and w e r e generally cleaned more efficiently b y t h e various methods examined.
R e c e n t years have also brought about b e t t e r cleaning equipment for boxes, w h e t h e r aluminum or wood. I n Grimsby, machines with a capacity of 4 0 0 0 boxes p e r 8-hr. day are in use. T h e boxes are subjected to a cold water rinse, a steaming, a hot w a t e r ( 9 4 ° C . / 2 0 0 ° F . ) wash, a cold water rinse, and finally a brief h a n d scrubbing. A m a c h i n e used in Bremerhafen, with a capacity of 8 0 0 0 boxes p e r 8 hr. works without steam. T h e treat
m e n t consists of a short spray of cold water inside t h e b o x to remove gross dirt; an extensive cold pre-rinse from jets at 7 a t o . / 1 0 0 l b s . / s q . inch
( u s i n g re-circulated cold w a t e r ) ; a m e c h a n i c a l brushing o f t h e sides and bottom of the box; a short rinse with high-pressure ( 3 0 a t o . / 4 5 0 l b s . / sq. i n c h ) clean cold water, and finally a short disinfectant spray.
T h e B r e m e r h a f e n fish market uses another m e t h o d o f cleaning. Boxes standing in a single layer in t h e market hall are first hosed with water;
thereafter sprayed with very fine jets of an ampholytic soap disinfectant ( s e e also Section I I I , E , 5 ) , and finally, after 2 0 - 3 0 min., are again hosed with a strong water-jet ( W e g n e r , 1 9 5 5 ) .
S u m m i n g up this important subject of cleaning fish boxes and other surfaces in c o n t a c t with fish, it is r e c o m m e n d e d , w h e r e possible, to b e g i n the operation b y removing fish slime and dirt with a strong detergent
(e.g., soda or t r i p h o s p h a t e s ) , preferably using w a r m water, and to finish b y cleansing with a disinfectant.
B . D I S T R I B U T I O N
F i s h intended for distribution as fresh and unprocessed are usually brought from the market or other landing points to a packing house. T h e y are i c e d or re-iced and m a d e ready for transport to the wholesaler or retailer.
1. Is Washing Effective?
T h e r e is widespread belief that slime on fish acts as a preservative and that washing is therefore detrimental. F i s h are thus seldom washed before b e i n g p a c k e d for distribution.
O n t h e other hand, since slime is an excellent culture medium for fish-spoiling bacteria, and since fish w h e n landed often carry a load of several million b a c t e r i a p e r square inch of surface—organisms that do not penetrate in large numbers into the fish until fairly late—it would b e only natural to think that t h e slime should b e removed as completely as possible.
I n view of the fact that it is feasible b y effective washing to r e m o v e
up to 9 9 % of the bacteria on the fish, it is remarkable that the keeping quality of the fish is not essentially improved (Castell, 1953b; R i e m a n n and Bramsnaes, 1 9 5 4 ) . O n the contrary, there are indications in these experiments that the quality of the fish deteriorated more quickly after washing. T h e species examined were small and medium-sized cod. It m a y b e that better results are obtainable with larger fish. A wash in chlorine-water seems to have a beneficial effect on the keeping quality of sharks (Hjorth-Hansen and Bakken, 1 9 4 7 ) .
2. Boxes for Fish
A great variety of containers are available for packing fish. Such con
tainers must m e e t several requirements, the most important of w h i c h are the following: the size of the container must b e suitable for t h e fish to b e p a c k e d in it; the container should b e easy to handle and ship b y ordinary means of transportation; it should b e strong enough to with
stand the strains of transportation; and the material used for the con
tainer should have insulating properties sufficient to prevent excessive melting of ice. W a t e r from melting ice must b e able to drain away. I f containers are "non-returnable," their price must b e low. I f they are
"returnable" or are to b e re-used in some other w a y for fish, the material should b e readily cleanable.
W o o d e n boxes are t h e most widely used containers. T h e y have the advantage of being good insulators and in m a n y countries are reasonably priced, compared with other materials. In Scandinavia, wooden boxes are comparatively lightly built, mostly of unplaned wood, since they are not usually returnable; if they are returnable ( a s in domestic t r a d e ) , they are used again only a few times. In some countries where it is customary to return the containers repeatedly, they are often m a d e of thicker, planed wood. Plain wood is admittedly a rather primitive material for packing perishable foods. M u c h time, therefore, has b e e n spent on finding a better container.
T h e Hull liner crate, in spite of its early promise, has now almost passed out of use. It consisted of a lidless aluminum b o x with small drainage holes, which for protective and handling purposes was fitted in a wooden crate with an aluminum-lined, wooden lid. T h e latter was secured with spring fasteners that obviated the use of nails. T h e fasteners also acted as reinforcing bands offering protection against damage. Vari
ous reasons have b e e n advanced for the failure of this box, among which m a y b e mentioned: cost; difficulty in keeping the crate clean ( i t b e c a m e fly-infested in the w a r m w e a t h e r ) ; and lack of strength of the inner aluminum lining.
In many areas, as has b e e n the case with fish market containers,
wooden boxes for distribution have b e e n improved b y b e i n g sprayed on the inside with a white plastic coating.
Several types o f all-aluminum boxes are n o w in use. B e c a u s e of their poor insulating properties they are not r e c o m m e n d e d w h e n boxes are exposed individually to air temperatures for long periods; but where delivery takes p l a c e in whole car- or truck-loads, there is no n e e d for a container of insulating material and advantage c a n b e taken of t h e ex
cellent hygienic properties of the metal.
T h e possibilities of using resin-impregnated w o o d or plastic reinforced with fiber glass are also b e i n g investigated (Anonymous 1 9 5 7 c ) .
Cutting et al. ( 1 9 5 6 ) h a v e tested various returnable boxes together with several proposals for non-returnable ones. As regards the former they found that t h e normally used wooden boxes could b e considerably strengthened if the sides w e r e reinforced b y steel straps. T h e non-return
able boxes w e r e m a d e of corrugated fiber-board, expanded polyvinyl chloride and resin-impregnated paper pulp. T h e latter was found most promising.
3. Tacking Fish
W i t h regard to rates of cooling, the reader is referred to Section V , Β , 1, and to the theoretical calculations and experimental results obtained b y Nicol ( 1 9 5 8 a , b ) . I t is imperative that the fish b e cooled before t h e boxes are finally p a c k e d with ice. Normally this is done b y icing the fish in the boxes, w h i c h are thereafter left standing in the packing house until the temperature in the fish is about 0 ° C . / 3 2 ° F . T h e containers are then re-filled with i c e and kept full until dispatch. During such cooling and possible subsequent storage the boxes are advantageously stacked on top of each other with the stacks close together. T h e amounts of ice required depends on m a n y factors, such as season, length of voyage, and m e t h o d of transportation. I t is c o m m o n to use from 2 5 to 1 0 0 % of the weight of the fish. T h e type of ice—crushed ice, scale ice, snow-ice— is often the subject o f discussion. I f c o m p a r e d b y weight, there does not seem to b e any great difference in t h e resulting cooling. I t should b e noted, however, that t h e volume taken up b y equal weight of various types of ice is not the same. T h i s leads sometimes to erroneous conclu
sions.
It is well known in t h e trade that certain fish, such as c o d and flounder, take on a speckled a p p e a r a n c e w h e n stowed or p a c k e d with ice. T h e speckles are due to t h e b l e a c h i n g of the skin pigment on surface areas in contact with ice particles. T h e original skin color can b e restored to some extent b y exposing the fish to air or cold, clean water. I n order to retain good color and bloom, however, c o n t a c t with ice is sometimes
avoided. This accounts for the "shelving" of fish on b o a r d ship and for the practice in some countries of using a layer of parchment paper b e t w e e n fish and ice w h e n fish are p a c k e d in boxes.
O n shore as well as at sea, temperature is the chief factor influencing the freshness of fish that reaches the consumer. P r a c t i c e has shown that
FIG. 1 4 . Diagram of the temperature history of fish during distribution, based on thousands of readings. The bottom line shows the lowest, the top line the highest, temperatures recorded (Burgess, 1 9 5 8 ) .
to 3 0 ° F . , during inland distribution. An extensive investigation of this problem m a d e in the United Kingdom m a y serve as a valuable guide for conditions elsewhere ( B u r g e s s , 1 9 5 8 ; Burgess et al., 1 9 5 9 ) . I n all, nearly 30,000 temperatures of wet fish w e r e taken at all stages in t h e distribu
tion chain. I n F i g . 14, the bottom line shows the lowest recorded tempera
tures at e a c h stage in the chain, the top line, the highest recorded tem
perature. O n e half of all readings taken lies in the middle range. T h e
curves included b o t h whole fish and fillets. T h e latter w e r e often a few degrees w a r m e r than the whole fish since the fillets w a r m e d up during handling on the filleting table, in rinsing vats, etc.
5. Fish Transport
I n choosing the facilities for transporting fish from place to place the fish dealer is faced with two extreme cases. T h e size of e a c h lot under transportation m a y vary greatly, from one or two boxes to entire car
loads or ship-loads.
In the first case, the situation is very difficult w h e n the w e a t h e r is warm and the journey of considerable duration. E v e n if fish are well cooled and p a c k e d together with plenty of ice, they are fairly soon with
out ice and at the m e r c y of the outside temperature, and are subject to rough treatment since the container is not full.
T h e problem of consignments of 1 0 0 - 2 0 0 lbs. of fish is sometimes solved b y placing a f e w boxes together with i c e in a larger box. In Canada, insulated, iceless, refrigerated, fresh-fish containers have b e e n tried. Refrigeration is supplied b y eutectic solution of sodium sulfate
contained in sealed r u b b e r tubes (Anonymous, 1 9 5 3 c ) .
Railway-car and truck-loads are usually dispatched in insulated vehi
cles, in E u r o p e in so-called "thermo-vehicles;" the latter are insulated b u t not mechanically refrigerated.
A c o m m o n procedure is to stack the boxes with iced fish in the car or truck and to p l a c e sufficient ice on the top and at the sides to absorb the heat penetrating from outside during the trip. In order to take other perishable foods, m a n y of these vehicles have ice bunkers placed at t h e ends or in the roof. W h e n fresh fish are transported, the ice serves its purpose best w h e n p l a c e d directly on the load of fish.
T h e amount of i c e required and the best w a y of deploying it will vary with the type of car, its construction, insulation, heat bridges, the outside air temperature, length of the trip, etc. In short, one has to find out b y experience.
I n m a n y cars and trucks the floor, for various reasons, is not insulated.
I n such vehicles it is r e c o m m e n d e d that for long journeys a layer of ice b e p l a c e d on the floor before the boxes are stacked. T h i s layer m a y con
sist of blocks of ice.
S n o w i c e machines w h i c h spread this i c e b y blowing facilitate the covering of the tops and sides of fish loads.
W a t e r - i c e is commonly used for the a b o v e purposes. However, dry ice (solid carbon dioxide) is frequently a d d e d as a supplement or to replace some of the water ice, b u t as far as information can b e gathered this is only done in a very haphazard manner. T o replace the cooling capacity
of, e.g., 1 ton of water ice, nearly ^2 ton of dry ice is required, b u t in practice m u c h less is used b y the trade. This is not surprising, b e c a u s e dry ice is, weight for weight, about 3 0 - 5 0 times as expensive as water ice.
C a r b o n dioxide, in conjunction with normal i c e storage, is an effective bacterial inhibitor in concentrations exceeding 4 0 % . I t has t h e disadvan
tage that the fish tend to b e c o m e soft in texture and unattractive in appearance with this p e r c e n t a g e of C 02 ( R e a y and Shewan, 1 9 4 9 ) . Awareness of the preservative effect of C 02 m a y explain the use of dry ice in fresh fish transports. I n recent J a p a n e s e experiments two railway-car loads of mackerel iced in boxes were compared, where one railway-car h a d 1 ton of w a t e r i c e , t h e other 1 0 0 kg. of dry ice, on top of t h e load. T h e experiments w e r e not conclusive as to the quality of t h e fish, but it is interesting that in t h e course of 10 hr. the concentration of C 02 in t h e car with dry ice r e a c h e d 4 0 % measured at t h e top and b o t t o m of t h e load ( M a t s u d a , 1 9 5 8 ) .
6. Retailing
W h e n the retailer receives fish, they have often b e e n subjected to a chain of events outside his control. F i s h temperature is a primary con
cern of t h e retailer, w h o must b e a b l e to store chilled fish during t h e day. Moreover, h e will sometimes inevitably have fish "left over" from the day's sale. Therefore, insulated chill rooms, ice chests, or boxes with or without m e c h a n i c a l refrigeration, and a sufficient supply of i c e are essentials.
During opening hours, a representative selection of fish for sale must b e displayed in t h e shop before customers. T h e s e fish are not covered with ice and if no precautions are taken the temperatures in the fish often rise to the region of 1 0 - 2 0 ° C . / 5 0 - 6 8 ° F .
I f the fish are p l a c e d on trays with a little ice or laid on blocks of ice on the slab, lower temperatures can b e reckoned with. Burgess et al.
( 1 9 5 9 ) found that t h e difference in average temperature b e t w e e n wet fish on the slab with a n d without ice was of the order of 5 ° C . / 9 ° F . T h e y also investigated the use of refrigerated slabs and cabinets, which seemed disappointing in performance and less effective than liberal icing. Refrig
erated display counters of suitable construction are, however, success
fully used in some countries.
T h e "ambulant" fishmonger selling his goods in rural districts from a motor car or other vehicle, is not confronted with the disadvantages of a display counter. O n t h e other hand, the temperature problem on the whole is even worse here. T h e fishmonger does solve a great part of it b y having his vehicle fitted with an insulated container in which the ice on the fish will keep well. S u c h containers are b e c o m i n g more and more
common. ( R e g a r d i n g fresh fish sold in self-service stores, see this sec
tion, B . ) VII. Fish Fillets
W i t h i n the last 3 0 years filleting has b e c o m e widespread. I n some of the b i g E u r o p e a n ports, up to 8 0 % of t h e fish distributed inland in the fresh state is filleted before dispatch. T w o main reasons for this are the trend towards kitchen-ready products and the savings h a d b y transport
ing 5 0 - 7 0 % less weight, c o m b i n e d with the use of fish offal in fish meal
ing 5 0 - 7 0 % less weight, c o m b i n e d with the use of fish offal in fish meal