































Highlights in BioScience
ISSN:2682-4043
DOI:10.36462/H.BioSci.202305

Research Article

Open Access

1 Laboratory of Ecology, Biology and Physiology

of Aquatic organisms, Tunis Faculty of Science,

University of Tunis El Manar- 2092 Tunis-

Tunisia.
2 University of Carthage, Higher Institute of

Fisheries and Aquaculture of Bizerte (ISPAB),

Errimel, B.P.15. 7080, Bizerte, Tunisia.
3 Laboratory of Fisheries Sciences, National

Institute of Marine Sciences and Technologies

(INSTM), 28 Rue du 2 mars 1934, Salammbô

2025, Tunis, Tunisia.

* To whom correspondence should be
addressed: ferielghribi@yahoo.fr

Editor: Alsamman M. Alsamman, International
Center for Agricultural Research in the Dry Areas
(ICARDA), Giza, Egypt.

Reviewer(s):
Khaled H. Radwan, Agricultural Genetic
Engineering Research Institute (AGERI),
Agricultural Research Center (ARC), Giza, Egypt.

Ahmed E. Nassar, Department of Biotechnology,
Faculty of agriculture, Mansoura University,
Dakahlia, Egypt.

Received: March 29, 2023

Accepted: November 10, 2023

Published: November 22, 2023

Citation: Ghribi F, Chetoui I, Bejaoui S, Belhassen
D, Trabelsi W, Fouzai C, Mili S, Soudani
N. Comparison of lipid content and fatty acid profile
of fresh and frozen blue swimming crab Portunus
Segnis. 2023 Nov 22;6:bs202305

Copyright: © 2023 Ghribi et al.. This is an open
access article distributed under the terms of the
Creative Commons Attribution License, which per-
mits unrestricted use, distribution, and reproduction
in any medium, provided the original author and
source are credited.
Data Availability Statement: All relevant data are
within the paper and supplementary materials.
Funding: The authors have no support or funding
to report.
Competing interests: The authors declare that they
have no competing interests.

Comparison of lipid content and fatty acid profile of fresh and frozen
blue swimming crab Portunus Segnis

Feriel Ghribi*,1
><, Imene Chetoui 1

>< , Safa Bejaoui 1,2
>< ,

Dalya Belhassen 1
><, Wafa Trabelsi 1

><, Chaima Fouzai 1
>< ,

Sami Mili 2,3
><, Nejla Soudani 1

><

Abstract

The blue swimming crab Portunus segnis has a great economic interest in local
and foreign fishing markets and is in high demand by consumers. The aim of the
present work was to evaluate the change in total lipid (TL), fatty acids composition
and nutritional quality indices (NQI) of the meat of blue swimming crab Portunus
segnis after freezing at -18◦C for 15, 30, 60 and 90 days. The comparison of fresh and
frozen crabs showed that freezing had significant effects on the nutritional quality of
this marine product. Lipid peroxidation was enhanced during the freezing process.
Total lipid content decreased significantly as a function of days of storage, especially
from 30 days. A significant change was also observed in the fatty acid composition of
frozen crab meat. During the freezing process, saturated fatty acids (SFA) increased
significantly, while polyunsaturated fatty acids (PUFA) and monounsaturated fatty
acids (MUFA) decreased. We can conclude that storage of blue crab P. segnis at
-18◦C was not efficient enough for long preservation, as it has a strong effect on the
deterioration of the nutritional quality of the meat over time. Frozen crabs should
preferably be consumed within 15 days of storage. Our research targets both domestic
and international consumers of this crab, with a specific focus on restaurants and
hotels that incorporate this item into their menus. We recommend that consumers
of this product exercise increased caution regarding the advantages and drawbacks
associated with the freezing techniques employed.

Keywords: Portunus segnis, frozen storage, lipid content, fatty acids profile, lipid peroxidation,

nutritional quality

Introduction
In the Mediterranean Sea, crustaceans are the second most abundant taxon of confirmed non-

native species [1]. In Tunisian waters, a total of 163 alien species have been reported, with crus-

taceans dominating with a 24% share of reported alien species [2]. Crabs are common in all regions

of the world and are found in freshwater, brackish water, and marine habitats. However, other species

are also found on land, where they can live hundreds of kilometers from aquatic habitats [3]. Crabs

occupy a variety of trophic niches; they also play an important ecological role in aquatic ecosystems

[4]. The blue swimming crab, formerly called P. pelagicus [5], is one of the first Lessepsian invaders.

In Tunisian waters, the occurrence of P. segnis was first reported in 2014 by [6] in shallow, sandy

areas with seagrass beds and algae. Since 2015, the number of P. segnis individuals in the Gulf of

Gabes has greatly increased [7] and includes much larger areas on the southeastern coasts of Tunisia.

P. segnis is in high demand by consumers and is regularly sold at all local fish markets.

Crustaceans are recommended for human consumption because of their beneficial and healthy

properties [8]. They are rich in polyunsaturated fatty acids such as EPA (ecosapentaenoic fatty acid)

and DHA (decosahexaenoic fatty acid). EPA and DHA are very useful for human health due to their

anti-inflammatory, antithrombotic, and antiarrhythmic properties. In recent years, the increasing

consumption of seafood has led to an improvement in preservation methods to obtain products of

high nutritional quality.

Highlights in BioScience Page 1 of 8 November 2023|Volume 6

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https://creativecommons.org/licenses/by/4.0/
mailto:ferielghribi@yahoo.fr
https://orcid.org/0000-0001-9350-7510
mailto:chetouiimene@gmail.com
https://orcid.org/0000-0002-2259-5397
mailto:safa.bejaoui@fst.utm.tn
https://orcid.org/0000-0002-7946-2763
mailto:dalya.belhassen@gmail.com
https://orcid.org/0009-0003-5518-1435
mailto:wafa.trabelsi@etudiant-fst.utm.tn
https://orcid.org/0000-0002-1114-4080
mailto:fouzai.chaima93@gmail.com
https://orcid.org/0000-0001-7588-1859
mailto:sami_mili@yahoo.fr
https://orcid.org/0000-0002-2625-8064
mailto:nejla.soudani@tunet.tn
http://bioscience.highlightsin.org/


Ghribi et al., 2023 Comparison of lipid content and fatty acid profile of fresh and frozen blue swimming crab Portunus Segnis

Freezing is considered the most suitable and effective method
to preserve food quality [9]. This method is most suitable for
long-term preservation of seafood because it preserves the organo-
leptic properties of the food well [10]. However, the formation
of ice crystals under freezing conditions could lead to cell crack-
ing and tissue destruction [11]. Fishery products are indeed sub-
ject to natural postmortem degradation due to endogenous and
exogenous reactions [12]. This phenomenon is largely depen-
dent on storage conditions, which further promote oxidation re-
actions.

Due to the lack of information on the effects of freezing on
blue swimming crab meat, lipid content, fatty acid composition,
NQI, and lipid peroxidation markers in P. segnis after freezing
at -18◦C for 15, 30, 60, and 90 days were studied in this work.

Material and methods
Sampling Site

Although the Gulf of Gabes is considered one of the most
productive fishing areas in Tunisia, it is subject to numerous
anthropogenic impacts that affect its biodiversity [13]. In the
present study, our samples were collected in the commercial port
of "Ghannouch" in the Gulf of Gabes (34o 05’ 37”N, 10o 26’
13”E) (Figure 1).

Figure 1. Sampling Site - Location of sample collection in the Gulf of Gabes.

Preparation of the Samples
Fifty adult specimens were collected in January 2018 to study

the effects of freezing on the blue crab Portunus segnis. The

crabs ranged in length from 41.75 to 62.9 mm, width from 85.8
to 130 mm, and total weight from 29.3 to 114.1 g. The samples
were immediately brought to the laboratory in a cool box. Then,
the crabs were well cleaned, packed in plastic bags, labeled, and
frozen at -18oC for 15, 30, 60, and 90 days. For each period,
the meat of ten whole animals was homogenized using a grinder
(UltraTurrax®) and prepared for lipid and fatty acid content anal-
ysis. One batch of 10 animals was analyzed fresh.

Lipid Content
Total lipid content in fresh and frozen tissue samples was

determined according to the method of Folch et al. (1957) us-
ing a mixture of chloroform-methanol (2v/1v) and 0.01% butyl-
hydroxytoluene (BHT). The volume of chloroform-methanol ex-
traction solvent is proportional to the weight of the organ: 30 ml
of extraction solvent for 1 g of the tissue. Elimination of pro-
teins was performed after the addition of a 15% NaCl solution.
After centrifugation at 3000 rpm for 15 min, the organic phase
was stored in previously weighed flasks.

Fatty Acid Profile
Fatty acid methyl esters (FAME) were determined by gas

chromatography (HP 6890 GC). Qualitative identification of fatty
acids (FA) was performed using a standard "PUFA3" chromatogram
of menhaden oil from SUPELCO injected under the same chro-
matographic conditions. The determination of a fatty acid (X)
is done by comparing its retention time with the time indicated
in the "PUFA3" chromatogram. The areas of the peaks are pro-
portional to the amounts of the corresponding fatty acids. In our
study, the fatty acids in percent (%) were calculated from the ar-
eas of the peaks of the chromatogram and the internal standard
(C19:0 Belefonte PA. USA. CRM47885), the amount of which
is known in µg.

Nutritional Quality Indices (NQI)
The NQI of the fresh and frozen samples were determined

using the indices mentioned by [14; 15; 16; 17; 18] and summa-
rized in Table 1.

Lipid Peroxidation
Peroxide Value (PV)

PV was estimated based on the AOCS (1989) method. Re-
sults were expressed in ml g-1 and calculated according to equa-
tion (E1):

PV = (sample titration−blank titration)×Nthiosulfate×1000
sample weight (E1)

Thiobarbituric Acid Reactive Substances (TBARS)
TBARS were determined according to the AOCS method

(1989), and results were expressed in mg kg-1.

Statistical Analysis
Data were presented as means ± standard deviations (SD) of

10 replicates for lipids, FA, and lipid peroxidation markers and

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Ghribi et al., 2023 Comparison of lipid content and fatty acid profile of fresh and frozen blue swimming crab Portunus Segnis

Table 1. Nutritional Quality Indices (NQI)

References Index Calculation

Marques et al. 2010 [14] n-3
n-6

Marques et al. 2010 [14] PUFA
SFA

Unusan 2007 [15] EPA + DHA

Ulbricht and Southgate 1991[16] AI = (4×C14:0)+C16:0+C18:0
ΣMUFA+Σ PUFA n−6+Σ PUFA n−3

Ulbricht and Southgate 1991 [16] TI = C14:0+C16:0+C18:0
0.50×MUFA+0.5× PUFA n−6+3× PUFA n−3+ PUFA n−3

PUFA n−6

Rodriguez et al. 2007 [17] PI = C20:5n−3+C22:6n−3
C16:0

Fernandez et al. 2014 [18] h/H = C18:1n−9+C18:2n−6+C20:4n−6+C18:3n−3+C20:5n−3+C22:5n−3+C22:6n−3
C14:0+C16:0

analyzed with STATISTICA 8 software (Stat-Soft Inc). Homo-
geneity and normality of variables were tested with the Shapiro
test. Significant differences were found at the 5% level. Re-
sults were checked with one-way analysis ANOVA and post-hoc
Tukey and Kruskall-Wallis test. To show possible correlations
between biochemical parameters of raw and frozen crabs, prin-
cipal component analysis (PCA) was performed.

Results
Lipid content

Total lipid content in fresh blue crab was estimated to be
41.85 ± 4.33 mg/g (Figure 2). A significant decrease in lipid
content was observed in the flesh of crabs frozen at −18◦C after
30, 60, and 90 days of storage (27.28, 17.08, and 14.57 mg/g
weight, respectively).

Figure 2. Lipid content of raw and frozen blue crab during freezing (−18◦C)

FA composition
The FA profile of fresh and frozen crabs, expressed as a

percentage of the total identified FA, was presented in Table
2. For fresh crabs, PUFA accounted for 33.60% of the total
FA, followed by SFA (20.49%) and MUFA (15.78%). Palmitic
acid (C16:0; 6.28%) and arachidic acid (C20:0; 5.82%) dominated
SFAs in fresh crab meat. PUFA were dominated by eicosenoic
acid (C20:1; 6.26%), oleic acid (C18:1; 2.14%), and palmitoleic
acid (C16:1; 2.87%), while alpha-linolenic acid (C18:3n−3; 7.82%),
docosahexaenoic acid (DHA; 6.23%), eicosapentaenoic acid (EPA;
4.58%), and eicosatetraenoic acid (C20:4n−3; 3.63%) were the
most abundant FAs in PUFA (Table 2). In frozen crabs, PUFA
and MUFA significantly decreased (p < 0.05), while SFA in-
creased. In SFA, both C16:0 and C18:0 fatty acids significantly
increased by 60.03% and 158.30%, respectively, after 90 days
of freezing (p < 0.05). In contrast, PUFA significantly de-
creased after 90 days of storage (3.44%). This decrease was
influenced by the decrease in major FA such as C16:1 and C18:1

(0.28% and 0.63%, respectively). Frozen crabs showed a signifi-
cant decrease in n-3 PUFA after storage. The levels of omega-3
(PUFA n-3) and omega-6 fatty acids (PUFA n-6) in the fresh and
frozen crabs are shown in Table 2. DHA and EPA reached their
lowest levels of 0.61% and 0.56%, respectively, after 90 days
of storage compared to the fresh samples (6.23% and 4.58%, re-
spectively). In contrast, n-6 PUFAs in frozen crabs showed a
different variation with a significant increase (p < 0.05) during
the freezing process and reached their high values after 90 days
of storage (16.19%) compared to fresh samples (2.92%).

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Ghribi et al., 2023 Comparison of lipid content and fatty acid profile of fresh and frozen blue swimming crab Portunus Segnis

Table 2. Fatty acid profile of fresh and frozen crabs for 15, 30, 60 and 90 days.

Fatty acids Fresh 15 days 30 days 60 days 90 days

C14:0 1.67±0.28 2.38±0.36* 3.13±0.09*** 4.50±0.22*** 5.23±0.07***

C15:0 1.04±0.13 0.74±0.39*** 2.12±0.05*** 2.93±0.46*** 4.17±0.06***

C16:0 6.28±0.25 7.74±0.61** 8.74±0.75*** 9.18±0.51*** 10.05±0.58**

C17:0 1.86±0.24 1.26±0.29 1.56±0.24*** 4.05±0.50*** 5.62±0.30***

C18:0 2.14±0.32 2.91±0.91 3.16±0.13* 5.02±0.50*** 7.00±0.71***

C20:0 5.82±0.63 5.89±0.59 6.46±0.28 8.10±0.31*** 9.65±0.45***

C22:0 1.41±0.06 1.62±0.48* 2.95±0.36*** 5.54±0.97*** 8.59±0.20***

C14:1 1.61±0.13 1.30±0.01** 0.87±0.06*** 0.64±0.12*** 0.16±0.03***

C15:1 0.57±0.38 0.66±0.22 0.23±0.03 0.18±0.01 0.14±0.05

C16:1 2.87±0.07 2.66±0.29 1.04±0.14*** 0.85±0.06*** 0.28±0.04***

C18:1 2.14±0.32 1.76±0.10 1.31±0.29* 0.87±0.09*** 0.63±0.09***

C20:1 6.26±0.94 5.83±0.68 4.24±0.43*** 2.78±1.05*** 1.64±0.25***

C22:1 2.33±0.57 2.22±0.27** 1.89±0.54 1.30±0.17*** 0.59±0.06***

C16:2n-4 3.17±1.58 0.33±0.20** 0.49±0.05*** 0.25±0.02* 0.09±0.01***

C16:3n-4 1.39±0.31 1.54±0.40 0.47±0.15*** 0.16±0.02*** 0.11±0.01***

C18:2n-6 0.64±0.05 0.86±0.03** 0.91±0.08*** 1.76±0.10* 2.68±0.29***

C18:3n-4 1.82±0.74 0.97±0.08* 0.54±0.15* 0.48±0.05*** 0.14±0.02***

C18:3n-3 7.82±0.26 7.48±0.47** 5.95±0.71*** 2.56±0.36*** 0.27±0.06***

C20:3n-6 1.71±0.09 2.22±0.15** 3.96±0.29* 5.28±0.97*** 7.05±0.06***

C20:4n-6 0.57±0.03 1.56±0.30** 2.52±0.61*** 4.96±0.18*** 6.46±0.33***

C20:3n-3 2.06±0.01 2.52±0.30* 2.77±0.42 1.22±0.09*** 0.56±0.01***

C20:4n-3 3.63±0.45 3.61±0.36 2.26±0.12* 1.98±0.30*** 0.61±0.06***

C20:5n-3 4.58±0.51 4.87±0.04 2.52±0.61*** 1.52±0.74*** 0.61±0.06***

C22:6n-3 6.23±0.38 5.51±0.48* 3.24±0.32*** 1.98±0.12*** 0.56±0.06***

PUFA n-3 24.31±0.07 23.99±1.09 16.57±0.11*** 9.26±1.08*** 3.40±0.16***

PUFA n-6 2.92±0.17 4.64±0.34*** 8.47±0.33*** 12.00±0.92*** 16.19±0.28***

Values are presented by mean ± SD of ten replicates.

Values in a row that does not share the same letter(s) are

significantly different at p < 0.05.

Nutritional quality indices
The NQIs are listed in Table 3. After freezing, a significant

decrease in the n-3/n-6 ratio was observed (Table 3). This ratio
decreased by 97.48% after 90 days of storage. The PUFA/SFA
ratio decreased significantly during freezing (p < 0.05). Sim-
ilarly, EPA + DHA decreased significantly during storage and
reached its lowest value after 90 days (1.17) compared to fresh
crabs (10.81). The polyene index (PI), used as a marker of oxida-
tive rancidity of crab meat, also decreased during freezing (p <
0.05) (Table 3). However, the indices of atherogenicity (AI) and
thrombogenicity (TI) significantly increased by 385.33% and
818.66%, respectively, in frozen crab after 90 days of storage.
Hypercholesterol ratio (h/H) decreased significantly (p < 0.05)
by 59.73% in frozen crabs after 90 days compared to raw crabs
(Table 3).

Lipid peroxidation
The results of lipid peroxidation are shown in Figure 3. This

phenomenon increased significantly during the storage period,
as TBARS and PV levels reached their highest values after 90
days of storage compared to fresh crabs (Figure 3).

Figure 3. Lipid peroxydation indices in raw and frozen crabs.

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Ghribi et al., 2023 Comparison of lipid content and fatty acid profile of fresh and frozen blue swimming crab Portunus Segnis

Table 3. Nutritional quality indices of fresh and frozen crab’s meat after 15, 30,

60 and 90 days of frozen storage.

Indices Fresh 15 days 30 days 60 days 90 days

n−3
n−6 8.35±0.51 5.18±0.28*** 0.95±0.05*** 0.78±0.11*** 0.21±0.01***

PUFA
S FA 1.64±0.02 1.33±0.14 0.95±0.05*** 0.56±0.03*** 0.40±0.01***

EPA+DHA 10.81±0.13 10.38±0.44*** 5.76±0.64*** 3.50±0.77*** 1.17±0.03***

PI 1.72±0.09 1.35±0.16*** 0.66±0.03*** 0.38±0.10*** 0.12±0.01***

AI 0.36±0.01 0.47±0.07*** 0.71±0.03*** 1.16±0.04*** 1.65±0.06***

TI 0.12±0.01 0.15±0.02*** 0.25±0.01*** 0.50±0.03*** 1.10±0.08***

h
H 2.98±0.10 2.42±0.31*** 1.82±0.18*** 1.39±0.15*** 1.20±0.05***

Values are presented by mean ± SD of ten replicates.
Values in a row that does not share the same letter(s)
are significantly different at p < 0.05.

Figure 4. PCA Analysis - PCA analysis showing separation between fresh and

frozen blue crab groups

Principal component analysis (PCA)
The PCA revealed a two-dimensional pattern that explained

85.3% of the total variance, including factor 1 (71.7%) and fac-
tor 2 (13.6%), and mainly showed the difference between raw
and frozen individuals (Figure 4). The fresh crabs were charac-
terized by higher contents and amounts of TL, MUFA, PUFA,
PUFA/SFA, EPA + DHA, n-3/n-6, and h/H. The group of 15
days frozen crabs was the closest to the raw group. The 90-day
frozen crab group had high values for SFA, PUFA n-6, TBARS,
PV, AI, and TI (Figure 4). PCA analysis performed for all mea-
sured parameters highlighted the clear separation between the
experimental groups during the freezing process.

Discussion
Crab species are considered a good source of lipids, pro-

teins, essential elements, and vitamins beneficial for maintain-
ing human health [19]. However, inadequate preservation of
seafood could result in a significant loss of their nutritional qual-
ity. Freezing is the most popular form of food preservation (e.g.,
chicken, fish, beef, etc.). This process is known to preserve food
quality by reducing the deterioration of color, flavor, and texture
over time and limiting the degradation process caused by mi-

croorganism activity [20]. In the present study, total lipids (TL)
in blue crab meat decreased significantly over time during stor-
age at −18◦C. This lipid degradation could be responsible for
the shortening of the shelf life of the marine product due to the
oxidation of unsaturated fatty acids (UFA). However, Benjakul
et al., [21] reported that catalysts released from denatured or de-
stroyed muscle cells of marine products can accelerate lipid ox-
idation. The current results are consistent with the work of [22]
on the mussel (Perna canaliculus) from New Zealand. The vari-
ations in lipid content in frozen samples could be related to lipid
oxidation. Our results are in agreement with the work of [23],
who confirmed that the decrease in TL content in the meat of
frozen catfish was due to oxidation. [24] reported that the lipid
content in the muscle of four fish species (Mugilidae, Sparidae,
Sciaenidae, and Platycephalidae) decreased significantly during
the freezing process.

The predominant fatty acids (FA) in fresh crab meat were
palmitic acid, oleic acid, EPA, and DHA fatty acids. When the
crab meat was frozen at −18◦C, the FA composition changed in
their proportions; SFA increased, while MUFA and PUFA de-
creased significantly. Similar results on the changes of PUFA,
MUFA, and SFA during freezing were observed in fish [10]. The
reduction in PUFA content is likely due to oxidative reactions
that occurred during the freezing process. It should be noted
that the high degree of unsaturation favors the oxidation of PU-
FAs [25]. The n-3 PUFAs such as EPA and DHA were signif-
icantly reduced. In contrast, arachidonic acid (AA), which is
known as a pro-inflammatory lipid compound, increased upon
freezing. The results showed that the polyene index (PI) and
the sum of DHA + EPA decreased due to the reduction of EPA
and DHA, reflecting the degradation of PUFA, as previously re-
ported by [26] in frozen hake. The n-3/n-6 index is considered
a good standard for comparing fish oil quality [27]. A ratio of
1:1 or 1:5 could be beneficial for human health [28]. Our results
showed that the n-3/n-6 ratio decreased after freezing, indicating
a significant loss in the nutritional quality of the crab meat, but
it was higher than the values recommended by the World Health
Organization (WHO) up to 60 days of storage [29]. The same
trend was observed for PUFA/SFA ratio. The reduction in PUFA
resulted in a significant decrease in this index, confirming that
frozen crabs are no longer a good source of PUFA. However, up
to a storage period of 60 days, this ratio remained higher (0.45)
than the minimum value recommended by HMSO (1994) for
a healthy human diet. Similar results were observed in frozen
fish at −18◦C [30]. In this study, the h/H ratio decreased sig-
nificantly, indicating a deterioration in meat quality, as higher
values are considered healthier for humans [31]. Atherogenic
(AI) and thrombogenic (TI) indices are commonly used to deter-
mine how healthy the fat content of the food in question is [32].
These indices increased, possibly due to the loss of beneficial FA
and the enhancement of atherogenic FA. Others reported similar
results in rainbow trout frozen at −15◦C for 3 months [33].

The observed changes in the main FA showed that they were

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Ghribi et al., 2023 Comparison of lipid content and fatty acid profile of fresh and frozen blue swimming crab Portunus Segnis

involved in the oxidation process. The freezing temperature
used was able to significantly increase PV and TBARS levels in
frozen crab meat. The appearance of radicals and the formation
of hydroperoxides can lead to oxidative changes [34]. The oxida-
tion of lipids in seafood can produce a rancid taste and odor that
compromises the nutritional value and safety of seafood through
the formation of primary oxidation products that rapidly con-
vert to secondary products [35]. The increase in PV, which is
commonly used as an index to quantify the amount of hydroper-
oxide indicating oxidative deterioration [36], showed the devel-
opment of rancidity, off-flavor, color, and nutritional deteriora-
tion in frozen crab meat. Our results confirm previous work on
frozen fish and shrimp [37]. The higher increase in TBARS,
known as secondary lipid oxidation products, during frozen stor-
age suggests a high rate of lipid oxidation and decay. Similar re-
sults were observed in frozen silver catfish [38] and pink salmon
[39].

From the above results, we can conclude that prolonged stor-
age at −18◦C leads to a loss of nutritional quality of crab meat
due to the formation of oxidation products and contributes to
the acceleration of lipid degradation. According to this study,
shorter storage of no more than 15 days at −18◦C is strongly
recommended when crabs are frozen at this temperature.

Conclusion
The freeze had significant effects on the biochemical com-

position of the crabs. Major changes were observed in the FA
profile and Nutritional Quality Indices (NQI) of frozen crabs.
As with other seafood, the nutritional quality of crab species can
be affected by frozen storage. The deterioration of flesh qual-
ity of frozen crabs increased with the duration of freezing, as
shown by the elevated Peroxide Value (PV) and Thiobarbituric
Acid Reactive Substances (TBARS) values. It can be concluded
that blue crabs stored at −18◦C are still a good source of fatty
acids, especially omega-3, after a reasonable period of time. Our
study concerns local consumers of this crab and, in particular,
restaurants and hotels that use this product on their menus. We
recommend that consumers of this product gain a deeper under-
standing of the potential hazards and advantages related to the
freezing methods employed.

Acknowledgments
We would like to thank Mr. Hassen Mejri for his technical

assistance.

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	Abstract
	Introduction
	Material and methods
	Sampling Site
	Preparation of the Samples
	Lipid Content
	Fatty Acid Profile
	Nutritional Quality Indices (NQI)
	Lipid Peroxidation
	Statistical Analysis

	Results
	Lipid content
	FA composition
	Nutritional quality indices
	Lipid peroxidation
	Principal component analysis (PCA)

	Discussion
	Conclusion

