Lantern-fish, an under-utilised fish is present in abundance, all the year round in tropical and sub-tropical waters. Biochemical and microbiological studies carried out on lantern fish, caught from the Gulfs of Oman and Aden are reported in this paper

Gopakumar, K.

Lekshmy Nair, A.

Nair, P.G.V.

Radhakrishnan, A.G.

Ramachandran Nair, K.G.

Ravindranathan Nair, P.

Aquatic Commons

17 
tudies on lantern Fish (Benthosema pterotum) 
I. iochemical and Microbiological Investigations 
K. GOPAKUMAR, K. G. RAMACHANDRAN NAIR, P. G. VISWANATHAN NAIR, 
A. LEKSHMY NAIR, A. G. RADHAKRISHNAN and P. RAVINDRANATHAN NAIR 
Central Institute of Fisheries Technology, Cochin - 682 029 
Lantern-fish, an under-utilised fish is present in abundance, all the year round in 
tropical and sub-tropical waters. Biochemical and microbiological studies carried out 
on lantern fish, caught from the Gulfs of Oman and Aden are reported in this paper. 
Lantern fish ( Myctophidae) i~ an import-
ant fish caught from the mesopelagic zone. 
They are widely distributed and occur all 
the year round with maximum density in 
the Gulfs of Oman and Aden. The pot-
ential yield of fish from mesopelagic zone 
is tentatively estimated to be 100 million 
tonnes per year (Eddie, 1976). Mesopela-
gic fish are reported to contain fairly 
high quantities of wax esters and when 
eaten in large quantities cause diarrhoea and 
seborrhoea in animals (Teutscher, 1979). 
Though abundant in distribution, very little 
is known about the biochemistry and tech-
nology of utilisation of lantern fish. The 
present paper reports the biochemical and 
microbiological studies carried out by the 
authors to develop various methods of pro-
cessing and utilization of lantern fish. 
Materials and Methods 
The fish was caught by fishing vessel Dr. 
F. Nansen from Gulf of Oman in August 
1979 and frozen blocks of the fish kept in 
cold storage at Sri Lanka were air lifted to 
Cochin under refrigeration and stored at 
-20°C. The frozen blocks were thawed, 
ground uniformly in a meat mincer and 
mixed thoroughly. Samples were taken as 
and when required. 
Moisture, crude protein, total ash, acid in-
solube ash and fat were estimated according 
to the official methods of AOAC (1975). 
The ash dissolved in 1 N hydrochloric acid 
was used for the determination of the mineral 
content using flame photometer. . Fractiona-
tion of proteins was achieved by successive 
extraction with buffers of varying ionic 
Vol. 20, 1983 
strength. Further study on the protein fra-
ctions was carried out by disc electrophoresis 
in polyacrylamide gel, following the method 
of Ornstein & Davies (1964). 
10 g of the fish muscle was aseptically 
removed from the frozen fish block. Total 
viable bacterial count was determined by the 
pour plate method using tryptone glucose 
agar. In addition, tests were simultaneously 
carried out for E. coli., faecal streptococci 
and coagulase positive staphylococci by 
standard methods recommended by APHA 
(1966). 
About 1 kg of fish was comminuted to a 
fine paste and the lipids were extracted from 
the minced meat by the method of Bligh & 
Dyer (1959) using the solvent mixture of 
chloroform and methanol (2: 1 ). The lipids 
were quantitatively recovered from the chlo-
roform layer, concentrated in a current of 
nitrogen and dried in vacuum. Analysis 
of the lipids for iodine value (Wijs'), saponi-
fication value, content of unsaponifiable 
matter and free fatty acids were carried out 
as per AOCS (1957). 
The fatty acids liberated from the lipid 
by saponification with methanolic KOH 
were converted to their methyl esters by 
treatment with boron trifluoride-methanol 
reagent (AOAC, 1975). The fatty acid 
methyl esters were analysed on a stainless 
steel column (1.8 m x 6 mm o.d.) filled with 
chromosorb G (70-80 mesh) acid washed 
and DMCS treated, coated with silar 10 C 
(10%), using a (Tosniwal India Ltd.) gas 
chromatograph equipped with flame ionisa-
tion detector, dual column and fitted with a 
18 K. GOPAKUMAR, K.G.R. NAIR,P.G.V. NAIR, A.L. NAIR, 
A. G. RADHAKRISHNAN AND P.R. NAIR 
Varian strip chart recorder (10 mv). The 
operating conditions were: column tempera-
ture, 190°C; injection port temperature, 
250oC; detector temperature, 250°C; carrier 
gas (nitrogen) flow rate, 50 ml/min. The 
fatty acid composition was determined as 
described earlier (Gopakumar & Nair, 1972). 
Results and Discussion 
Chemical Composition 
The proximate composition (Table 1) 
show that lantern fish is comparable to 
other fishes in moisture, protein, fat and 
ash contents (Kutty Ayyappan et al. 1976). 
The average mineral content from three 
composite samples (Table 2) indicate that 
the fish is a good source for sodium, 
potassium and calcium. The levels of 
potassium and sodium are almost identi-
cal, which appears to be a special 
feature of this fish. 
Table 1. Proximate composition of lantern 
fish ( g/100 g whole minced wet fish) 
Table 2. 
Sample 1 
Moisture 
Protein 
Fat 
Ash 
77.2 
16.1 
3.4 
3.5 
Mineral content (mgj100g fish) 
ash from lantern fish 
Sodium Potas- Calcium 
sium 
184.6 137.4 137.4 
Sample 2 167.0 118.0 137.5 
Sample 3 100.0 119.0 110.0 
of 
Studies on protein distribution revealed 
that sarcoplasmic and myofibrillar proteins 
were in the usual range seen in most fishes. 
Of the total proteins, 44.6% was denatured 
protein. This obviously is due to the long 
frozen storage of the sample studied. It was 
also observed that the water soluble nitrogen 
fraction formed 25.6% of total nitrogen. 
Electrophoresis of the aqueous extract and 
sarcoplasmic protein extract showed only 
four protein bands of low molecular weights. 
Of these, the one having the highest mole-
cular weight was seen to be present in larger 
concentration compared to the other three 
proteins. 
Microftora of the fish 
Since the fish was under frozen storage 
for a considerable period of time, bacterio-
logical analysis, both quantitative and qua-
litative were performed. Native flora of the 
fresh fish however could not be studied. The 
total viable count of the frozen fish was 
2.9 x 103 organisms per g which is within 
the safe limit as far as total viable count is 
concerned. Coliforms, faecal streptococci 
·and coagulase positive staphylococci were 
not detected. The bacterial isolates consis-
ted mainly of one type of organism, gram 
negative non-motile rods, identified as Achro-
mobacter sp. 
Lipid and fatty acid composition 
Chemical analysis of the lipid (Table 3) 
shows that the percentage of unsaponifiable 
matter, 4.0, is well within the limits usually 
seen in most fishes. The relatively high 
content of free fatty acids seen in this case 
indicates that the fish has undergone lipid 
hydrolysis to a considerable extent. This 
is understandable in view of the fact that this 
sample was under frozen storage for a long 
time. 
Table 3. Characteristics of lantern fish lipid 
Total lipids 
U nsaponifiable 
matter 
C% of total 
lipid) 
Iodine value 
(Wijs') 
Saponification 
value 
Free fatty acid 
(oleic acid %) 
3.4 g/100 g 
wet fish 
4.00 
1.45 
200.00 
8.00 
FISHERY TECHNOLOGY 
STUDIES ON LANTERN FISH 
Table 4. Fatty acid composition of lantem 
fish fat 
Fatty acid Composition 
·chain length weight % 
c12:o 0.2 
C13:o 0.1 
Cl3:1 0.1 
Ct4:0 4.5 
C1s:o 2.2 
C1s:1 0.9 
C16:o 26.7 
C16:1 2.9 
C11:0 7.9 
C1s:o 8.3 
C1s:1 13.2 
C1s:2 2.3 
C2o:1 2.2 
C2o:2 1.2 
C1s:3 1.8 
C1s:4 1.7 
C22:1 0.7 
C2o:3 2.7 
C2o:4 1.0 
C2o:s 4.8 
c22:2 1.3 
C:~2:3 0.9 
C22:4 1.7 
C22:s 0.7 
c22:6 10.0 
The fatty acids liberated from the lipids 
of lantern fish are tabulated in Table 4. G LC 
of the fatty acid methyl esters of the lipids 
of lantern fish showed that C 16 saturated 
acid is the major acid accounting for over 
25% of the total acids. Cl4:0 acid accounted 
for 4.5% and C22:6 for 10%. This cannot 
be taken as the true lipid fatty acid compo-
sition, since the fish was held under frozen 
storage for more than one year. Consideable 
lipid hydrolysis would have taken place, as 
is indicated by the high FF A value (8) which 
is usually lower than 2 in fresh fish lipids. 
In many ways, the fatty acid composition is 
comparable to that of most fish species from 
marine sources. (Nair & Gopakumar, 1977). 
Vol. 20, 1983 
19 
On the whole it can be seen that lantern 
fish resembles most marine fish with regard 
to its biochemical constituents and chara-
cteristics. Thus the fish can be successfully 
exploited for processing to various products 
which can be used as a food for both man 
and animals. 
The authors express their gratitude to Director, 
Central Institute of Fisheries Technology, Cochin 
for permission to publish this paper and to Shri 
K. M. Iyer for bacteriological analysis of the fish. 
They are deeply indebted to Mr. David James, 
Chief, Fisheries Industries Division, FAO, Rome 
for supply of the lantern fish used for this study. 
References 
AOAC (1975) Official Methods of Ana-
lysis (Horwitz, W., Ed.) 12th edn., Asso-
ciation of Official Analytical Chemists, 
Washington 
AOCS (1957) Official and Tentative 
Methods of the American Oil Chemists' 
Society (Mehlenbacher, V. C. & Hopper, 
T. H., Eds.) 2nd edn., American Oil 
Chemists' Society, Chicago 
APHA (1966) Recommended Methods for 
the Microbiological Examination of 
Foods. 2nd edn., American Public 
Health Association Inc., New York 
Bligh, E. G. & Dyer, W. J. (1959) Can. J. 
Biochem. Physiol. 37, 911 
Eddie, G. (1976) The Potential of the 
Fisheries to Provide Increased Food 
Supplies for Developing Countries and 
the Requirements for Investment, F AO 
FII/C 343 
Gopakumar, K. & Nair, M. R. (1972) J. 
Sci. Fd Agric. 23, 493 
Kutty Ayyappan, M. P., Shenoy, A. V. & 
Gopakumar, K. (1976) Fish. Techno!. 
13, 153 
Nair, K. G. & Gopakumar, K. (1977) J. 
Fd Sci. Techno!. 14 (6), 1 
Ornstein, L. & Davies, B. J. (1964) In Disc 
Electrophoresis. Reprinted by Distil-
lation Products Industries, Rochester, 
New York 
Teutscher, F. (1979) 'Preliminary Investi-
gations with Respect to the Utilization 
of M esopelagic Fish from the Gulf of 
Oman and the Arabian Sea' Fisheries 
Industries Division, F AO, Rome. (Pri-
vate communication) 


Studies on lantern fish (Benthosema pterotum) 1. Biochemical and microbiological investigation

http://aquaticcommons.org/18399/1/FT20.1_017.pdf

Studies on lantern fish (Benthosema pterotum) 1. Biochemical and microbiological investigation

Abstract

Similar works

Full text

Available Versions

Aquatic Commons