New and delicatessen products
New products
With the rapidly expanding world population and limited size of
the world's food resources, it is becoming increasingly important that all fish
resources should be fully used. It is estimated that, for instance, 5 000 000
tonnes of shrimp by-catch are wasted each year when they are thrown back into
the sea. Similar quantities of presently unmarketable and unpopular fish are
wasted in other areas. Considerable quantities also of fish offals and waste are
either completely wasted or turned into animal feeds or fertilisers. These
products have a less significant effect on human nutrition than they would if
used directly for human consumption. The search for new products able to make
use of these otherwise wasted fish is a continuing one. The products must be
acceptable to a consumer willing to pay the price of the processing involved in
their production. Presently, the most active field of research and development
is the use of fish minces.
Fish minces
The flesh from species of fish which are unmarketable as whole
fish or in conventional fish products can be used as a mince. The removal of
flesh and subsequent mincing disguises the original nature of the fish and the
consumer may well accept a product made from the fish mince when he would not
have accepted the original whole fish.
Production of the mince
It is feasible for the flesh to be removed from the fish using
hand tools such as filleting knives and then passed through a conventional meat
mincer (either hand-operated or powered by an electric motor). On a small scale,
and where relatively large fish are concerned, this may well be the most
economical way of producing the mince. However, many of the fish that might be
used for production of minces are small and occur in relatively large quantities
(e.g., shrimp by-catch). Under these circumstances, it may be more advisable to
contemplate the use of a mechanical device for removing the flesh from the fish.
There are a number of machines capable of achieving this, generally known as
'meat/bone separators'. These are able to separate the soft parts of the fish
(flesh, guts, nervous system etc.) from the harder parts (bones, scales, skin
etc.). The yield of flesh from a meat/bone separator is greater than that from
manual filleting and filleting machines since it will recover the flesh from the
head, belly flaps etc., which may not be included in a normal fillet. Indeed,
the carcases of fish after fillets have been removed will yield a significant
proportion of minced flesh if passed through a meat/bone separator.
It is feasible for whole ungutted fish to be passed through a
separator but the guts will also pass through the machine with the flesh,
producing a non-white mince containing gut contents, blood etc. In certain
cases, this sort of mince may be acceptable but often the fish need to be gutted
and washed before separation.
Uses of the mince
Having produced a mince by one means or another what sort of
products can be made? In many fish freezing operations where products such as
fish fingers, sticks, cakes, balls etc. are being produced, fish mince stripped
from the frames after filleting using a separator is incorporated into the final
product. This maximises yields, and the production of these types of fish
products is almost entirely confined to the developed countries of the world as
convenience-type foods. Apart from these conventional products, other uses of
minced fish, particularly from underutilised species, may be as additives to the
preparation of processed meat products.
In the context of developing countries, however, a major area of
interest is the use of minced fish for the production of low-cost salted and
dried products. This process may be particularly suitable for the utilisation of
shrimp by-catch and other waste fish. Salted fish is an integral part of the
diet in many developing countries. With traditional techniques, the salting
operation takes several days to complete and during the early stages there may
be insufficient salt to prevent spoilage. The need for a more efficient
technique to rapidly salt fish was recognised by Del Valle and co-workers who
developed a method in which minced fish was mixed with sufficient salt to
denature the proteins; the water thus released was pressed out and the pressed
cake was sun dried. The technique was designed for use in developing countries
and, as such, required little processing equipment. The process was subsequently
adopted by several other workers using a similar technique and more
sophisticated equipment, producing a blander product more akin to the taste of
the western countries. This was the subject of acceptability trials by the World
Food Programme in the tropics. This type of product has considerable potential
in the tropics if it can be made from more oily fish, the current products being
made from species of low fat content. In our own laboratories and overseas
programmes, we are attempting to develop a salted/dried fish product using
processing methods which could be applied at the village level in the tropics.
The work is concentrated on two main areas and two types of
product. Firstly, the production of salted minced fish cakes similar to those
produced by Del Valle but which do not require excessive pressure during
production and, secondly, the production of salted fish powders. It is important
that salt is evenly distributed through fish minces if they are to be adequately
preserved. When a mincer is being used to comminute fish flesh this can be
achieved simply by mincing the fish and salt together. This method has been used
successfully in the field to produce salted/ dried fish cakes from waste fish
resulting from commercial filleting operations. If other methods of comminution
are used, mixing of salt into the mince can be achieved by hand but there are
obvious advantages in the use of mechanical mincers. Addition of salt to minced
fish muscle releases some of the bound water. In order to reduce subsequent
drying times, as much of this water as possible should be expelled before
subjecting the material to drying either mechanically or in the sun. This can be
done by decanting, pressing or draining through cheesecloth. Once produced, the
salted and drained fish mince can be dried either in thin layers in trays or in
the form of cakes moulded using a hand-operated hamburger press. The drying
operation can be undertaken using a mechanical drier, a solar drier or by simple
sun drying. At the village level, simple sun drying would probably be the most
economical method provided that the climatic conditions are suitable. Many
tropical countries suffer periods of high rainfall and, during these periods,
sun drying would not be possible. A non-mechanical kiln of the Ivory Coast type
has been used during these periods in the tropics to produce a smoked/dried
product. It has been shown that the optimum concentration of salt for the
production of fish cake from raw fish is approximately 15 per cent. At salt
concentrations below 15 per cent, the water-holding capacity of the proteins in
the flesh is high and it is difficult to dry these minces. At higher salt
concentrations, the water-holding capacity of the mince is destroyed and,
therefore, it is easier to dry but, on the other hand, the gelling capacity of
the salt and protein in the muscle is destroyed and the mince will not form
cakes using a hand press. The main difference between fish of different salt
concentrations as far as the consumer is concerned is in the area of the
textural changes which occur. At salt concentrations below 15 per cent, a
cohesive mass of fish is produced and it is difficult to remove the salt from
the finished dried cake. With fish treated with higher concentrations of salt, a
spongy open-textured cake is formed from which the salt can be easily removed.
In practice, therefore, higher salted cakes have, after leaching of the water
prior to final cooking, lower salt concentrations than the salted mince fish
cakes that originally had lower salt concentrations (See Table 1).
Table 1 Salt content of salt/chambo
cakes before and after de-salting
Delicatessen products
Fish sausage
There are many sorts of sausage that can be produced using fish.
Most recipes are based on recipes for meat sausages where the meat portion is
replaced by fish.
Frying sausage
The ingredients for this sort of sausage include white fish
fillet meat, pork fat, rusk, water, salt, coriander, polyphosphates, pepper, and
dye if required. The fillets are chopped in a chopper until the flesh is finely
mashed. The other ingredients are added and the chopping is continued for 4 - 5
minutes. The mixture is then filled into edible sausage casings and then twisted
into sausages of the lengths required. The product resembles a normal frying
sausage in appearance and in taste; it is perishable and should be kept chilled
or frozen. The sausages must be cooked before being eaten: they can be fried,
grilled or cooked in the same way as meat sausages.
Slicing sausage
This product resembles a polony sausage. Although it is cooked
and ready to eat cold, it can if desired be fried. The ingredients are as
follows: skinless white fish fillets, pork fat, water, rusk, salt and pepper,
powdered cereal filler, and cayenne pepper. The fillets are chopped in a bowl
chopper until finely mashed, then the other ingredients are added to the bowl
and mixing continues for another 5 minutes. The sausages are then filled into
cellulose casings and tied off. The sausages are then heated for 2 hours in
water at 80 - 90°C. To prevent bursting, the water temperature must not
rise above 90°C. The sausages are then cooled in iced water for half an
hour. The product should be kept chilled or frozen but will keep for longer than
a year when frozen and stored at - 30°C.
A variation on the above recipe can be made inasmuch as the fish
sausage once prepared can be smoked to produce a smoked slicing sausage.
Frankfurter sausage
This product is similar to a frankfurter made with meat. It is
only partially cooked during the process and must be cooked by the consumer
before it is eaten. The ingredients for these sausages are similar to those for
slicing sausages but the proportions are different. Following production, the
sausages can be smoked for 3½ hours at 60°C in a mechanical kiln to
give them a smokey flavour. They are usually then skinned prior to sale. An
acceptable fish sausage can be produced using fish which have been smoked, such
as kippers. It is more usual, however, to use nonsmoked fish such as herring to
produce a normal sausage and then to hot-smoke the sausage to give it a kippery
taste.
Kamaboko
Kamaboko is a traditional Japanese fishery product which may be
likened to a meat loaf or a sausage without casing. It can be made in various
sizes and shapes. The first procedure in the manufacture of kamaboko is the
manufacture of a product known as surimi which is a paste or a dough. The prime
requirements for making surimi is that the minced fish meat must be elastic. In
the main, croakers, lizard fish and conga eel have the desired elasticity. White
croakers (Nibea argentata) are generally favoured because the kamaboko made from
this fish is highly elastic. The other raw materials, apart from fish, include
potato or wheat starch, salt, sugar, ajinomoto or monosodium glutamate, chopped
vegetables (carrot and burdock) and vegetable oils (if the product is fried).
The preparation of surimi is as follows:
1. The head, scales and viscera are removed.
2. The flesh is cut into single fillets.
3. The bones and skin are removed. This can be done either
manually or in a machine.
4. The meat is washed three times in drums of fresh water to
remove the fat. Different kinds of fish may be mixed with the main species at
this stage.
5. Excess water is removed either in a basket centrifuge or by
squeezing through a cloth.
6. The meat is kneaded in a machine for about 15 minutes.
7. Salt is added to the meat and the mixture kneaded for a
further 15 minutes; 20 - 40 9 of salt/kg are normally used.
8. Potato or wheat starch is added (100 - 250 g/kg of fish) and
the mixture kneaded for a further 15 minutes.
9. Sugar may be added at the rate of 30 - 100 g/kg of meat to
improve the flavour; monosodium glutamate is added and the mixture kneaded for a
further 20 - 30 minutes until it assumes a doughy consistency. Chopped
vegetables may be added if desired during the latter stages.
The resulting surimi is a stiff paste. The yield is around 40
per cent of the whole fish.
To produce kamaboko, the surimi must be shaped into half
cylinders or into the shape of bread loaves on wooden blocks. The loaves are cut
manually into pieces approximately 200 9 each and subjected to infra-red ray
treatment, or they may be roasted on the top to get a brown crust similar to
bread. They may then be dipped into dilute hydrogen peroxide to sterilise them.
The product is then steamed for 40 minutes at a temperature of about 80°C
and then cooled for 2 hours in the air. Packaging is in cellophane or
polyethylene which is heat sealed. The products can keep for about one week
during warm times of the year and up to two weeks in winter.
There are many variations on the basic kamaboko product, the
main ones being in size and shape. Hampen is square-shaped and chikuwa is like a
tube that is broiled instead of being steamed. There are also products such as
fish noodles which are by-products of the kamaboko plant since the process is
very similar except that the surimi is extruded through a vermicelli or
spaghetti machine (See the flow sheet).
Flow sheet for the manufacture of
kamaboko and allied products
Tuna ham
Fresh or frozen tuna, marlin, swordfish, whale meat, pork, salt,
spices, wheat or potato starch, and a natural casing are the main ingredients of
tuna ham which is produced in Japan. Tuna ham is really a smoked fish sausage
similar to salami but cut into thin slices.
The tuna, whale meat and pork are cooked at 86°C and
minced. The minced meats are mixed with the salt, sugar, starch and spices in a
mechanical mixer and kneaded well for about half an hour. The mixture is put
into large-size natural casings and smoked over smouldering oak chips for about
12 hours. The smoked ham is then cut by machine into thin slices and vacuum
packed in polyethylene-cellophane bags. The ham will keep for about 10 - 14 days
at room temperature.
Fish balls
In China, low price fish such as sharks and lizard fish are used
to produce fish balls. The meat is removed from the skin and bone and ground to
a paste with water added. Ingredients such as starch, sugar, flavour essence,
salt, water and spices are added and the balls are formed either by hand or by
machine. Once formed they are put into cold water for a short time and then
cooked for 15 minutes in boiling water.
Fish crisps
Fish crisps, shrimp crackers or krupuk in Indonesia are produced
in considerable amounts. The product is also available in Thailand where it is
made from fish. In Indonesia, the product is known as krupuk udang or shrimp
krupuk. The krupuk industry is concentrated in East Java.
Shrimp or fish are used but the product made from white shrimp
is more popular and higher priced than the others. The fish material should be
absolutely fresh. Tapioca flour, sugar and salt are required. Eggs may also be
added. To produce 100 kg of krupuk the following amounts of raw materials are
required:
The fish or shrimp are mixed with tapioca flour in various
proportions depending on the quality of the product desired. The best quality
contains at least as much shrimp as tapioca. Lower grade products may contain
much less shrimp and may be as low as one part of shrimp to ten of tapioca. The
mixture of shrimp meat and tapioca is either pounded with wooden poles in a
stone mortar for 1 - 2 hours or mixed mechanically. Machine mixing is not
favoured in Indonesia as the product develops a slightly darker colour. During
pounding or mixing of the shrimp meat and tapioca, the other materials such as
sugar, salt and eggs are also added and mixing continues after addition of
water. When mixing is complete the material forms a paste. This paste or dough
is put into metal moulds in the shape of half cylinders; the filled moulds are
placed in racks in a boiler containing some water. The moulds are exposed to
steam but not immersed in the water. The steam gelatinises the starch and
coagulates the proteins of the shrimp meat. Steaming continues for about 3
hours. After steaming the moulds are separated and the blocks of cooked
fish/tapioca dough are allowed to cool for 2 - 4 hours. When cooled, they may be
sliced in a machine to a thickness of 4 - 7 mm. The slices are then dried in the
sun. The product is packed in paper cartons of different sizes depending on
consumer requirements.
Krupuk is fried in oil before being eaten. This makes it expand
several times and it is used as a side dish in Indonesian, Chinese and Thai
cookery.
1. SUBBA RAO, G. N. (1961) Fisheries Products Manual. Food and
Agriculture Organization of the United Nations, Rome (FAO). Indo-Pacific
Fisheries Council.
2. TORRY RESEARCH STATION (1970) Torry Advisory Note No. 43,
Torry Research Station,
Aberdeen.
