Fresh oil sardine, mackerel and prawn were dipped in 0.1% and 1% solutions of Na sub(2)EDTA, and stored in ice. Their storage-life was assessed by bacteriological, chemical and sensory methods. Even though EDTA treatment controlled the increase in bacterial counts and reduced TMA and TVBN production in oil sardine and mackerel, the consequent beneficial effect was not realised because of the deterioration of fat in these fishes, leading to rancidity. But, for prawn stored in ice, a dip in 1% solution of Na sub(2)EDTA enhanced the shelf-life by at least 8 days over the untreated control. EDTA absorbed by the muscle of fish and prawn during dip in Na sub(2)EDTA solution is not completely removed during their iced storage for 25 days

Gopakumar, K.

Mahadeva Iyer, K.

Surendran, P.K.

Aquatic Commons

ess E ps on e S Oil Sardine 
ella longiceps), kerel (Rastrelliger kanagurfa) 
( Metapenaeus dobson in Iced Storage* 
P. K. SURENDRAN, K. MAHADEVA IYER and K. GOPAKUMAR 
Central Institute of Fisheries Technology, Cochin - 682 029 
Fresh··oil sardine, mackerel and prawn were dipped in 0.1% and 1% solutions of 
Na2EDTA, and stored in ice. Their storage-life was assessed by bacteriological, che-
mical and sensory methods. Eventhough EDTA treatment controlled the increase in 
bacterial counts and reduced TMA and TVBN production in oil sardine and mackerel, 
the consequent beneficial effect was not realised because of the deterioration of fat in 
these fishes, leading to rancidity. But, for prawn stored in ice, a dip in 1 % solution 
of Na2EDTA enhanced the shelf-life by at least 8 days over the untreated co~tro_l. 
EDTA absorbed by the muscle of fish and prawn during dip in Na2EDTA solution is 
not completely removed during their iced storage for 25 days. 
Earlier works on chemical preservation 
of fish, particularly from the temperate 
waters, are well documented by Tarr (1961). 
Velankar & Kamasastri (1958), Surendran & 
Iyer (1971 & 1973) and Anand & Setty 
(1981 a) studied the effect of antibiotics on 
the bacteria causing spoilage of tropical fish. 
Possibility of the use of parabens and various 
other chemicals to preserve fish has been 
reported by Anand & Shetty (1981 b, c;) 
and Surendran & Gopakumar (1982 a). 
Various sodium salts of ethylene diamine 
tetra acetic acid (EDTA) h2.ve been shown 
to be effective as dipping solutions for exten-
ding the storage life of raw fish (Levin, 1967). 
Boyd & Southcott (1968) tried Na2 EDTA 
and Na2 CaEDTA for preservation of coho-
salmon: leman sole and Pacific cod during 
refrigerated storage and found that Na2 Ca-
EDTA was not effective, while Na2 EDTA 
was. Power et al (1968) found that a l % 
solution of Na4 EDTA used as a dip for had-
dock could extend the storage life in ice for 
11 days over the control. However, no 
work has so far been reported on the 
application of EDTA to preserve tropical 
fish, except the studies on the selection of 
bacterial flora in EDT A treated oil sardine, 
mackerel and prawn (Surendran&Gopakumar 
'"Formed part of the Ph. D. thesis of the first 
author (University of Kerala, Trivandrum) 
1982 b). The results of our experiments 
on the use of EDTA dips to preserve oil 
sardine, mackerel and prawn in iced storage 
are presented in this paper. 
Materials and Methods 
Fresh oil sardine, mackerel and prawn 
were procured from fishing craft operating 
off Cochin and brought to the laboratory 
within 2 to 4 h, after catch. 
Disodium ethylene diamine tetra acetate 
(Na2 EDTA) solutions (aqueous) of 1000 
p.p.m. (0.1% w/v) and 10,000 p.p.m. (1% 
w/v) strength were used as dip solutions. 
The fish/prawn were dipped in the Na2 EDTA 
solutions for 10 min., drained well and 
packed in ordinary crushed ice, in t~e fish/ 
prawn to ice ratio of 1 : 1 and stored m ther-
mocole insulated ice boxes. In all cases, 
untreated prawn/fish stored in ordinary ice 
served as the control. The samples were 
stored for 20-30 days and ice loss was made 
up by addition of crushed ice, usually on 
alternate days. 
Shelf-life of the fish and prawn was eva-
luated on the bais of total plate count (TPC), 
trimethylamine nitrogen content (TMAN), 
total volatile base nitrogen content (TVBN), 
volatile acid number (VAN), peroxide value 
(PV) and sensory qualities. The samples 
were analysed immediately on the beginning 
FISHERY TECHNOLOGY 
EFFECTIVENESS OF EDTA DIPS ON THE SHELF-LIFE OF FISH 29 
of the study and after intervals of 3 to 
5 days during storage. TPC was determined 
using seawater agar (SW A) as described 
by Surendran (1980). TMAN and TVBN 
were determined by the Conway microdiffu-
sion method (Conway, 1947) and VAN, PV, 
moisture and fat by the methods of A.O.A.C. 
(1960). Sensory evaluation of the samples 
were made in the raw and cooked state by 
a taste panel, as detailed by Surendran (1980). 
The EDTA content of the muscle was deter-
mined by the method of Sinclair & Power 
(1968). 
Results and Discussion 
(a) Shelf-life of EDTA treated.fish and prawn 
during iced storage 
(1) Oil sardine 
Tables 1 and 2 present typical results of 
the storage study of Na2EDTA treated oil 
sardines. It is evident from Table 1 that 
the bacterial counts of the control samples 
increased quite rapidly during storage, 
while the EDTA treated samples registered 
lower counts. Of the two concentrations, 
0.1 and 1% (w/v), of Na2 EDTA the sample 
dipped in 1% Na2 EDTA had lower counts 
during the storage. The organoleptic scores 
of the cooked muscle of the samples showed 
trends similar to changes in bacterial counts. 
The chemical indices like TMAN and 
TVBN (table 2) showed great variations 
among the control and treated samples. 
While the TMAN values of the control sam-
ple increased very much during storage, the 
same in the Na2EDTA treated samples 
remained low, in spite of the fact that such 
great differences were not reflected in their 
bacterial populations. However, the chan-
ges in VAN and PV values were similar 
to the bacterial counts as well as organo-
leptic scores. 
(2) Mackerel 
Tables 3 and 4 show the effect of Na2 EDTA 
treatment on bacteriological, chemical and 
organoleptic indices of mackerel held in 
ordinary ice storage. Only a dip in 1 % 
Na2EDTA solution had been tried. 
The changes in total bacterial count, 
TMAN, TVBN, VAN, PV and overall organ-
oleptic scores of the cooked muscle, were 
more or less similar to those in oil sardines. 
The TMAN values of the Na2 EDTA 
treated fish were appreciably low compared 
with the control. 
Table 1. Shelf life of Na 2EDT A treated oil sardines stored in ice 
Concentration of Na1EDTA m dip solutions 
Shelf lifr index Days of storage Control 0.1% 1% (Na2EDTA) (1000 p.p.m) (10000 p. p.m) 
0 4.08 x 103 4.08 x 103 4.08 x 103 
(before treatment) 
Total plate 4 7.25 x 104 1.68 x 103 2.06 x 103 
count/g 8 2.71 x 106 5.91 x 104 3.91 x 103 
muscle (TPC) 12 5.11 x 107 2.04 x 105 1.86 x 104 
16 3.47 X lQB 2.23 x 106 9.14 x 104 
24 2.08 x 109 1.81 x 10B 3.32 x 106 
0 20 20 20 
Overall organoleptic 4 10 12 12 
score of cooked 8 6 8 10 
muscle 12 0 2 4 
16 0 0 
24 
Vol. 22, 1985 
30 P. K. SURENDRAN, K. MAHADEVA IYER AND K. GOPAKUMAR 
Table 2. Shelf life of Na2EDTA treated oil sardines stored in ice 
Concentration of Na2EDTA in dip solutions 
Shelf life Days of Control 0.1% 1% 
index storage (No EDTA) (1000 p.p.m) (10000 p.p.m) 
TMAN TVBN TMAN TVBN TMAN TVBN 
0 
TMAN-mg (before 1.45 6.40 1.45 6.40 1.45 6.40 
% and treatment) 
TVBN-mg % 4 3.80 14.65 1.45 8.28 1.38 7.25 
8 4.70 18.10 1.60 8.16 1.49 7.68 
12 9.20 24.85 1.75 12.62 1.82 10.55 
16 14.15 29.25 2.20 16.66 1.96 10.76 
24 22.20 36.70 3.86 21.25 2.14 15.28 
VAN PV VAN PV VAN PV 
0 
VAN and (before 6.72 7.65 6.72 7.65 6.72 7.65 
PV treatment) 
4 9.86 18.50 7.79 11.28 6.68 6.52 
8 12.75 26.26 8.92 14.65 7.11 10.66 
12 15.08 29.11 11.65 18.22 9.92 12.08 
16 18.65 36.79 14.38 21.67 12.65 18.65 
24 24.28 42.34 21.97 28.08 18.78 24.34 
Table 3. Shelf life of Na 2EDTA treated mackerel during iced storage 
Shelf life index Days of Control Dipped in 1% 
storage in ice (No EDTA) Na 2 EDTA and 
stored in ice 
0 2.176 x 104 2.176 x 104 
(before treatment) 
Total plate 4 3.390 x 104 3.112 x 104 
·count/muscle 7 5.62 x 105 3.826 x 104 
12 1.903 x 107 6.071 x 104 
17 2.271 x 10s 4.795 x 106 
24 8.02 x 109 7.210 x 107 
TMAN fVBN TMAN TVBN 
0 2.52 7.90 2.52 7.90 
TMAN-mg/100 g. 
and TVBN-mg/100 g 4 3.75 11.65 2.28 6.85 
muscle 7 5.60 19.28 2.70 9.42 
12 10.38 25.20 3.04 12.75 
17 15.25 28.05 4.60 11.92 
24 19.70 40.80 6.75 15.90 
(3) Prawn 0.1 % and 1 % strength have been used for 
dip treatments. 
Results of a typical storage study of Na2-
EDTA treated prawns are presented in 
Tables 5 and 6. Na2 EDTA solutions of 
The total bacterial population of the untre-
ated prawns was always greater compared 
FISHERY TECHNOLOGY 
EFFECTIVENESS OF EDTA DIPS ON THE SHELF-LIEB OF FISH 31 
Table 4. Shelf life of Na2 EDT A treated mackerel during iced storage 
Shelf life index Days of Control (No EDTA) Dipped in 1% 
storage Na2 EDTA and 
mice VAN PV stored in ice 
VAN PV 
0 5.40 6.60 5.40 6.60 
4 8.98 11.85 6.20 6.78 
VAN and PV 7 14.25 19.70 8.45 9.25 
12 20.82 26.25 9.70 14.80 
17 26.65 31.75 14.24 16.22 
24 30.20 38.24 18.90 24.85 
0 20 20 
4 14 14 
7 8 12 
Overall organoleptic 12 4 8 
score of the 17 0 2 
cooked muscle 24 0 0 
Table 5. Shelf life of Na 2 EDT A treated prawn stored in ice 
Concentration of Na2 EDTA m dip solutions 
Shelf life index Days of 
storage Control 0.1% 1% 
(No EDTA) (1000 p.p.m) (10000 p.p.m) 
0 2.143 x 104 2.143 x 104 2.143 x 104 
(before 
treatment) 
Total plate 3 6.741 x 103 7.198 x 102 6.674 x 102 
count/g muscle 7 4.834 x 104 3.027 x 103 1.116 x 103 
12 2.771 x 106 1.716 x 105 5.815 x 104 
18 1.518 x 107 1.920 x 106 6.291 X 106 
25 1.936 x 109 6.813 X lQB 3.926 X lQB 
with the Na2EDTA treated samples. Between 
the two Na2EDTA treated samples, much 
difference in the bacterial counts was not 
noticed during the entire iced storage. 
The differences in the TMAN values 
among the control and EDTA treated sam-
ples were very significant. While a TMAN 
value of 22.86 mg/lOOg muscle of the untrea-
ted prawns was reached after 25 days in 
ice, the corresponding values in the 0.1 % 
and 1% Na2 EDTA treated prawns were 
6.95 mg% and 4.92 mg% respectively. 
The TVBN and VAN values exhibited 
the same trend as that of bacterial counts. 
Vol. 22, 1985 
Organoleptically, the Na2EDTA treated 
samples were much superior to the control. 
The control showed the symptoms of spoil-
age in 10 to 12 days of iced storage. But 
the Na2EDTA treated samples remained in 
acceptable conditions even after 16 to 18 
days in ice-storage. Even after 18 days of 
iced storage, the samples dipped in 1% Na2 
EDTA solution did not develop foul smell 
indicative of spoilage, eventhough the bacte-
ial count exceeded 6 millions per gram 
muscle. 
It can be noted from the results on oil 
sardine, mackerel and prawn (Tables 1 to 6) 
that, eventhough the bacterial counts of 
32 P. K. SURENDRAN, K. MAHADEVA IYER AND K. GOPAKUMAR 
Table 6. Shelf life of Na 2EDT A treated prawns stored in ice 
Concentration of Na2EDTA in dip solutions 
Shelf life Days of Control 
index storage (No EDTA) 
TMAN TVBN 
0 3.26 12.88 
(Before 
treatment) 
TMAN mg% 3 5.80 16.20 
and 7 7.66 17.74 
TVBNmg% 12 8.15 19.63 
18 15.20 24.14 
25 22.86 30.80 
VAN 0.S. 
0 11.60 20 
(Before 
treatment) 
VAN and 3 14.85 16 
overall 7 18.08 12 
organoleptic 12 17.60 8 
score of 18 19.25 2 
cooked muscle 25 24.15 0 
(O.S.) 
the Na1EDTA treated samples were almost 
one log cycle less than the counts of the res-
pective control samples for the same period 
of storage in ice, the rate of increase in counts 
did not markedly differ between the untreated 
and Na2EDTA treated samples. 
The improvement in shel~-life, as eviden-
ced from TMAN and TVBN values was not 
reflected in the bacterial counts. Especially 
the observation that the TMAN values were 
significantly low in Na2EDTA treated fish 
and prawns in comparison with untreated 
controls implied that EDTA might preferen-
tially affect TMA producing group of bacteria. 
Similar observations have been made by 
Pelroy & Seman (1969) in the case of EDTA 
treated petrale sole and ocean perch .fiHets. 
These authors have reported that a dip in 
1% solution of EDTA extended the shelf-
life at 0.5°C of petrale sole and ocean perch 
fillets by repressing growth of Pseudomonas 
spoilage organiEms. They found that Na2 
EDT A and Na4 EDTA were the most effe-
ctive, extending the shelf-life of ocean perch 
fillets by 7-10 days whereas Na2CaEDTA 
0.1% 1% 
(1000 p.p.m) (10000 p.p.m) 
TMAN TVBN TMAN TVBN 
3.26 12.88 3.26 12.88 
3.14 14.25 3.40 12.74 
3.70 16.06 3.40 15.80 
5.21 16.28 4.14 15.45 
5.26 17.15 4.75 17.60 
6.95 21.60 4.92 19.85 
VAN O.S. VAN O.S. 
11.60 20 11.60 20 
ll.85 16 fl.25 16 
12.08 14 11.73 14 
15.26 14 14.22 14 
17.88 8 16.75 10 
22.05 4 19.88 4 
gave a 4 day extension of shelf-life over the 
control fillets. 
Power et al (1968) have found that a 1 % 
solution of Na4 EDTA used as a dip could 
extend the storage life in ice, of haddock 
( Melanogrammus aeglefinus) .fillets by 11 
days over that of the untreated controls. 
They also noticed that TMA production 
was considerably reduced, but the growth 
of bacteria was not at all affected by EDT A 
treatment. Levin (1967), and Boyd & 
Southcott (1968) have also found that 
the rate of increase of total bacterial 
population on haddock and salmon fillets 
was not affected by Na4 EDTA. 
The fact that uncharacteristic, although 
not unpleasant tastes were noted in later 
stages of strorage of EDTA treated fish and 
prawn suggested that the normal spoilage 
pattern was altered by EDTA treatment. 
This idea is further reinforced by the fact 
(as pointed out earlier) that there was a 
definite repression of TMA values in the 
treated samples in comparison with untreated 
FISHERY TECHNOLOGY 
EFFECTIVENESS OF EDTA DIPS ON THE SHELF-LIFE OF FISH 33 
controls, but at the same time, there was no 
significant difference in total counts. It is 
possible that EDT A has a selective inhibitory 
action on the growth of TMA producing 
bacteria, thus allowing competitive strains 
to grow at a faster rate (Power et al. 1968). 
Even though the data presented in Tables 
1 to 4 show that EDTA treatments controlled 
the increase in bacterial counts and reduced 
the TMAN and TVBN production in oil 
sardines and mackerel, the consequent bene-
ficial effect was not realised because of the 
deterioration of fat in these fishes, leading 
to rancidity, as evident from the rapid increase 
in VAN and PV values in control and treated 
samples. Thus EDTA treatment is not use-
ful in extending the shelf-life of fatty fishes. 
But, for prawns stored in ice, a dip in 1% 
solution of EDTA enhanced the shelf-life 
by at least 8 days over the untreated control. 
( b) Changes in the EDT A content of the 
muscle of EDT A treated fish and prawn 
during ice storage 
Concentration of EDTA absorbed by the 
muscle of oil sardines and prawns during the 
dip in Na2 EDTA solutions and the changes 
in EDTA contents during subsequent storage 
in ordinary ice are given in Tables 7 and 8. 
The quantity of EDTA absorbed by the 
muscle of both oil sardines and prawns, was 
directly dependent on the concentration of 
EDT A in the dip solutions; higher the con-
centration of EDT A in dip solutions, the 
greater the amount absorbed. 
TabHe 7. EDT A content of the muscle of oil 
sardines dipped in Na 2 EDT A 
solutions and· subsequently stored 
in ice 
Days of 
storage 
Just after 
dip 
4 
12 
24 
EDTA concentration 
micrograms/g muscle 
Dipped in 
0.1% Na2 EDTA 
solution 
110 
102 
95 
80 
Dipped in 1% 
Na2EDTA 
solution 
326 
290 
246 
212 
Vol. 22, 1985 
Table 8. EDT A content· of the muscle of 
prawn dipped in Na2 EDT A solu-
tions and subsequently stored in ice 
Days of 
storage 
Just after 
dip 
3 
12 
25 
EDTA concentration 
micrograms/g muscle 
Dipped in 
0.1% Na2 
EDTA 
solution 
196 
191 
165 
157 
Dipped in 1% 
Na2 EDTA 
solution 
432 
426 
384 
358 
The EDTA content of the muscle of oil 
sardines, immediately after dip was 110 p.p.m 
in the case of dipping in 0.1% Na2 EDTA 
solution and 326 p.p.m in the case of dipping 
in 1% Na2 EDTA solution, the dip time 
being I 0 min. On storage :in ice, the EDT A 
content decreased, but not app1eciably. 
After 24 days of iced storage, the EDTA 
content of the muscle was 80 p.p.m and 
212 p.p.m, for oil sard\nes dipped in 0.1% 
Na2 EDTA solution and 1% Na2 EDTA 
solution respectively. 
The amount of EDT A absorbed by prawn 
muscle during dip in Na2EDTA solution 
was greater compared with that absorbed 
by fish. The EDT A content of prawns 
dipped in 0.1~~ Na2 EDTA solution for 10 
min. was 196 p.p.m, which on storage in 
ice for 25 days, was depleted to 157 p.p.m. 
Whereas, 432 p.p.m of EDTA was absorbed 
by prawn muscle dipped in 1% Na2 EDTA 
solution for 10 min. and on storage in ice 
for 25 days, it decreased to 358 p.p.m. 
The fact that only a small percentage of 
EDTA absorbed by the muscle, was washed 
away during icedstorage might indicate that 
EDTA was bound or absorbed to the muscle 
of oil sardine and prawn. That higher 
amount of EDTA was absorbed by prawn 
muscle might be due to the fact that, in the 
case of prawn, the muscle was more exposed 
and that, owing to the small size of prawns 
compared with oil sardines, relatively larger 
areas were exposed to EDT A solution. 
34 P. K. SURENDRAN, K. MAHADEVA IYER AND K. GOPAKUMAR 
Pelroy & Seman (1969) found that the 
mean EDTA content of ocean perch fillets 
dipped in 1 ~~ solution was 305 p.p.m for 
the Na4 EDTA treated fish, 396 p.p.m for 
the Na2 EDTA treated fish and 411 p.p.m 
for the Na2 CaEDTA treated fish. The resi-
dual EDTA contents of haddock fillets 
treated with 1% Na4 EDTA solution were 
187 to 333 p.p.m while in haddock fillets 
treated with 1% Na2 CaEDTA solution, the 
residual EDT A contents varied between 
240 and 370 p. p.m. (Power et al 1968). They 
also found that soft fillets had higher resi-
dual EDT A contents than firm fillets of the 
same size. Boyd & Southcott (1968) have 
reported that the concent::-ation of Na2 Ca 
EDT A in cod samples after immersion for 
one min. in 0.5% and 1% Na 2 CaEDTA 
solution was 600 p.p.m and 750-810 p.p.m 
respectively. The concentration of EDTA 
in treated samples would undoubtedly be 
less if fish samples were larger in size. 
However, the EDTA absorbed by the muscle 
of oil sardines and prawns, in this study was 
found to be comparatively less than those 
reported by the above workers. 
The authors are thankful to the Director, Central 
Institute of Fisheries Technology, Cochin-682 029 
for the facilities provided. 
References 
Anand. C. P. & Setty. T. M. R. (1981 a). 
Fish. Technol. 18, 41 
Anand. C. P. & Setty. T. M. R. (1981 b). 
Fish. Technol. 18, 47 
Anand. C. P. & Setty. T. M. R. (1981 c) 
Fish. Technol. 18, 55 
A. 0. A. C. (1960) Official Methods of 
Analysis, Association of Official Ana-
lytiCal Chemists. A. 0. A. C. Washing-
ton D. C. 
Boyd. J. W. & Southcott, B. A. (1968) 
J. Fish. Res. Bd. Canada 25, 1753 
Conway (1947) Microdfffusion Analysis 
and Volunzetric Error. Porch Croskey 
and Sockwood & Son Limited, London 
Levin, R E. (1967) J. Milk. Fd Technol. 
30, 277 
Pelroy, G. A. & Seman (Jr.) J. P. (1969) 
J. Fish. Res. Bd. Canada. 26, 2651 
Power, H. E., Sinclair, R. & Savagaon, K. 
(1968). J. Fish. Res. Bd. Canada. 25, 
2071 
Sinclair, R. & Power. H. E. (1968) Colo-
rimetric Determination of EDTA Salts 
on Haddock, Cod and Flounder. Tech-
nical report no. 68. Fisheries Research 
Board of Canada., Halifax Laboratory, 
Halifax, N. S. 
Surendran, P. K. (1980). Chemical Pre-
servatives in Relation to Control of Micro-
bial Changes in Fishery Products. 
Ph.D. thesis, University of Kerala, 
Tri van drum 
Surendran, P. K. & Gopakumar, K. (1982 a) 
Preservation of oil sardines with propyl 
paraben dips. Symposium on 'Harvest 
and Post-Harvest Technology of Fish' 
held at Cochin from 24- 27 Nov. 
1982, SOFT (I), Cochin 
Surendran, P. K. & Gopakumar, K. (1982b) 
Fish. Technol. 19, 33 
Surendran, P. K. & Mahadeva Iyer, K. (1971) 
Fish. Technol. 8, 55 
Surendran, P. K. & Mahadeva Iyer, K. (1973) 
Fish. Technol. 10, 110 
Tarr. H. L. A. (1961). Chemical Control 
of Microbiological Deterioration. In 
'Fish as Food'. Vol. I. pp. 639-680. 
(Borgstrom G. Ed.) Academic Press. 
New York and London 
Velankar, N. K. & Kamasastri, P. V. (1958). 
Indian. J. Fish. 5, 150 
FISHERY TECHNOLOGY 


Effectiveness of EDTA dips on the shelf-life of oil sardine (Sardinella longiceps), mackerel (Rastrelliger kanagurta) and prawn (Metapenaeus dobsoni) in iced storage

http://aquaticcommons.org/18471/1/FT22.1_028.pdf

Effectiveness of EDTA dips on the shelf-life of oil sardine (Sardinella longiceps), mackerel (Rastrelliger kanagurta) and prawn (Metapenaeus dobsoni) in iced storage

Abstract

Similar works

Full text

Available Versions

Aquatic Commons