Preservative of Fish
and Pran Jyoti Sharma2
Division, Central Institute of Fisheries Education, Versova,
of Fisheries, AAU, Raha, Nagaon, Assam-782103
of corresponding author: firstname.lastname@example.org
is one of the oldest methods of fish preservation developed in
prehistoric period. In recent times smoking is used as a method of
preservation with the incorporation of smoke flavour and development
of colour. In under developed countries this method is used as a
means of preservation only, while in developed countries this method
is used to impart smoke flavour to the product since in these
countries there are other sophisticated means of preservation of
fish. Smoking is a method of preservation effected by the combination
of drying, deposition of naturally produced chemicals resulting from
thermal breakdown of wood and salting. All these three factors help
in preservation of fish. Smoked fish is ready to eat and has great
demand in western sophisticated markets. Smoking is also used as an
intermediatory step in the preservation of canned smoked fish. Here
before canning, fish is smoked to impart smoky flavour. Smoke is a
good preservative since it contains bacteriocidal and antioxidant
properties. Around 2% of the total world catch is used for preparing
smoked fish all over the world. In India, "masmine" is prepared
in Lakshadweep group of islands.
types of smoking
In this type, the temperature should be maintained above 30oc
and the normal range is 70-80oc.
In hot smoking fish is completely cooked and consumer can take it
without further cooking.
In cold smoking temperature should be maintained below 30oc.
Here meat will not be cooked and it is used to impart flavour in the
meat. So it has to be cooked before consumption. This method is
followed in temperate countries as temperature in these countries is
method of hot and cold smoking:
Here fish is first smoked below 30oc
for few hours and finally it is hot smoked.
Liquid smoking extract is prepared by dry distillation of wood and
then it is concentrated to a particular degree and later it is used
in proper dilution. Dilute smoke is concentrated, fishes are dipped
into it for required time and then it is dried.
smoked particles are charged into an electrical field (usually
positively charged) and at the same time fishes are negatively
charged. The positively charged smoke particles are attached by the
fish. It is a rapid process.
of wood used for smoking
is prepared by "smouldering fibre" ie. burning without flame. The
source of producing smoke is the wood. All types of wood are not
suitable for smoking purpose. Depending on types of wood odour and
taste differs. For smoking hard wood is suitable and we should not
use soft wood. Types of wood used for smoking are mentioned below.
shell and husk
wood ships (leaves)
consists of two parts: combustible and non combustible. The main
combustible substances are divided into three parts- polyoses,
lignins and to some extent resins. Polyoses contain cellulose and
hemicelluloses. Polyoses and lignins are the main components of hard
wood, but in soft wood resins are more common eg. turpentine. In hard
wood, polyoses comprise 2/3 rd and lignin comprise 1/3 rd of the
wood. Freshly cut wood contains 40-60% moisture which is not suitable
for smoking. A good wood containing <25% moisture is preferred for
smoking. If the moisture is more than 25% then it is considered as
damp wood. When wood is burnt it gives compound mixture of chemicals
in addition to main gas like CO2
and traces of H2O
and CO. When wood is burnt polyose part gives out aliphatic chemicals
and when temperature reaches 280oc,
the released chemicals are alcohol, aldehyde, ketone and acids.
Lignin part is resistant to heat and when temperature reaches 350oc,
they will burn and give out phenolic compounds.
properties of smoke
is due to combined effect of heating, drying, salting and also
deposition of chemical constituents of fish. Chemical constituents
like formaldehyde and acetic acid are found to show bacteriocidal
effect, can prevent fungal growth and can inhibit viral activities.
Deposition of smoke is more on the surface and hence smoke is more
effective against bacteria on the surface than on the inner portion
properties of smoke
also has antioxidant properties and it is mainly due to the presence
of three important chemicals namely 2,6-dimethoxyphenol,
2,6-dimethoxy-4-methylphenol and 2,6-dimethoxy-4-ethylphenol.
has carcinogenic property due to the presence of 3,4-benzopyrene. It
is a polynuclear aromatic hydrocarbon and its formula is C20H10.
Depending on the method of smoking the amount of carcinogenic
compound in smoke varies. To prevent the carcinogenic compound,
electrostatic precipitation is used through which smoke is allowed to
pass. The electrostatic precipitation can absorb the carcinogenic
compound and we can get pure smoke.
of relative humidity in smoking
vapours are usually absorbed quickly by moist surface than dry
surface. Moist surface can absorb 20 times more than the dry surface.
So before smoking we should see that there is a relative humidity of
60% and it is optimum for absorption of smoke.
formation in smoked fish
colour of the smoked fish is due to the deposition and subsequent
oxidation of phenol. In recent times fish curers use dyers for
colouring of smoked fish in a uniform way. Colours are not permitted
in some countries like UK, whereas in countries like USA it is
permitted. From vegetable source colours may also be used in smoked
fish to enhance the appearance of the product.
Today there are two
main methods of smoking fish: the traditional method and the
mechanical method. The traditional method involves the fish being
suspended in smokehouses over slowly smouldering wood shavings. The
fish are left overnight to be naturally infused with smoke. In the
mechanical method smoke is generated through the use of smoke
condensates, which are created by the industrial process of turning
smoke into a solid or liquid form. The flow of smoke in the
mechanical kiln is computer controlled and the fish generally spend
less time being smoked than in a traditional kiln.
fish is one of the best ways to preserve fish. Smoked salmon and
smoked mackerel are two of the top purchased smoked fish items in the
world. Salmon, mackerel and herring are universally available
both as hot-smoked and cold-smoked, while other fishes are
traditionally preserved by anyone of the smoking methods.
J.R., 1988. Fish
smoking and drying,
Elsevier Applied Science, ISBN 9781851662470.
Y. H. et
Science and Applications.
New York: Marcel Dekker. ISBN 9780824705480.
(2004). "Wood Smoke and Charred Wood". On
Food and Cooking
(Revised ed.). Scribner. pp. 448–450. ISBN 0-684-80001-2.
Seafood — Fish — Crustacea
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