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Nutritional evaluation in five species of tuna

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Proximate composition was determined in different body parts (skin, white muscle, red muscle, head muscle and belly flap) of five species of tuna; Katsuwonus pelamis (skipjack, balaya,) , Thunnus albacares (yellow fin tuna, kellawalla), Auxis rochei (Bullet, tuna, ragoduwa), Auxis thazard (frigate tuna, alagoduwa) and Euthynnus affinis (kawakawa, attawalla.) obtained from the Negombo fish landing site. Fatty acid profiles were also analyzed in the skin, red and white muscle of the five species. No significant differences between the tuna species were observed with respect to protein, total fat, and moisture contents. The ash content in Frigate tuna and Kawakawa were significantly higher than the other species. The muscle tissue in all the species was rich in protein (20-25%) and low in fat «2%). The skin of all the species recorded high protein (27-32%) and lipid (6-8%) levels. The moisture content was low in the skin compared to the other tissues. All five species of tuna studied here recorded less SFA (11-33%) and more PUF A (50-74%) in the muscle tissues. The MUF A content in muscle tissue ranged from 8-25% and all the species contained both EPA (eicosapentaenoic acid, C20:5n-3) (2-19.7%) and DHA (docosahexaenoic acid, C22:6n-3) (4-42%) in varying amounts.
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Nutritional evaluation in five species of tuna
K.A.A. U.
Karunarathna
and M V.E. Attygalle
Department of Zoology, University of Sri Jayewardenepura,
Nugegoda, Sri Lanka
Received on - 20 - 10 - 2009
Accepted on -
13 - 11 -
2009
Abstract
Proximate composition was determined in different body parts (skin, white
muscle, red muscle, head muscle and belly flap) of five species of tuna;
Katsuwonus pelamis (skipjack, balaya,) , Thunnus albacares (yellow fin tuna,
kellawalla), Auxis rochei (Bullet, tuna, ragoduwa), Auxis thazard (frigate
tuna, alagoduwa) and Euthynnus affinis (kawakawa, attawalla.) obtained
from the Negombo fish landing site. Fatty acid profiles were also analyzed in
the skin, red and white muscle of the five species. No significant differences
between the tuna species were observed with respect to protein, total fat, and
moisture contents. The ash content in Frigate tuna and Kawakawa were
significantly higher than the other species. The muscle tissue in all the
species was rich in protein (20-25%) and low in fat «2%). The skin of all the
species recorded high protein (27-32%) and lipid (6-8%) levels. The moisture
content was low in the skin compared to the other tissues. All five species of
tuna studied here recorded less SFA (11-33%) and more PUF A (50-74%) in
the muscle tissues. The MUF A content in muscle tissue ranged from 8-25%
and all the species contained both EPA (eicosapentaenoic acid, C20:5n-3) (2-
19.7%) and DHA (docosahexaenoic acid, C22:6n-3) (4-42%) in varying
amounts.
Key words: Tuna, proximate composition, n-3 fatty acids, n-6 fatty acids,
EPA,DHA
Introduction
Nutrition has been cited as one of the primary reasons why consumers are
attracted to seafood (Gall et al, 1983). They also provide a good balance of
proteins, lipids, vitamins and minerals ( Edirisinghe et al, 2000). Edible fish
muscle normally contains about 18% protein, 1-2% ash and the balance 80%
of the wet weight of muscle is made up of lipid and water (Ackman, 1995).
Like most animal foods, seafood proteins have excellent nutritive value. Fish
protein contains all the essential amino acids and it is highly digestible.
(Jhaveri et ai, 1984). In terms of nutritive value, fish protein ranks above
7
Karunarathna and Aff.vgallc
casein (Haard 1995; Snook, 1984). Fish is the chief source of animal protein
in the cereal-based diet of Sri Lankans (Nathanael et al, 1997).
Lipids have been considered as a key energy source for growth metabolism,
visceral organs and muscle functions. But now, marine lipids are receiving
increasing attention as a source of C20 and C22 carbon omega 3 polyenoil
fatty acids which have profound implications for health and disease (Uauy-
dagach and Valenzuela, 1992).
The unique feature that differentiates lipids of marine species from those of
land animals is the presence of long chain PUF A, namely eicosapentaenoic
acid (EPA C20:5 w-3), docosahexaenoic acid (DHA C22:6 w-3) and to a
lesser extent, docosapentaenoic acid (DPA C22:5 w-3) (Shahidi, 1998),
which are important in the prevention and treatment of cardiovascular
diseases, hypertension, arthritis, other inflammatory and autoimmune
disorders, and cancers (Jones, 2002).
Anatomical position of the flesh sampled is an important factor because
nutrients are not distributed evenly in all the body parts of the fish. Lipid
content has been found to vary from 2% to almost 30% depending on the area
of the body being sampled (Porter, 1992). Red or blood meat has been found
to contain more fat and less protein than white meat (Geiger. and Borgstrom,
1962). The major portion of minerals in the fish body is distributed in skeletal
tissues. Generally most of the bones and other skeletal tissues of fish are
removed prior to consumption.
Tunas are among the largest, most specialized and commercially important of
all fishes. Belonging to the genus Thunnus of the family Scombridae, they
are found in temperate and tropical oceans around the world and account for
a major proportion of the world fishery products (Lee et aI, 2005).
In the present study, moisture, ash, total fat, and protein contents of five
species of tunas namely; Katsuwonus pelamis (skipjack, balaya,) , Thunnus
albacares (yellow fin tuna, kellawalla), Auxis rochei (Bullet, tuna,
ragoduwa), Auxis thazard (frigate tuna, alagoduwa) and Euthynnus affinis
(kawakawa, attawalla,) were determined in different body parts (skin, red
muscle, white muscle, head muscle and belly flap) and the fatty acid profiles
of the skin, red muscle and white muscle of these five species of tuna were
also determined.
Sample size and the average size (Fork length) of the fish are given in
table 1.
8
Nutritional Evaluation
(!(fUlIG
Materials and Methods
Fresh fish samples purchased from Pitipana, Negombo fish landing site were
packed in ice and transported to the laboratory from July 2006 to April 2008.
Samples of skin, belly flap, red, white and head muscles were separated to
determine moisture, ash, total fat, and protein contents in each species
respectively. Moisture content was determined by oven drying at 105 DCand
the ash content of each sample was determined by using the muffle furnace at
550DC.Total fat and protein contents were determined by Majonnier method
and Kjeldhal method respectively (Kirk and Sawyer, 1991). Then oils were
extracted from the Bligh and Dyer method and the Fatty Acid Methyl Esters
(FAMEs) were prepared by sodium methoxide method. The methyl esters of
each fatty acid were then analyzed by Gas chromatography (Agilent, 4890 D,
Innowax,) (Temperature; injector 270°C and detector 250°C, the oven was
first maintained at 170°C and then programmed to225°C at the rate of
1°C/minute) The chromatographic peaks were then identified by comparison
of the retention time with cod liver oil as standard and GLC 411 as internal
standard. Percentages of each fatty acid was calculated as a percentage of
FAMEs. Statistical differences between species and within species were
determined at 5% level using One-Way variance of analysis (ANOVA)
Minitab version 14.
Results and Discussion
From table 1 it is observed that the highest constituent in all the samples was
moisture. The average moisture content did not vary significantly between
the tuna species. The skin contained significantly (p<0.05) less moisture (58-
60%) compared to the other body parts which contained between 69- 74%.
Edirisinghe et al (2000) had reported higher values (69-80%) for of moisture
content of some marine fish. Jayasinghe (1996) reported values for fresh
water species in the range of 60-84%.
No significant differences in the average protein content were observed
between the species. But the protein content of the skin was significantly
higher (p<0.05) than the other body parts in all the tuna species (Table 1) and
ranged from 27-32%. The protein content in the red muscle, white muscle
and head muscle were 20-25%, 20-23% and 20-25% respectively. There were
no significant differences in the protein contents among red, white and head
muscles. According to Sidwell (1981) the belly flap recorded significantly
low amount of protein (16-17%) than the other body parts. Most fin fish
muscle contains about 18-22% protein and the average for 540 analyses made
was 18.5±3.6%. In the present study protein values recorded for the tuna
species are higher than this average. Suzuki (1981) has reported that within
9
Karunarathna and Anvgallc
species, white flesh has more protein than dark flesh. In the present study no
significant difference in protein content was evident in the white and red
muscle of tuna.
Kawakawa and Frigate tuna recorded significantly higher (p<0.05) amount of
ash compared to the other species (Table 1). These two species also recorded
significantly much higher contents of ash in their skins than the other tissues
studied. In most fish the average ash content in the edible muscle portion has
been found to range between 0.5 to 1.8% of wet weight (Sidwell, 1981). In
the present study the ash content in muscle and belly flap varied between 0.4
to 1.2%, which is similar to the values reported by Sidwell (1981) for the
edible muscle portion.
There was no significant difference in total fat content among the different
species of tuna (Table 1). The percentage of total fat in the skin of all tunas
was significantly higher (p<0.05) than in the other body parts. In the skin
total fat varied from 6-9% and in the other body parts it was less than 2%.
The total fat content in the red muscle, white muscle, head muscle and belly
flap ranged from 1-1.3%, 0.6-0.9%, 0.7-1.5% and 0.9-1.3% respectively.
There is considerable variation in the distribution of fat in different tissues.
The belly flap of Salmon has been reported to contain 30-50% fat (Ackman,
1995). The Indian oil Sardine (Sadinella longicepsi has been reported to have
27% or more lipid in the skin and only 6% in the muscles (Nair et al,1979).
In the capelin (Mallotus villosus) the highest amount of fat (35%) was found
in the belly flap, followed by the skin (25%). In the mackerel the Skin
contained most fat followed by the white muscle. In all tunas investigated
here the skin recorded the highest amount of fat compared to the other
tissues.
10
Nutritional Evaluation of tuna
Table 1. Proximate Composition in the different body parts of five species of
tuna ( n>20, mean
±
SD)
Skipjack Yellow fin Frigate
Fish Type tuna tuna tuna Bullet tuna Kawakawa
Number of
Samples 29 26 28 22 27
Fork Length 49.50± 1.8 52.00±2.1 47.20± 1.6 45.00± 1.7 25.50 ± 2.3
Skin 59.60±1.61 58.13±3A3 58.19±1.87 58.65±2.39 58.19±1.87
Red 71.60±1.05 70.83±0.70 71.39± lA5 70.68±1.l5 72.77±lA5
~White 72.05±1.20 72A4±IAl 73.00±1.14 71.06±1.03 73Al±IA2
=
a.
••
Head 71.83±1.38 71.93±0.71 73Al±2.80 69.86±2.74 73.73±1.42
=
.-
'"
Belly
~flap 71.97±0.78 70.53±0.76 71.67±IA9 68.60±1.89 71.02±0.77
Skin 28.31± 0.53 27.12±0.5 31.67±0.38 32.67±OA2 30.06±OA2
~20.22± 25.35±
e
Red 24.53± 0.24 0.19 0.21 21.95±0.31 21A2±OAO
.-
I:
a.
.-
White 23.79±0.38 21A2±0.25 23.92±OA3 23.37±OAl 20.73±0.29
I:
0
C.i
I:
Head 20A8±0.85 20.98±0.34 24.83±OA1 25.6±0.26 20.7±0.39
·as
Belly
.-
0
••
flap 16.04±0.24 16.94±0.67 19.74±0.18 17A7±0.23 16.85±OA2
Q.,
Skin 7A5±1.34 8.87±1.23 8.92±1.03 6.71±l.23 6.31±1.l2
Red
~muscle 0.98±0.23 1.01±0.23 l.08±0.77 0.99±0.23 1.26±OA3
=
.-
White
~Muscle 0.77±0.23 0.88±0.25 0.75±0.12 0.68±0.54 0.60±0.14
-;
.-
0
Head 0.72±0.17 0.98±0.13 1.54±0.13 1.21±0.12 0.67±0.32
~Belly
flap 1.34±OA2 0.90±0.16 0.99±0.12 0.88±0.37 1.26±0.21
Skin 1.33±0.98 1.03±OA5 3.21±2.27 0.98±0.63 6.06±0.98
Red
muscle 1.09±0.22 0.92±0.21 0.73±0.12 1.19±0.17 0.90±0.36
~White
=
-=
Muscle 1.02±0.10 1.12±0.15 0.79±0.35 0.71±0AO 1.03±0.04
'"
<Head 0.88±0.07 1.00±0.06 OAO±0.28 0.69±0.70 0.65±OA6
Belly
flap 0.58±0.12 0.67±0.38 1.03±0.59 0.78±0.34 0.92±0.59
11
Katunarathna and AHygallc
In all the tuna species studied here the skin recorded the highest amounts of
protein, total fat and ash (only in 2 species), compared to the other body
parts. Therefore if the skin is not consumed valuable nutrients may be lost
with it. In the smaller species of tuna such as Bullet tuna (Ragoduwa), Frigate
tuna (Alagoduwa) and Kawakawa (Attawalla) the skin is not as tough as in
Yellow fin tuna, and may be consumed with the flesh.
Fatty acid profiles of the skin and muscle for the five species of tuna are
given in table 2. In the present study significant differences (p<0.05) between
the total saturated fatty acids and unsaturated fatty acids were observed
within the species. Total saturated fatty acids (SF A) in the muscle tissue (red
and white muscle) of the tunas were low and varied between 11% (skipjack,
white muscle) to 33% (skipjack, red muscle). Total polyunsaturated fatty
acids (PUF A) in the muscle tissues of all species of tuna were high and
ranged between 50% (frigate tuna, red muscle) to 74% (kawakawa, red
muscle). Total monounsaturated fatty acids in the muscle tissues of tunas
were also low and varied between 8% (skipjack tuna, red muscle) and 25%
(yellow fin tuna, white muscle).
Table 2.
Percentage of saturated fatty acids (SFA), MUF A (Monounsaturated
Fatty acids) and PUFA (Poly unsaturated fatty acids) in five species of tuna.
(Mean± SD)
Fish Type Body part SFA MUFA PUFA
Skin 23A7±0.90 24.57±1.61 51.27±1.40
Skipjack White 10.92±1.44 21.05±lAl 68.05±1.99
Red 33.11±2.57 7.52±1.14 59.36±1.89
Skin 18.18±1.01 36.53±2.53 45.02±1.93
Kawakawa White 26.64±1.62 10.71±1.21 61.92±1.88
Red 13.91±1.98 11.85±0.78 73.94±2.83
Yellow fin Skin 33.77±1.63 11.61±1.01 53.33±2.19
White 12.30±1.52 14.l1±0.93 72.36±2.56
tuna Red 22.74±lA6 21.11±0.94 55.85±1.78
Skin 13.65±l.46 1O.67±1.09 75.69±3.32
Bullet tuna White 17.58±1.63 25A4±1.07 56.01±1.95
Red 21.31±1.35 11AO±0.75 64.06±2.09
Skin 26.35±2.52 34.93± lA3 38.73±1.62
Frigate tuna White 24.92±1.80 22.02±1.07 53.05±2.13
Red 21.33±1.46 20.81±1.15 49.91±1.78
12
Nutritional Evaluation of tuna
Total SFA, MUFA, and PUFA levels in herring (Clupea harrengus) from
USA were found to be 26%, 47% and 27% respectively (Ackman, 1995). In
fresh water carp (Cyprinus carpio) from Turkey the corresponding values
were 36%, 32% and 32% (Donmez, 2009) respectively. Tunas in this study
were characterized by high levels of PUF A, while in herring higher
concentrations of MUF A were found. Carp was characterized by sightly
higher concentrations of SFA over MUF A and PUF A. In little tuna
(Euthunnus alletteratus) from the Mediterranean similar results to the tunas
in this study were reported, as the major fatty acid class was PUF A followed
by SFA and MUF A (Selmi et aI, 2008)
Table 3. PUF A/SF A ratio for five species of tuna
Fish Type SFA% PUFA% PUF A/SF A/ratio
White Red Skin White Red Skin White Red Skin
Skip jack 10.92 33.11 23.47 68.05 59.36 5l.27 6.23 1.79 2.18
Kawakawa 26.64 13.91 18.18 6l.92 73.94 45.02 2.32 5.32 2.47
Yellow fin tuna 12.3 22.74 33.77 72.36 55.85 53.33 5.88 2.46 l.58
Bullet tuna 17.58 21.31 13.65 56.01 64.06 75.69 3.19 3.01 5.55
Frigate tuna 24.92 21.33 26.35 53.05 49.91 38.72 2.13 2.34 1.46
The total SFA, MUF A and PUF A in the skin of the tunas varied between
13.65 - 33.77%, 10.67 - 36.53% and 38.75 to 75.69% respectively. The ratio
of PUFAlSF A for white and red muscle of the five species of tuna is given in
table 3. A minimum value for PUFAISFA ratio recommended by nutritionists
is 0.45. From table 3 it is seen that for the tuna species investigated here.
PUFAISfA ratio varied between 1.79 and 6.23, which was well above the
recommended minimum value.
Table 4. Ratio of n6/n3 fatty acids for five species of tuna
Species Total n-6 Fatty acids Total n-3 Fatty acids n6/n3 ratio
White Red Skin White Red Skin White Red Skin
Skip jack 15.47 15.31 18.87 57.45 60.51 45.42 0.27 0.25 0.42
Kawaka 2l.27 37.97 26.38 53.20 40.11 31.09 0.40 0.95 0.85
wa
Yellow 20.77 1.30 16.7 61.09 44.77 48.19 0.34 0.03 0.35
fin tuna
Bullet 21.73 41.46 18.31 48.38 35.29 56.51 0.45 l.l7 0.32
tuna
Frigate 36.46 26.70 46.51 25.60 40.19 12.08 1.42 0.66 3.85
tuna
13
The n6/n3 fatty acid ratio for white and red muscle of the five species of tuna
is given in table 4. Nutritionists believe that the desirable n6/n3 fatty acid
. ratio should be 5 at a maximum. The
n6/n3
ratios in both white and red
muscle of the five species of tuna investigated here were found to be between
0.03 and 1.42 which was well below the recommended maximum value of 5.
60,--------------------------------------------
50+_------------------------r------------------
~
~40+-----------------------~.------------------
;30+-----------------------~~--------~r_-----
~ 20
+_...--------r-,+,,------------.--..----'f--fIl}-;td::--±-------flI'l--------.lr
t
10 +-1l[i--,rHa--1
h-----~i___Tm__"'fM1___l.l.;Irb--m--t
~ O~_T~~~~~=T~~~~~~~~~~~~~~~
"-
Skipjack
Kawakawa Yellow tin tuna Bullet tuna Ftig
at c tun a
o
EPA
m
OHA
Figure
I. EPA and DHA in skin, red and white flesh of five species of
Figure 1 shows the distribution of EPA (eicosapentaenoic acid, C20:5n-3)
and DHA (docosahexaenoic acid, C22:6n-3) which are considered as
beneficial fatty acids in health care, especially coronary heart diseases. The
highest DHA value (42%) and the lowest EPA value (2.4%) were recorded in
the red muscle of yellow fin tuna. The highest EPA and value (19.73%) was
recorded in the red muscle of skipjack tuna. The sum of EPA and DHA in the
muscle tissue of the tunas ranged from 16% (frigate tuna, white muscle) to
44% (yellow fin tuna, red muscle). Therefore these tuna species can be
considered as good source of these fatty acids. Reena
et
at
(1994) report that
the Indian fish they evaluated were excellent source of EPA and DHA as the
major constituent of PUF A were these two fatty acids.Although the muscle
tissue of the tuna species contain low levels of fat (2%) they have desirable
fatty acid profiles which can contribute to good health.
Acknowledgements
Authors acknowledge financial support by University of Sri Jayawardenapura
research grant No. ASP/61R12006/08
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16
... The muscle tissue of tuna was rich in protein (20%-25%) and low in fat (< 2%) (Karunarathna & Attygalle, 2012). Many studies on tuna focus on the protein components of tuna (Jiang et al., 2019;Yu et al., 2021), few were undertake about the lipid components despite its great important physiological actions. ...
Article
A method of ultrahigh performance liquid chromatography coupled to high resolution mass spectrometry (UPLC-HRMS) was established for characterization of the lipid profile of Skipjack tuna. Over 300 lipid molecular species were identified through cross-acquisition in both positive and negative ion mode. Phospholipids (PLs) were dominant in Skipjack tuna. Lysophosphatidylethanolamine (LPE), phosphatidylethanolamine (PE), lysophosphatidylcholine (LPC) and phosphatidylcholine (PC) were the main lipid molecular species in PLs, accounting for 89.24% of the total PLs. The ratio of sphingolipids (SLs) and glycerolipids (GLs) were considerable, accounting for 12.30% and 13.60% of the total lipids respectively. Ceramide (Cer) was the main lipid molecular species of SLs, accounting for 64.96% of total SLs, followed by sphingomyelin (SM), accounting for 25.45% of total SLs. Ether diglycerides (ether DG) were the main lipid molecular species of GLs (97.83%). The main fatty acids (FAs) are unsaturated fatty acids (UFAs) in Skipjack tuna. Besides, a new FAs class branched fatty acid esters of hydroxy fatty acids (FAHFA) was detected, together with the FA. The active lipids identified in this study can be used to evaluate the nutritional value of Skipjack tuna.
... The average protein content in the skin from various tuna species is known to range between 20.54-36.09%, varying with species, age, size, and environmental conditions [44,45]. Considering that around 80% of total fish skin protein is comprised of collagen, the 16.6% yield obtained from the PSC skin extraction represents a high percentage of the maximum potential yield [46]. Certainly, the intense feeding program to which farmed tuna are subjected within a restricted environment probably contributed to the overall high isolation values reported in this study. ...
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At the behest of the Green Deal, circular economy concepts are currently being widely promoted, not least within the aquaculture sector. The current study aims to demonstrate the technical feasibility of extracting collagen and fish oils from waste Atlantic bluefin tuna biomass originating from the Maltese aquaculture industry. For collagen, a three-stage methodology, consisting of pre-treatment, extraction, and retrieval, was applied to biomass originating from bone, skin, muscle, and internal organs (offal) in order to extract both acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC). The chemical identity of the extracted collagen was confirmed through the conduction of hydroxyproline and SDS-PAGE tests as well as through FTIR, whilst the extracted collagen was also tested for its microbiological and heavy metal profiles. The collagen yield was found to be highest for skin tissue and for PSC-based protocols and is comparable to the yield cited in the literature for other tuna species. Oils were extracted through low temperature, high temperature, and enzymatic means. The fatty acid profile of the extracted oils was assessed using GC-FID; this indicated high proportions of EPA and DHA. Yield indicated that the enzymatic extraction of oil is most effective. High heat and the presence of iron-containing muscle starting material promote oxidation and rancidity. Further effort into the optimization of both collagen and lipid extraction protocols must be invested, with a special focus on the production of high-value fractions that are much closer to the quality required for human use/consumption.
... These values were generally consistent with ranges reported for other fish species and seafood [ 2 , 39 , 45 ]. The fillets of fish species which is preferentially consumed in the Nigeria, and analysed in this study have been reported to contain high levels of potassium, calcium, zinc, and magnesium [46] . Also higher concentrations of calcium, iron, and zinc have been detected in the muscle tissues of species from tropical thermal regimes such as Nigeria [47] . ...
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Global concern for good health and well-being of human populations especially in underdeveloped and developing nations has necessitated the need for routine nutritional assessment of food sources. This study was undertaken to determine the nutrient composition of commonly consumed freshwater fish species in Ikpoba reservoir and to assess the potential contribution of selected key nutrients in the fishes to recommended nutrient intakes (RNIs). Proximate composition of Clarias gariepinus and Tilapia zillii showed moisture content of 61.09% and 63.39 %; protein value of 15.15 % and 15.71%; lipid value of 6.03% and 1.48 %; and ash content of 4.58 % and 5.09 % respectively. Mineral content of fish species ranged from 3.32 to 5.64 mg/100g (sodium); 8.14 to 12.64 mg/100g (potassium); 2.56 to 4.42 mg/100g (magnesium); 1.75 to 5.85 mg/100g (calcium); 5.47 to 9.35 mg/100g (iron) and 1.40 to 3.66 mg/100g (zinc). Potential contribution to RNIs for preschool children and adults indicated that Clarias gariepinus and Tilapia zillii contributed ≥25% of RNIs for iron (38.71% and 44.57%) and zinc (38.33% and 25.67%) for preschool children. This study has increased the knowledge on the contribution of fishes to RNI in combating nutritional deficiencies in Nigeria.
... Foodstuffs are suggested to have the highest quality when the values of AI and TI are relatively lower [21]. In other words, the values of AI and TI are taken to determine the lipid quality of foodstuffs including fish and other fishery products [7,8,14]. The AI value describes the relation between the number of main saturated fatty acids and unsaturated acids, which are known as pro-atherogenic and anti-atherogenic, respectively. ...
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... The importance of minimising plate waste was also accentuated in a Sri Lankan study from 2012, where five species of tuna (amongst them Auxis thazard, also included in this paper) were analysed for several nutrients. According to the results, the skin of all sampled species of tuna contained the highest levels of potassium, calcium, zinc, and magnesium, and the authors concluded with the importance of consuming various parts of the fish to reap the most nutritional benefits (Karunarathna and Attygalle, 2012). Furthermore, a 60 % loss of total iron in the Cambodian SIS, E. longimanus, was reported when the head and viscera were removed, which implies that populations that are prone to iron deficiency, such as women of reproductive age, could be optimising their use of locally available nutrient-dense foods (Roos et al., 2007a). ...
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Fish is an important part of the Sri Lankan diet. However, existing data on the nutrient composition of fish in Sri Lanka is highly outdated and limited. The aim of this study was to report the nutrient composition of commonly consumed marine fish species in Sri Lanka and assess the potential contribution of selected key nutrients in fish to recommended nutrient intakes (RNI). Fish were sampled during a survey with research vessel Dr. Fridtjof Nansen around Sri Lanka. Species were categorised as either small (<25 cm, n = 12) or large (>25 cm, n = 7), and three composite samples from each species were analysed using accredited methods. Small species commonly consumed whole contained significantly higher concentrations of micronutrients such as calcium (960 mg/100 g), iron (3.3 mg/100 g), zinc (2.1 mg/100 g), vitamin A (295 µg/100 g), and EPA and DHA (0.14 and 0.32 g/100 g, respectively) than larger species where only the fillet is consumed. Several species were identified to contribute ≥25% of the RNI of women of reproductive age for multiple essential nutrients. These data may represent an important contribution to the future development of the Sri Lankan food composition database.
... According to the results, the skin of all species of tuna contained the highest levels of potassium, calcium, zinc, and magnesium, and they therefore concluded with the importance of consuming various parts of the fish to reap the most nutritional benefits (122). ...
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This is the MSc Thesis carried out by Amalie Moxness a student at the UIB, under the supervision of Dr. Marian K and I was helping with them to get the species name and other data during the NANSEN Cruise.
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Millions of people eat fish around the globe, which is high in omega-3 fatty acids and a rich source of protein. Fish is typically processed with a variety of processing techniques. Processing can have an impact on the nutritional value of fish. The effects of processing on proximate composition and sensory quality parameters were investigated. According to the results obtained, the mean moisture, fat, and ash contents of raw fish were found to be 71.36±0.30 %, 0.96±0.02 %, and 1.95±0.05 % respectively. The moisture, ash, and fat contents were found to differ significantly (p<0.05) depending on the processing. The highest and the lowest moisture contents were found to be recorded in raw (71.36±0.30 %) and fried samples (41.01±1.77 %). The highest (4.79±0.24 %) and the lowest (1.77±0.06 %) ash contents were found to be recorded in fried and grilled samples. The highest (8.78±0.96 %) and the lowest (0.96±0.02 %) fat contents were found to be recorded in fried and raw samples. Evaluation of sensory quality parameters was performed with nine hedonic scales on both samples. It showed that frying and boiling achieved the highest ratings, while steaming was the least. For nutritional value, boiling was found to be the best. Frying obtained the highest while steaming obtained the least score. Out of the total population, a greater portion consumes tuna fish without the knowledge of the impact of processing on nutritional composition. The findings of this present study will help to explore the best processing method with minimal nutrient loss and to secure maximum palatability.
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INTRODUCTION The different methods of fish processing may result in different waste potential and quality (Bragadottir et al., 2007). Solid waste resulted from tuna fish processing in the form of fish bones, fins, scales, and dark meat of about 20-30% from the total fish was not optimally utilized. Fish dark meat is a meat layer found in the whole fish lower body part under scales, approximately 2-20% depending on the fish species and size, containing myoglobin, hemoglobin and high in fat. Stone (2007) stated that tuna loin processing resulted in waste of approximately 37.1% and dark meat of 17.9%. That waste was not commonly utilized or was merely used for animal feed making, yet in fact fish dark meat has essential components that might be used as nutritional sources in food processing. Karunaratha and Attygalle (2010) stated that tuna dark meat had the moisture content of 70.83%, protein of 20.22%, fat of 1.01%, and ash of 0.92%, besides other compositions, such as SFA of 22.74%, MUFA of 21.11% and PUFA of 55.85%.
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Dry fish block is a food product from by-product of tuna loin. It is salted, liquid smoked, and dried. This study was aimed to determine fatty acid profile of the dry fish block after the addition of liquid smoke. The dry fish block was composed of twelve saturated fatty acids (SFA), six monounsaturated fatty acids (MUFA), and nine polyunsaturated acids (PUFA). The total of SFA in dry fish block without and with liquid smoke was 19.94% and 21.29%, while MUFA was 9.35% and 11.77% and PUFA was 14.45% and 16.04%, respectively.
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We determined the oil content, fatty acid composition, and cholesterol content of common carp (Cyprinus carpio), crucian carp (Carassius carassius), chub (Leusiscus cephalus), and tench (Tinca tinca) by GLC. The saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA) levels were found to be 36.49%, 31.92%, 31.59% in common carp; 32.92%, 32.21%, and 34.87% in crucian carp; 36.19%, 32.91%, and 30.90% in chub; and 32.86%, 30.77%, and 36.37% in tench, respectively. The cholesterol (mg/100 g oil) levels of common carp, crucian carp, chub, and tench were determined by GLC methods as 119 ± 2.64 mg, 170.37 ± 2.36 mg, 94.68 ± 3.13 mg, and 179.84 ± 6.75 mg, respectively. Thus, the cholesterol contents of the analyzed freshwater fish species were low but their PUFA contents and nutritional values were high.
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Fatty acid composition of five species of freshwater fish, three marine fish and seven brackish water fish were determined by GLC. Of the saturated fatty acids C16:0 and C18:0 are found to be the dominant ones with C16:0 accounting for 50-55% of the total saturated acids. Among the monounsaturated fatty acids C16:1 and C18:1 and polyunsaturated fatty acids C18:2, C18:3, C20:4, C20:5 and C22:6 are found to be the important ones. Stinging cat fish contained the highest amount of C16:1 (16.52%). The level of arachidonic acid was fairly high in most of the fish lipids analyzed. The ratio C18:1/C18:2 is higher for marine fish than for the freshwater fish and is fairly constant for each group. The fatty acid composition of brackish water fish do not show any definite pattern.
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