46 Fish Preservation

Preservatjon of fishes is A Very important part of present on the body. plls and gut of the fish fnt
commecial fisheries It is done in such a manner
good medium for development due to hih
hat the fishes remain fresh for a long time, with moisture (75805) contents in the fish lesh More
loss of laste, odour, flavour, nutritive bacteria are further added during handling and
Value an4 he
perishableah. Fishcs are storage in unclean places Fishes get cut
quickly
abrasions etc, during catching operations leafing
o properly preserved. Dunine to hacmorhage These peovide
quantitics of fsh are caught and require proper
preservation so as to be available during lean cvonment for bacterial activity which e mat
period After preservation, d
e e e i n s in the fish fesh
bcs can be
transported 1o long distances for consumption In olytic micrabes sach as
Pseudomonar. Pate
India, with its uopical and subropical climate, the
Halobocterium,
Chromobacterun
Micrococcus.
pooicn tnore acute, as heat and moisture
Carbohydrstes present in small amount in he
hes may lesh ae degraded by
oruinarily remain feh
5 hour
carbohvdrag fermmencine
microbes Like
and begin to decompose rapidly after huL Sireptucoccas Leuconesoc
Micrococus clc Fat contents of the fah fesh
Reasons for Spoilage of Fisbes decompesed by elatively few gram
negative
Pish spoilage occurs chietly due to three
acting mentioned
gradation occur though the processes
belgw

Prcn PeeslyE cnes

cion, and
O) Chemical
1 Fiah Catees
spailage due to miceoblal action
Mcrobal action involves chiefly bacterial spoilage
the fiah lesh A large mumber of baceria
In Fish spoilage due to enzymaGe action () Cleaning.
laree anount of enrvmes,
fish lesh whic
is spoiled by 2) Degutting and
Qule
3) Conervation and storage
be ca after death of dhe fahes and sohee e
even
L Cleaning It is done by cold ceaa water
R hy auolvsis and make the fish suscepible so to remove microbes like bacteria and sme, biocd
ri inlection Proteinae for example, can stains, mucus, faeces, sand and mud etc fom the
dgest nuscle proteins of the fah, catalase, the body sarface of fah.
l snoilage and ATPare bring about complete 1 Deguttimg Cleanod larger Aihes are
emoval of ATP from muscle tissue in 6-8 hours degutted ie all the internal organs or viscera are
Autolysis of proteins renults in formation of removed and the bady cavity i wasbed. l i
requircd to prevent microbial decompositios and
anino acids and other nittogenous peoduct which
ipon furher decomposition release NH, CO. enzymic autolysis respectively.
volatile basic compounds vi. mines and fowt 3 Conservation und storsge. Coiervabion is
smelling products viz, indole, skatole, etc. essential for keeping the dead fabes in fresh
condition for quite a long duration. It is achieved
(u) Fish spoilage due to chemical action by employing any one of the following mctbods
Spoilage of fish fesh due o chemical action is
the least important, as it occurs in fatty acids only. Retrigeration
tis more pronounced in faity fishes like sardines, The recent method of preservation is refrigeration
ackerela rout. catla, grass carp, ete whach as a as i prevents putrefactioa and decay. Frozea
fishes retain their utritive qualities for long
sh Besh time. perhaps even for a year. Fishes are packed
in ice layerns for short-time preservation in mackets
viscosity also changes, Rancidity may be prevented or for trinsport Fur long-time peservation, large
by te use of antioxidaats like polyphenol or ther clectric rofrigerators or deep freeze cabinets e
iicous luid and minimizing exposure of fish to employed. In big commercial concems like those
moist atmospheric air. in he Sasoon Docks in Mumbai rooms e
cooled by electric refrigerating mcthods and large
Methods of Fish Preservation quantities of fishes are storod in them for months
The most important principle of preservation of Quick frezing is advised whert fishes have to be
Eshes is cleanliness and sanitation. Preservation kepe for a longer period The camer air-plast type
can be doc, bodh for short and ong duraion by of quick freezing is employed at Munba.
Mangalore, Calicut, Cochin and Trvendrum
employing methods given below.
Lowering of the lemperature ta ahout oc
Sbort duration preservation
(Chilling) is he most efective method of
Whea prservation is tequired for short duration preventing putrefactioa and extending the life of
(24 days), he captured fishes e kept in crushed the dead fshes. For chilling large amount of ioe
ice and traasportod to the market for their sale Ia is used to lower the temperature of the fish. Large
ice, the range of semperature is from 0-4C, which fishing vessels a providcd with uch acilities
rtards the microbial action as well as autolytic Alternate layers of lce and fish must be aranged
cRrymic activities are also checked 1o bring down the temperture of the flesh ao
about 0'C Ia the large fishes, lce must be applicd
Long duration preservation the abdominal cavity aftet guting Aatibicics
Whea the preservation is needed fora long period ike Trmmycin Aureomycin can be
ime, he caught fishes at passed thrnugh the hb he microbial
following Heps icoh
growth Chilling does not alter he physical state
 Fith Preservaion
456

of the fishes and keep them in palastable state for reated with salt (NaCi) solution. Salt dehydrates
body
entcrs their
the killed fishes by osmosis and
a few days Howevet, this nethod is o0t suitable, ncentration io the saturation
issues 1o increase
when the intention to keep fishes for a period of e of uall above 25% stops
more than two wecks point. A concentration kills
further muluplicaiton of microbes and even
() Deep freezing them, specially the halophobic microbes However,
halophilic, remain
For deep freeting. captured Ashes ae cleaned, few strains of bacteria like of the
gutted, sorted and trimmed to suitable sizes. They unaffected causing pink or dun spoilage
are frozen cither immediately with in 30 minutes fshes Normally, 20 kg of pure salt is required for
of their catch (quick freezing) or within a period cach 100 ke of fishes. It is found that only oily
extending from 3 to 72 hours (slow freezing) The isbes require more salts.
freezing is achieved in ice, mixed with salt Methods of salting Three methods of salting
Addition of salt brings the enperature gradually have been evolved
down from1C to- 18C. By deep freezing () Dry salting.
fishes may be preserved for a very long period (2) Wet or brine salting. and
Preservation by deeo freezing often causes loss of (3) Cold salting
slight damage lo issuCs, Sometimes, fishes are
(a) Dry salting. In this method,powder
Tlavo and
he fish becom ineless This may be prevented first cleaned, and rubbed with salt
salt
in wax paper or cellophang
by wrapping the fisbes fish. ihen packed in tubs or in cementcd tanks. Dry
Caai orescrves the powder is sprinkled in betwecn layers, as he
and by giazing he t
colour and lavour the fshes It should be fhes ae arranged in the container (Fig 1), The
emphasizd hat deep froen fishes should be tio of salt 10 fsh varies from
ratio 3o 1
immedaalcly uscd afier hawinse cacause surviving on local practice, weather conditions
depeading
microbes begin to multiply rapidly s soon as and typc of
fish. After 2-3 days, the fishes are
frozen ish is warned removed from he tubs or container and dricd in
for 2-3 days. Dry salt practice in pits for
[un Freeze-drying
hsh preservation is donc along he east coast of
It is A complecalod process and requires in Andhra Pradesh. Such preserved
considerable establishrnent. As it is a cotly and of inferior quality but find good market
laborious process, only the best fishes are trealcd. among the poor classes
The fisbhes are first frozen and then dricd by
ublimation it., he ice is converted into waler (b) Wet or brine saltng. Wet-salting
vapour without melting into water. The iavour, mostly practised on he Koakan coast. Cleaned
colout and autritie value of the fish remains fully fshes are packed in large containers having
concentrated salt solution (203o) ano
eserved. The fh is irst cooked, if it meant fo
immediate consumnpion, after opening the packet
daily ill property pickled Large-sizcd fishes
the todian salmon, sccrfishes and black Pommfrets
or tin The fialh is frozen to-20C by placing it in
a freczing chamber. Fish trays are then transferred ace guttcd fist and inside is cleaned. Also.
to chanber containing horizontal heating plates longitudinal slits are made in the flesh to allow
for dryying in a vacuum. Tbe died fish is packed penetration of salt Salt is applicd in the following
or canned in ait conditiuned room saccessive stages. On the first day, half of the
is rubbed into the incisions and the fishes
(IV) Salting stored on the cemented floor of the curing yard
Salting is a forn of pickling and is a very old and On the second day, the fishes are shuffled so
common nethod of preserving fish in lndia and bring the bottom layer on top and alf
also theoughout the world in saling. tie ishes are remainng salt is rubbed and the fshes are
 [457
Fash Preservation

Clean fish

Re 2. Snoke houre

Fg L Sated fishes1 contE out from the salt solution and are suspended on
rods in snoke house. Smoke house (Fig. 2) is
restocked The stock is left undisturbed for 7-10 merely a shed or a box over a fre, which is
davs The salty water that oozes out from the controlled so that it produces smoke instead of
fishes is llowed to drain off Wet salted fishes flames The fishcs are merely hung inside the
may be sold without drying It does not keep good smoke house (from head to tail), so that they are
for long and. therefore, has to be used wihin surrounded by smoke. It takes about six hours to
3-4 months smoke fishes so that they can be eaten or stored.
(c) Cold salting. This is done by spreading Smoked fish does not last as long as salted
powdered salt and crushed ice on the fish. About fish, because it must be refrigerated, frozen or
22-26 lb of powdered salt per 10 kg of fsh is canned, if it is to be stored.
usually recommended After salting. the Smoking removes additional moisture and
conservation is done in cold rooms, having a increases the flavour of the fish flesh. Smoke has
its
iemperature range of 2-3C. a preservative effect, which is ascribed to
How to use salted fish. Before use, salted phenolic constituents
fish should be soaked in freshwater overnight. [VI] Drying
Change of the water atlcast once during this time The object of drying is to remove moisture
is roquired. The soaking removes he salt. The
Jonger the fish is soaked, the more salt is (debydration) from fish tissues This heips to arrest
bacterial and enzymic putrefaction. When moisture
removed After the fish has been soaked, it can be
used in any way like fresh fish.
contents reduce upto 10-20%, the fishes are saved
from being spoiled, provided they are storcd in
(V] Smoking dry conditions. Sun drying is the most ancient
method. In India, over 35% of the total catch of
Smoked fish is not as popular in India, as it is in sea is cured in the sun
Western countries like Norway and Sweden Small marine fishes, such as ribbon fish,
because the peculiar smoky lavour is not relished
by Indian fish eaters However, small quantities of silverbellies and Mumbai ducks, are spread on the
surplus fiahes are smoked in Chennaa and Orissa open sandy beach Sometimes, mats made of cor
Sardincs, mackerels, seerfish, pomfret,. jew fish and or palm leaves are used for spreading the fishes
hilsa, are considered good varieties for smoking Oflen, fishes like Mumbai ducks are hung on
Fishes are first cleancd and gutted and then bamboo or wooden rods or on ropes stretched
horizontally between poles (Fig 3), Large and
soaked into salt solution or brine. They are taken
 458 J Fse Preievation

the west coast of India lke Calicut, Gas and

aCanning involves packing of fishes in
boxes to preserve them fora long time
ning is
Cannine
complcateo process and costly
y o tecnnica ckperise is equired
Hene he canning produc oyY The
shes
which sre sealed airtight and sterilized by beat
Pasting pickling and spicin
methods of the easL The fishes are
are cu
cut into slice
salted and dried.
The fishes used for canning are gutted out
R&yg det i had and cut into pieces of suitable size. Their bead,
tail. fins and viscera are removed and the picces
mediumsind fahes are usually gutte and salted are dipped in brine to remove blood et.. from the
before dring tissues. Pieces re now immersed in hotwater or
Fih dying can be achicved eiher naturally exposed to the steam to remove adhering materials
r by aificial means which could not be removed by cleaning with cold
Nataral drying. In natural dying the caught water. Pieces are salted and dried.
fiahes are cleaned and dried in the sun shine, so They are hea mixed with a spicy paste
caliod sun-drying is actually not the ideal way ground by mixing vineger, red chillies, mustard.
of preservatin has cetain disadvantages. Iis gartic, turmeric and tamarind in oil medium. For
ot hygienic s slow and resulas in much loss pickling. usually mackerel and ardines are used.
drough puitaction and spoilage und the dried Finally the processed pieces are sealed in
fi develaps a peculiar odour. can be camied containers, preferably tin boxes or jars The sealed
o only in dy.well scrated climate receiving containers e again subjected to heat treatment to
sunahine. which is not too hot. . thus depends kill completely the microbes left in he flesh of
upoe de nvientalt factors and availability of cut pieces of fishes Containern are tested before
space So much , only the shin fishes can be their transpartation to the market.
peoserved by s metod. because the fat shes Processing Fish processing includes all the
processes discussed above as cleaning. freezing.
have much feh allowing microbial decomposition
o continuc in decper parts of heir body drying. salling. canning etc. Fishes may also be
Anificial drying, la tifical drying. he processed into edible meals and oils (that are
killed fshes are cleaned guted and decapitatcd. aca oye products of the fish industry,
They are hen cut lengthwise to remove large parts Chapier 44) Fiah meal is preparod
disced
of eir spinal colunn followed by washing and rom body parD o the fish as fins, gills,
drying them mechanicaly This process yildaa u b y processing. Majot pan of the hah
high quality product which retains he natural fom, but there in salted
flavour and murve values G k o Varoas
ye- products of the
VI) Canning
Demerits of fsh preservation. Although the
This proces of fsh preservation wat initally preservation and processing constitutea
evalved in Eurup and sow intoduced in other important aspect of the fah industry, it has certain
counuries including ladia tains the natural
drawbacks well, particulatty with respect to
favour of he fish Whenevc avalable in lurye retaining quality of fish flesh The demerits are
quanities, sdines and mackerel1 ae canned on described here briefly in the following points
Fuh Preseration 459

0) f proper hygienic measures are not adopted mechanical damage to the muscles Cell
the processes like cleaning. gutting membranes burst, suuctures get deformed
und evisceration etc.. more harm would be and the fish flesh loses much of its flavour,
resulting to the preserved imaterial owing to and taste. The flcsh becomes dehydrated and
increase in the microbial population loses its exture toa
a) Poor or incomplete preservation leads to (5) Excess salting allows growth and
decarboxylation of flesh amino acid i. multiplication of salt tolerent bacteria
histidine 1o histamine The histamine and causing 'Pnk eye' spolage of fsh fesh
few other related substances collectively (6) Salting combined with smoking resuls in
named saurine, ae he common causes of loss of protein (about 1-5% due to salting
fish food poisoning and &30% due to smoking)
0) Dryng reduces weight nutritive value and 7) Smoking also promotes rancidity of fat
contents of lesh and hence dimin,ahes
he dicabily of the hh hesh. of the fish
(4)
Besh is hecause of the ice crvstals (8) ch loss f vitamin B
formed during chiling and causing pantothenic acid, and ascarbic acid.

IMPORTANT QUESTIONS
We sn esay on fih peervis dprocessing
Ge he aos or polage o fishes Decribe the methods af fih pesenaion
ng d prervat ti) e t g e (iv) Derp
Mang vi) Smking (viit) Dyjag ia) Caaning a) Deerta of fh pmenation