The preservation of freshness in fish (commonly referred to as fish handling) and the conversion of fresh fish into other products can both be considered as methods of processing. In commercial practice, however, the term "processing" is confined to the conversion of fresh fish into other products

Gunasekera, C.

Aquatic Commons

rfhe Processing of Fish and other Marine 
Resources 
By 
0. GuNASEKERA 
(Ceylon Fisheries Corporation, Colombo) 
(A) Fresh Fish 
'~he preservation . of frm;hness in fish (commonly referred to as fish handling) and the 
convm·swn of fresh fish mto other products can both be considered as methods of processing. In 
commercial practice, however, the term " processing " is confined to the conversion of fresh 
fish into other products. Let us first consider the preservation of freshness in fish. 
Deterioration in the quality of fresh fish is due firstly to enzymatic action ·within the 
tissues of the fish which causes autolysis or self-dissolution. Enzyrnes in a living fish assist 
both the building-up as well as the breaking-down reactions of normal Inetabolism. After death, 
bt11lding-up reactions cease but breaking-down reactions continue, finally breaking down the 
tissues. Secondly, deterioration is due to bacterial action. The tissues of a healthy living fish 
are sterile while the surfaces in contact with the environment are contaminated with bacteria. 
\Vhile the fish is alive, the bacteria are continuously removed by the flow of slin:1e, lTlovement 
of water through the gills and the passage of food along the alimentary tract. On death, all 
movement ceases, the bacteria stagnate and multiply on skin, gills and intestines and then 
penetrate the flesh using arteries and veins as roadways. Finally, the presence or absence of 
oxygen (air) influences the course of certain reactions, the growth of certain bacteria and the 
rancidity of oils in the :fish. · 
The first step in reducing the rate of deterioration is by cleaning (called dressing) the 
:fish. 'rhis involves washing off slime, removing gills and intestines which also contain bacteria, 
1·ernoving easily decon1.posable material such as blood, roe and fat layers and separating out 
stable, edible portions such as fillets. In the case of small fish, it is uneconomic to dress each 
individual :fish so they are merely washed in bulk; in addition, if the cleaning process takes a 
long time and the fish are not cooled, they can deteriorate clue to exposure to high room 
temperatmes. Therefore, dressing fish is applicable only when it can be clone quickly, i.e., 
when fish are large and there are sufficient workmen. 
After dressing, the next stage is to cool the fish as the rate of all reactions (enzymatic 
and bacterial) are reduced by cooling. 'When ice is used, fish can be cooled to just above 32 oF 
(OCC) but the water (juices) in the fish will not freeze as it does so only at 28oF (-2°0): ?torage 
time on ice is counted in days, usually 8-12. 'rhere ttre no flavour changes due to wmg but 
flavour changes will take place clue to slmv deterioration with time. :B'ish without ice will 
deteriorate much faster as they are at a higher temperature. 
Frozen fish has been cooled below its freezing point (28oF) and so the water inside the fish 
is in the form of ice. Freezing is done by a blast of cold air or by contact with a cold surface 
which brings clown the temperature rapidly. Rapid freezing is necessary to prevent fractional 
crystallisation and the formation of new combinations among dissolved constituents vvhich 
ca~1ses flavour changes ancl to prevent the formation of large crystals ·whose expansion while 
freezing may break down cell walls ancl cause oozing or chip on thawing. Frozen fish are stored 
at low temperatures (-5°F to -lOaF) (-20o to -23°0) and keep in good condition for montlB or 
even years. 
92 
Quality in a :fish continuously deteriorates from time of death. All preservative method::; 
merely slow down these changes and are not able to stop them completely still less to teverse 
them. The point at which the :fish is to be judged as un:fit for consumption is very arbitrary and 
is related to n1.arket conditions and consumer acceptance. This judgrnent. is independent of 
bacteriological tests for suspected infection. Fish found contam.inated with disease-causing 
bacteria must be condemned as un:fit irrespective of the state or quality of the :fish. 
Laboratory tests for quality (chemical or physical) are unsatisfactory as they deduce 
quality by evaluating a single component and the tests become even more unreliable when 
applied to catches in tropical waters which usually consist of nun1.erous varieties of fish in 
different stages of maturity. Therefore, testing for quality is best done by human judges who 
test many aspects of the fish (appearance, touch, smell, etc.) and also know t.he quality 
acceptable to the local market. 
'I'he following conditions mnst be satisfied for ±ish to be sold in the fresh form: 
(i) they must be of varieties acceptable to the market; 
(ii) they must be '.vhole or filleted and not erushed or in scraps; 
(iii) they must be maintained iced or frozen to preserve their quality. 
It is, therefore, seen that there are specific conditions to satisfy before fish can be sold 
in the fresh form. This makes it neeessary to convert :fish which eannot be sold fresh into other 
prod.uc·bs. The necessity for conversion arises through the follmving circumstances:-
(a) lack of faeilities for handling fresh :fish; 
(b) fresh fish in excess of facilities available £01' handling in the fresh state; 
(c) large quantities of a particular variety all of which cannot be sold fresh; 
(cZ) crushed or damaged fish 1vhich have lost their market appeal: 
(e) inferior varieties of fish which have lim.ited or no sale in the fresh form; 
(f) unused portions after cleaning or trimming; 
(g) portions of special value such as fish livers which can be processed for oil. 
( 1;:) ) Processed Fish 
.Processing makes possible the full use of a resource. It does not enhance quality for a 
deteriorated product cannot be improved. However, it may change an unpalatable product to 
a more palatable one or extract an usable product frorn discards. Processing often concentrates 
the food value of a product. For example, dried fish has 40-50% protein compared to about 
20% for fresh fish. Extracted fish liver oil is a more concentrated and stable form of Vitamin A 
than the entire Ever or the entire fish. Processed fish is more stable and easier to handle than 
fre2.h fish. rrhe value of a resource is greatly increased by extending its distribution. Processing 
of ±ish makes it easier to distribute this resomce throughout the population and also easier to 
export to other countries. 
(1) PFochwts similar to fresh fish.-In canning, fish and flavouring ingredients are sealed 
in a tin and the tin is heated to a temperature at which the cont.ent.s are cooked and sterilisecl. 
Clanning is an useful method of dealing with inferior varieties of fish 01' those caught in largt' 
qmmtities. Canned fish replace fresh fish at table and do not need special faeilities for transport 
or storage. However, the initial cost is high due to the cost of the can and the cooking process. 
Fish sticks and fish cutlets are made of ground fish ftesh and pastry, and so make use 
of inferior varieties and trimmings. They are to be regarded as a form of fresh fish and need 
icing or freezing for storage. 
Fish can be dried by the dehydrating action of salt or by heat. Dried fish does not need 
to be iced or frozen and, being about half the weight of fresh fish, can be transported at less 
cost. ·when the fish are unfermented, they can be substituted for fresh fish when cookec1. 
\]3 
Unfortunately, fennentative flavours develop readily and, in Ceylon, have become an accepted 
dwracteristic of dried fish. :Fermentation adds pungent flavours and changes the fish from~ a 
food product towards a condiment. 
(2) Products of the condiment type .-These products are highly flavoured and so can be 
used only in lin'lited amounts, more as a condiment H'lan a food. Local dried fish (karavala) 
through lack of control in processing, develops inadvertent fermentation flavours. However, in 
the preparation of pickled fish (jarcli) fermentation flavoms are deliberately sought and 
encouraged by adding flavouring ingredients such as goraka, tamarind and vinegar and using 
barrel;,: of particular vvoods for curing. 
Smoking is another method of adding flavom. Lightly smoked, lightly dried fish can be 
used in the same way as fresh fish, but heavily smoked, hard dried fish will be of the condiment. 
type, chief of ~which is maldive fish which is fish which has been boiled, smoked and har(1 
dried. 
Another product, fish sauce, is a fully fermented fish product ~which yields a.n aromatic 
liquid to be used as a sauce. 
Any variety of fish can be made into karavala, jarcli, maldive fish or sauce, each variety 
loncling its own flavour to the product. All these processes reduce the weight of the fish. 
Conversion of 10 lb. of fresh fish to karavala or jardi will yield about 4 lb. (varying from 
;-) to 8); conversion to sauce will give 3-4 lb. liquid, while you can prepare only 2 lb. of maldive 
fish from 10 lb. of fresh fish. It is, therefore, uneconomic to process any fish that can be solcl 
fresh. 
(C) Special Products 
(1). Fish. M eaZ .. -Fish is boiled, ~1ehydrat~d, defatted and ground up to yield about 
one-fifth 1ts wmght of coarse powder of h1gh protem content (40-70%) to be used for animal food. 
If well prepared in special apparatus, the material can be used for human consumption as an 
additive to flour from grain. Local conversion into animal meal is clone ~with crushed fish, unsold 
fish ani! varieties unpopular eit.her in fresh or dried form. 
(2) Fish Liver Oil.-Livers of fish are chopped up and steamed in the absence of air to 
give a vitamin-rich oil. This oil is locally produced mainly from shark, but livers from other big 
fi.sh are :=>Jso used in the extraction process. Fish liver oils vary in their vitamin content and 
are blended with a vegetable oil (e.g. groundnut oil) to produce a mixed oil of standard 
Vitamin A content. Standardisation is necessary to recommend a fixed dosage and the blending 
makes the oil more palatable. 
(3) Auar.--This can be obtained frorn reel seaweeds (Grac£l((,ria. spp.) 1vhich are 
commercially abundant off Trincomalee where they occur in depths upbo 4 fathoms. These 
seaweeds Rre collected during July to October and about 100 tons per season are exported to 
J a1-;an by private traders. The possibility of manufacturing crude or purified agar in Ceylon is 
under consideration. Agar forms a jelly which is populm· as a sweetmeat m:td \Yhich has technical 
ns0s in bacteriology and medicine. 
(4) Alr;in1:c Ac£cl.-This can be obtained from brown :::eaweeds ~Sa.rgas.su·m spp.) which 
a1·o commerci:=tlly abundant off the S.outh-vVest coa.st (from Beruwela to H:=tmbantot:=t). In this 
region the beds extend upto 400 metres from the shore and are estimated to be able to yield 
about 130 tons per season (October to January). These weeds are not exploited so far as brown 
seaweeds are of world-wide distribution (unlike the tropical reels) and there does not appear to 
be an export market for them. Alginic acid is an emulsifying agent with a wide variety of uses 
in food products (ice cream, cordials, etc.) and technical industries such as textiles and paper. 
(5) Other 1\II arine Products .-These include pearl oysters (for pearls); chanks (for shells): 
window pane oysters (for pearls and shell material); beche de mer (boiled and dried holothuri:=t 
for food); shark fins ( cartila.ginous rays used in soups).: isinglass (gelatinous extract from fish 
air-bladders); fish oil (separated in preparation of :fish meal) and stearin (separated out Jron'l 
liver oils and used for water proofing boats, etc.). 
94-
BIBLIOGRAPHY 
1. Preparation 'of Maldive Fish (Description of Methods used.) 
ANON. 1961 
DERANIYAGALA, P. E. P. 1933 
HoRNELL, J. 1950 
JoNES, S. & KuMARAN, M. 1959 
MgPAS, A. H. 1927 
Maldive Fish. I. P. F. C. Fisheries Proclttcts Manual, pp. 160-161. 
Cured Marine Products of Ceylon. Cey. J. of Sc. Sect. C., Vol. 5, 
pp. 57-58. 
Fishing in ~Many Watel's. Chapter 7 (pp. 65-69) Bonito fishing in the 
Maldive Islands. Can>bridge Univ. Press, 210 pp. 36 plates, 44 figs. 
The Fishing Industry of Minicoy Island with special reference to 
the Tuna Fishery. Ind. J. of Fish. Vol. 6, No. 1, pp. 30-57. 
Administration Report of the Govt. Marine Biologist for 1926. Sect 
VII Misc. p. F 12. 
2. Preparation of Beche-de-mer (Description of Methods used.) 
DEitANIYAGALA, P. E. P. 1933 
HORNELL, JAMES. 1917 
Cured Marine Products of Ceylon. Cey. J. of Sc. Sect. C., Vol. 5, 
pp. 68-70. 
The Indian Beche-de-Mer Industry : Its History and Recent Revival. 
_Nladms Fish. Bulletin Vol. 11, (Hept. 4) pp. 119-150. 
3. Processing (General) (Ceylon References) 
ANoN. 1958 A Guide to the Fisheries of Ceylon. Bull. Fish Res. Stn. Ceylon 
No. 8; 72 pp. (An informat,ive outline of the fishing industry in Ceylon 
covering resources, fishing methods, utilization of catch and the 
administrative and technical assistance provided by the Govt. of 
Ceylon.) 
ANON. 1961 The Ceylon Lobster. Ceylon 'l'oclay, Dec. 1961 pp. 10-11. (Methods 
of trapping lobsters and freezing them for export.) 
DERANIYAGALA, P. E. P. 1933 Cured Marine Products of Ceylon. Cey. J. of Sc. Sect. C., Vol. 5, pp. 
49-78. (A historical and descriptive account of the processing of 
all types of marine products with details of materials and methods 
used and with particulars of various curing stations round the coast 
of Ceylon.) 
DE SILVA, N. N. & LANTZ, A. W. 1956 An investigation into the use of Sctlvinict for the preservation of fish 
during storage and transport. Frog. Rpt. Fish. Res. Stn. Ceylon 
No.2, pp. 51-53. (The practice of packing fish in Salvinia plant leaves 
is shown to have no specific advantages but instead may produce 
undesirable effects.) 
DE SILVA, N. N. & ME-NDIS, A. H. ViT. 1963 Survival of Staphylococci on frozen fish. Bttll. Ft'sh. Res. Stn. Ceylon, 
Vol. 16, No. 2, pp. ll-18. (The behaviour of test cultures on fish 
frozen and stored under varying conditions.) 
DE Sn.vA, N. N. & Mumms, A. H. vV. 1965 Bacteriology of chilled water during preservation of fish. Bnll. 
Fish. Res. Stn. Ceylon Vol. ] 6, No. l, pp. 1-8. (Spoilage patterns in 
fish held in chilled water.) 
DTmAIRATNAM, lVI. 1956 Methods of collection, cost of production and bleaching of GracUctria 
lichenoicles. Frog. Rpt. Fish. Res. Stn. Ceylon, No. 2, pp. 54-56. 
(Experimental and other data obtainecl on a variety of red seaweed to 
assist its commercial exploitation.) 
DTIRAIRATNAJVI, M. 1961 Economic Marine Algae of Ceylon. I. P. F. C. Occ((,sion((,l Pape!' 
61/4; 6 pp. (A note on the distribution and commercial uses of brown 
and reel seaweeds of Ceylon.) 
DunAIRATNAM, lVI. 1964 Seaweeds (Contribution to a Symposium) Btlll. F·ish. Res. Stn. Ceylon, 
Vol. 17, No. 2, pp. 265-7. (An account of the surveys conducted 
and a note on the possible uses of seaweeds found off the coasts of 
Ceylon.) 
DunAIRATNAJ\I, lVL 1965 The ecology of C+rac-ilnria vel'l'ncos((, (Hudson) Papenfuss (formerly 
G. confer-voicles (L) ) (Greville) in Koddiyar Bay, Trincornalee. 
Bull. Fish. Res. 8tn. Ceylon. Vol. 18, No. l, pp. 29-34. (Growth and 
regeneration studies on an agar-bearing seaweed which fonns the 
basis of a commercial trade.) 
DTIRAIRATNAJ\:I, M. & MJCDCOF, J. C. 1954 Ceylon's Red Seaweed Resources. Ceylon Trade Jmw·1wl, Vol. 19, 
No. 4, pp. l-6. (A coastal survey of agar-bearing seaweeds and the 
areas found suitable for commercial exploitation.) 
DuRAIRATNAllf, 1\f. & MEDCOJr, J. C. 1955 Ceylon Moss-A Marine Resource. P?'og. Rpt. Fish. Res. Stn. Ceylon. 
GUNASEKERA, C. 1958 
GUNASEKERA, C. 1961 
GUNASEKERA, C. 1963 
GUNASEKERA, C. 1964 
GUNASEKERA, c., DE SILVA, N. N. & 
LANTZ, A. w. 1956 
GuNASEKERA, C. & DE SILvA, N. N. 1957 
No. 1, pp. 13-16. (Distribution of Ceylon's red FJeaweeds and possibi-
lities of their industrial exploitation.) 
Utilization of fish liver residues. Proc. Indo-Pacific Fish. Council 
8th Session, (Section II) pp. 89-92. (A method of converting fish 
liver residues, after extraction of oil, into stable hydrolysates for use 
as a food supplement, as sauce or in animal feeding.) 
Processing the flesh of the Pearl Oyster. P·roc. Intlo-Pacijic Fish. 
Council 9th Session (Section II) pp. 110-112. (A method of processing 
the flesh of the pearl oyster for food.) 
Small scale manufacture of crude agar from Gntcilcwic(, seaweeds. 
Bztll. Fish. Res. Stn. Ceylon., Vol. 16, No. 1, pp. 49-52. (A simplified 
process of preparing crude agar from red seaweeds using boiling vats 
and an ice-n1aking machine without the addition of chemicals.) 
Fisheries By-Products. (Symposium contribution) B1tll. Fish Res. 
Stn. Ceylon. Vol 17, No. 2, p. 257. (A note on the prevailing status 
of and practices in the fish liver oil, dried fish and sea·weed industries 
of Ceylon.) 
Preservation of fish by salting and drying. P1·og. Rpt. JNsh. Res. 
Stn. Ceylon. No.2, pp. 44-47. (A chemical and bacteriological study.) 
An experimental investigation of dry fish manufacture. 
Pa.cijic F·ish. Cotmdl., 7th Session (II-III) pp. 101-106. 
and bacteriological study.) 
Proc. Indo-
(A chemical 
GUNASEKERA, L. D. & LANTZ, A. vV. 1956 Physical analysis of trawler fish. P1·og. Rpt. F1:sh. Res. Stn. Ceylon, 
No. 2, pp. 48-50. (The proportions by weight of the component 
parts of fish from trawlers.) 
LAN'rz, A. W. 1956 Preservation of fish in chilled brine tanks during transport-Exploratory 
Vessels Frog. Rpt. Fish. Res. Stn. Ceylon, No. 2, pp. 38-43. (Quality 
of fish preserved for up to 23 days when kept on board ship in a chilled 
brine (30°F) tank whose design is illustrated.) 
LANTZ, A. W. & GUNASEKERA, C. 1955 Preservation of fish in chilled seawater. Pmg. Rpt. Fish Re8. Stn. 
Ceylon, No. I, pp. 4-6. (Quality of fish preserved for 5 to 21 days 
when held in a chilled brine tank at 30°F.) 
LANTZ, A. W. & GuNASEKERA, C. 1955 Fishery By-Products: Liquid Fish Meal. Prog. Rpt. Fish Res. Stn. 
Ceylon, No. 1, pp. 7-10. (The preparation of liquid concentrates 
from fish for use as animal food and as fertiliser.) 
LANTZ, A. W. & GUNASEKERA, C. 1955 Commercial utilization of Dolphins (Porpoises) in CeyloiL Bzt.ll. 
Fish. Res. 8tn. Ceylon, No. 3, 14 pp. (A method of harpooning 
dolphins with details of processes for converting them into various 
products.) 
LAI~Tz, A. W. & GuNASEKERA, C. 1957 Chemical Analysis of Some Ceylon Fish. B1tll. Fish. Res. 8tn. Ceylon, 
No. 5, 34 pp. (The analysis of component parts of fish for protein, 
fat, ash and n1oisture contents.) 
LANTZ, A. W. & GuNASEKERA, L. D. 1955 An investigation into the keeping qualities of ungutted fish from the 
trawlers. P1·og. Rpt. Fish. Res. Stn. Ceylon, No. 1, pp. 1-4. (The 
keeping quality of trawler fish shown to be superior when dressed 
(gutted) on board than when transported in the round (whole) condition). 
LING, S. W. 1956 Some notes on fish sauce. Unpublished. (A method of preparing 
fish sauce by salting and fermenting small fish.) 
Mom, R. W. D. 1887 Report on the working of the fish curing scheme. Sessiona,l Pape1· 
Govt. of Ceylon, No. 9, 1887. (Not available.) 
PETERSON, E. & WEimAKOON, A. H. 1951 Experiments on salting and drying of Ceylon Fish. Sessional Pape1· 
Govt. of Ceylon, No. VI, Appendix 7, pp. 91-97. (Brine salting for 
a week and air or sun drying shown to produce satisfactory cured fish 
from some local varieties.) 
RAVENSCROFT, \V. H. 1886 
HAVENSCROFT, W. H. 1888 
Report on the working of the fish curing schemes. Sessional Papet• 
Govt. of Ceylon, No. 20, of 1886. (Not available.) 
Fish curing in Ceylon. Sessional Paper Govt. of Ceylon, No. 10 of 
1888. (Not available.) 


The processing of fish and other marine resources

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The processing of fish and other marine resources

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