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SEASONAL STUDY OF LIPID COMPOSITION IN
DIFFERENT TISSUES OF THE COMMON OCTOPUS
(Octopus vulgaris)
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Mª Pilar Sieiroa, Santiago P. Aubourgb,* and Francisco Rochaa
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ECOBIOMAR, Institute for Marine Research (IIM-CSIC), Vigo (Spain).
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Seafood Chemistry, Institute for Marine Research (IIM-CSIC), Vigo (Spain).
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* Correspondent: FAX: +34986292762; e-mail: saubourg@iim.csic.es
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Running Title: Lipid composition in octopus
Keywords: Octopus, lipid classes, fatty acids, tissue, season
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SUMMARY
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Seasonal variation of octopus (Octopus vulgaris) lipid composition was investigated
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in four tissues: arm, mantle, ovary and digestive gland. A non-homogeneous fat distribution
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was observed, the digestive gland exhibiting a higher (p<0.05) lipid content than the other
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tissues. The ovary showed a higher (p<0.05) fat content than both muscle tissues reaching
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its highest (p<0.05) value in winter. Neutral lipids –free fatty acids, FFA; triglycerides;
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sterols, ST– exhibited their highest (p<0.05) concentrations in the digestive gland and their
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lowest (p<0.05) values in muscle tissues. The phospholipid (PL) content of ovary was the
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highest (p<0.05) of all tissues analysed, the PL content also being significantly (p<0.05)
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higher in the digestive gland than in arm and mantle. The concentrations of most lipid
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classes (FFA, PL and ST) exhibited a seasonal variation. The fatty acid composition
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showed a remarkable difference between the digestive gland and all other tissues analysed.
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Thus, the digestive gland exhibited higher (p<0.05) contents in monounsaturated fatty acids
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and also lower (p<0.05) contents in both saturated (SFA) and polyunsaturated (PUFA) fatty
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acids. The highest mean values in SFA and PUFA were observed in ovary and muscle
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tissues, respectively. A seasonal effect was observed for SFA and PUFA.
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1. INTRODUCTION
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Seafood products are known to provide high contents of important components for
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the human diet such as nutritional and digestive proteins, lipid-soluble vitamins (A and D,
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namely), microelements (I, F, Ca, Cu, Zn, Fe, Se and others) and highly unsaturated fatty
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acids [1, 2]. Marine lipids are now the subject of a great deal of attention due to their high
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content of ω3 polyunsaturated fatty acids (PUFA), which have shown a positive role in
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preventing certain human diseases [3, 4].
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Marine species have shown wide lipid content variations as a result of endogenous
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and exogenous effects [5, 6]. On one hand, and with respect to the endogenous effects, lipid
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matter has been described to exhibit a heterogeneous distribution throughout the body of
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marine species probably affected by physiological factors. In this sense, previous reports
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have shown wide differences in the fat content of fish [7, 8, 9] and cephalopods [10, 11],
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depending on the tissue investigated. On the other hand, and with respect to the exogenous
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effects, seasonal variation was considered to play a key role on temperature, feeding
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availability and other external factors affecting lipid content in different types of marine
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species [12, 13]. In this sense, an important effect of the seasonal variation on the level of
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lipid damage has been reported in processed marine species [14, 15].
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Common octopus (Octopus vulgaris) is a cephalopod species which has been
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traditionally considered to have world-wide distribution in temperate and tropical regions
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[16]. However, recent ecological studies, based on molecular analyses, have shown that its
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distribution seems to be more restrictive, only covering the Mediterranean Sea, the Eastern
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and Western Atlantic Ocean and some areas in the North-western Pacific Ocean [17]. Such
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aquatic food products are typically commercialised fresh, frozen or dried-salted, both at the
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artisan and industrial scales [18]. Previous compositional analyses on octopus have focused
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only on the investigation of phospholipid [19], collagen [20] and tropomyosin [21].
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However, and due to increasing consumer demand, research scientists are paying more
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attention to this aquatic food product, especially to its growth patterns and to the effects of
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its sexual maturation on biochemical and compositional changes affecting food quality [22,
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23].
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The main goal of the present work was to investigate both the distribution of
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different types of lipid classes and the fatty acid composition in different tissues (mantle,
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arm, ovary and digestive gland) of the common octopus. This study was conducted at
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different times of the year (autumn, winter, spring and summer) to investigate the seasonal
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variation of lipid composition.
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2. MATERIALS AND METHODS
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2.1. Octopus source and sampling
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Female octopus (Octopus vulgaris) specimens (n=39) were obtained at the ship
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unloading in the port. Octopus specimens were caught in winter, spring, summer and
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autumn 2004 in three different fishing banks off the Galician (North-western Spain) coast,
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these were: Cíes Islands, Vigo; Corcubión, Finisterre, and Cedeira. Octopus specimens
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were kept in ice for 8-10 hours, from the catch until arrival to our laboratory. Specimens
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were then prepared for analysis.
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The length of individuals ranged from 73 to 110 cm, while the dorsal mantle length
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range was between 14 and 28 cm. Total body weight ranged from 515 to 3,755 g, while the
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range of eviscerated body weight varied between 413 and 3,221 g. Four different tissues
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were considered for the study: arm (skinned), mantle (skinned), ovary tissue and digestive
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gland. Lipid analyses were carried out separately on each of the four tissues. Each octopus
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specimen was studied independently, therefore nine (n=9; winter) and ten (n=10; spring,
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summer and autumn) independent determinations were accomplished in each season to
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carry out the statistical analysis.
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2.2. Determination of the water and lipid contents
Water content was determined by weight difference of the homogenised tissue (1-2
g) before and after 24 h at 105 ºC. The results were expressed as g water/100 g tissue.
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The lipid fraction was extracted by the Bligh and Dyer [24] method. 10 g and 15 g
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of visceral (ovary and digestive gland) and muscle (arm and mantle) tissues were
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employed, respectively. The results were expressed as g lipid/100 g wet tissue.
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2.3. Analysis of lipid classes
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Lipid classes were determined by different spectrophotometric methods. In each
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case, appropriate portions of total lipids were investigated to guarantee the accuracy of the
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method employed.
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Free fatty acid (FFA) content was determined following the Lowry and Tinsley [25]
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method, which is based on complex formation with cupric acetate-pyridine. In this study,
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benzene was replaced by toluene. The results were expressed as g FFA/100 g wet tissue.
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To measure the triglyceride (TG) content, the lipid extract was first purified by thin
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layer chromatography (20 x 20 cm plates coated with a 0.5 mm layer of silica gel G from
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Merck, Darmstadt, Germany) using a mixture of hexane-ethyl ether-acetic acid (90-10-1, v5
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v-v; two developments) as eluent [26]. Once the TG were purified, the method of Vioque
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and Holman [27] was used for measuring the ester linkage content, according to their
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conversion into hydroxamic acids and further complexion with Fe (III). The results were
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expressed as g TG/100 g wet tissue.
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Total phospholipids (PL) were determined by measuring the organic phosphorus on
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total lipid extracts, according to the Raheja et al. [28] method based on the formation of a
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complex with ammonium molybdate. The results were expressed as g PL/100 g wet tissue.
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Total sterols (ST) were determined in total lipid extracts by the method of Huang et
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al. [29] based on the Liebermann-Buchardt reaction. The results were expressed as g
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ST/100 g wet tissue.
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2.4. Fatty acid analysis
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Total lipid extracts were converted into fatty acid methyl esters (FAME) according
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to the Lepage and Roy [30] method. FAME were analysed by GC (Perkin-Elmer 8700
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chromatograph) employing a fused silica capillary column SP-2330 (0.25 mm i.d. x 30 m,
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Supelco Inc., Bellefonte, PA, USA) according to Aubourg et al. [31]. Peaks corresponding
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to fatty acids were identified by comparison of their retention times with standard mixtures
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(Larodan, Qualmix Fish; Supelco, FAME Mix). Peak areas were automatically integrated,
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19:0 fatty acid being used as internal standard for quantitative analysis. The concentration
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of each fatty acid or fatty acid group was expressed as g/100 g total FAME.
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2.5. Statistical analysis
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For each chemical measurement, differences among different tissues and seasons
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were analysed using the non-parametric Kruskal-Wallis test (p<0.05). Having demonstrated
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a significant difference somewhere among tissues or among seasons, the non-parametric
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Mann-Whitney-U test was used to find out where the significant (p<0.05) differences were
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[32].
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3. RESULTS AND DISCUSSION
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3.1. Water and lipid contents
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The water contents determined in the different samples are presented in Table 1.
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Water content was higher in all seasons in both muscle tissues (76%-82%) as compared to
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ovary (61-69%) and digestive gland (62%-64%) tissues. The mantle exhibited a higher
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water content than the arm in all seasons except spring. No significant differences were
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observed between ovary and digestive gland throughout the whole year.
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The results of the lipid analyses are also shown in Table 1. A detailed comparison
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among the four tissues considered in this study indicated that the highest lipid content was
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found in the digestive gland (mean values range: 5.38-9.03%), followed by the ovary (mean
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values range: 1.98-3.98%). Very low lipid values (mean values range: 0.26-0.47%) were
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obtained for both muscle tissues. A non-homogeneous fat distribution has been reported for
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octopus and other cephalopods, the digestive gland tissue having been proposed to act as a
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fat storage organ in cephalopod species [11, 33]. This behaviour would be similar to that
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described for lean fish species, whose lipid storage is predominantly in the liver [5, 6]. In
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the present study, a higher lipid content implied a lower water content, according to a
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known inverse ratio between both constituents in marine species [26].
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The lack of major glycogen and lipid reserves in cephalopod tissues favours the
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direct use of protein as an energy supply in such marine species [23, 34]. However, the
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results of the present study clearly indicate that the digestive gland exhibits a remarkably
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high lipid content that, according to previous research on other cephalopod species [35, 36],
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might be employed as a metabolic substrate in common octopus.
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Since the digestive gland may constitute an important lipid depot site, a seasonal
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variation in the lipid content of this gland might be of relevance. Thus, a higher lipid
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content in the digestive gland was observed in autumn, a season characterised by its highly
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abundant diet availability, as compared to previous reports on other cephalopod species
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[37]. However, and due to individual variations, no significant seasonal variation was
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observed, although the highest mean value for the digestive gland lipid content was
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obtained in autumn. In the case of the ovary tissue, the highest lipid content was determined
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in winter specimens, a result that may be explained in terms of the annual reproductive
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cycle reported previously [23, 38].
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3.2. Lipid class analysis
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FFA are mainly produced as a result of the action of lipases and phospholipases on
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high molecular weight lipids such as triglycerides and phospholipids, respectively. The
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FFA concentrations (Table 1) determined in muscle tissues (arm and mantle) were lower
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than in ovary and digestive gland in all seasons, the latter gland exhibiting the highest value
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throughout the whole study. Such high values can be explained as a result of the activity of
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lipases and phospholipases in a visceral tissue [39] that exhibits a remarkably high lipid
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content compared to other tissues (Table 1).
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With respect to the digestive gland, the FFA content exhibited its highest
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concentration in spring, while the lowest was determined in the autumn specimens. This
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pattern was found to be the opposite to that reported for the lipid content (Table 1). In the
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case of the ovary tissue, the highest FFA values were obtained in spring and winter.
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TG content (Table 1) was studied in both the ovary tissue and digestive gland.
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Muscle tissues were not considered at this point due to the low TG values determined
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(<0.005 g/100g wet tissue) and to the relatively low sensitivity of the analytical method
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applied in this study [27]. According to its role as a storage lipid class [5, 6], TG exhibited
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higher concentrations in the digestive gland than in the ovary tissue throughout the whole
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year. According to the pattern exhibited by the lipid content, higher TG contents were
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predicted in autumn than in any other season. However, the results obtained in this study
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did not support such a statement due to the variable differences observed among different
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specimens (Table 1). No significant seasonal variation was determined in the ovary tissue.
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PL analyses (Table 1) evidenced a lower content in muscle tissues than in the ovary
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tissue and digestive gland. The ovary showed the highest content throughout the whole
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year. Muscle tissues exhibited lower values as compared to those reported when
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considering the total edible parts of octopus (0.6 g/ 100 g wet tissue) [19] and other
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cephalopod species (squid, Loligo vulgaris; 1.9 g / 100 g wet tissue) [40]. Some of the
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differences observed in the PL content may be explained in terms of seasonal variation.
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Thus, the highest PL content in ovary was found in winter specimens, while the digestive
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gland exhibited the highest PL level in winter and autumn. No significant differences
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(p>0.05) were observed in both muscle tissues in this study as a result of seasonal variation.
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PL have been described to be important constituents of cell membranes and PL variations
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in marine species have been reported to be caused by external factors [6, 41]. Seasonal PL
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variations determined in the ovary tissue and digestive gland can be explained as a result of
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different metabolic needs during development.
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ST content (Table 1) provided a similar pattern to that determined for FFA in all
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tissues and for TG in the ovary tissue and digestive gland. Thus, the highest ST content was
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found in the digestive gland, confirming previous research on other cephalopod species
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[42]. The ovary tissue exhibited a higher ST content than both muscle tissues throughout
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the whole year. The values obtained in the present study for mantle and arm are in
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agreement with values reported for fish white muscle [43]. The highest ST content (p<0.05)
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for the digestive gland and ovary tissue was found in winter and autumn. In muscle tissues,
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the highest content was observed in autumn.
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Previous research on sterol composition has shown that cholesterol is by far the
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predominant sterol (89-95% of total sterols) in cephalopod species [44, 45]. The resulting
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high cholesterol content in both the digestive gland and the ovary tissue can be explained in
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terms of physiological demands to accomplish rapid maturation events commonly observed
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in cephalopods [23, 45].
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3.3. Fatty acid analysis
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The seasonal variation of the fatty acid composition was investigated in four tissues
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of the octopus (Tables 2-5). In all cases, the most abundant fatty acids were 22:6ω3,
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20:5ω3, 16:0, 18:0, 20:4ω6, 18:1ω9c and 20:1ω9. Certain saturated fatty acids (SFA) such
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as 14:0 and 16:0 exhibited a higher concentration in ovary than in the three other tissues
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studied. By contrast, 18:0 fatty acid showed in most cases higher mean concentrations in
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mantle and arm than in both ovary and digestive gland.
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Monounsaturated fatty acids (MUFA) such as 16:1ω7, 18:1ω7 and 18:1ω9c
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exhibited higher concentrations in the digestive gland than in the other tissues analysed.
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Notably, 20:1ω9 fatty acid showed higher concentrations in the ovary tissue at all seasons,
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as compared to the other three tissues investigated.
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With respect to PUFA, 20:4ω6 fatty acid exhibited a higher concentration in ovary
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than in the other three tissues analysed, except for summer. In the case of 20:5ω3 fatty acid,
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higher contents were found in muscle tissues as compared to the ovary and the digestive
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gland. For 22:6ω3 fatty acid, a similar pattern to 20:5ω3 was observed, this revealing a
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higher concentration of this fatty acid in the muscle tissues than in the two visceral tissues.
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This higher proportion of both ω3 fatty acids in both muscles than in visceral tissues agrees
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to the fact that the former ones showed a higher PL content on lipid basis (mean values:
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64.99 and 59.20 g PL/ 100 g lipid for arm and mantle, respectively) than the ovary and
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digestive gland (46.66 and 11.88 g PL/ 100g lipid, respectively). The results presented in
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this work are in agreement with a previous study on octopus reporting that ω3 PUFA
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proportion in PL (50.3 g/ 100g total FAME) was higher than in TG (24.6 g/ 100g FAME
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[46].
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In relationship to the ω3 series fatty acids, some attention has been focused on the
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importance of the 22:6ω3/20:5ω3 ratio. Thus, previous reports have shown that fish and
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cephalopod species provide a value > 1 for this ratio, while most marine invertebrate
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species exhibit a lower content of 22:6ω3 than 20:5ω3 [10, 19, 31, 40, 47-49]. The results
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presented in this work are in agreement with those results, since a 22:6ω3/20:5ω3 ratio
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higher than 1 was found in all cases (Tables 2-5).
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If fatty acids are considered as fatty acid groups (SFA, MUFA and PUFA), a
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remarkable compositional difference is observed in the digestive gland. Thus, this tissue
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provided a general pattern not affected by seasonal variation consisting of low saturated
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and polyunsaturated contents and a high monounsaturated content, as compared to the other
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three tissues. These results are also in agreement with previous research on other
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cephalopod species [50, 51]. Regarding the PUFA content, both the mantle and arm
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exhibited a higher content than the ovary tissue and digestive gland in all seasons except for
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winter, when no differences could be seen.
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The vast majority of Western countries do not consume adequate levels of ω3 fatty
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acids through natural dietary sources such as fish. Consequently, great attention has been
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recently paid to the ω3/ω6 ratio of foods included in the human diet. This ratio has shown a
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significant effect on the prevention and development of certain health problems [3, 4], the
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recommended ratio for the human being around 1/6 (ω3/ω6) [2]. In the present work, a
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higher ω3/ω6 ratio was found in both muscle tissues as compared with the other two tissues
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at all seasons except for summer, when no significant differences among mantle, ovary and
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digestive gland were observed. Muscle tissues provided in all cases a high ω3/ω6 ratio that
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may be considered as beneficial to the human diet.
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Concerning the seasonal variation of the fatty acid profiles of the four tissues analysed,
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SFA exhibited the lowest (p<0.05) concentration in autumn except for the digestive gland
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where the lowest content (p<0.05) was observed in autumn and winter. MUFA presence
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showed the highest values (p<0.05) in winter for all the tissues, except for the ovary, which
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highest values (p<0.05) were obtained in autumn.. The PUFA content was maximum in
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autumn for the arm and mantle. While both muscle tissues did not exhibit significant
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(p>0.05) seasonal variation in their ω3/ω6 ratio, the ovary tissue and digestive gland
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provided the highest ω3/ω6 ratios (p<0.05) in summer. According to the results reported in
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this work, a general pattern of the seasonal effect on the fatty acid profile of octopus tissues
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could not be concluded. Further research concerning the maturation effect on the fatty acid
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composition is suggested.
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1
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24
19
1
ACKNOWLEDGMENTS
2
The authors wish to thank the ECOBIOMAR and Seafood Chemistry research
3
groups for their valuable help provided during the development of the present work. In this
4
sense, the authors are specially grateful with Mr. José Antonio for his excellent technical
5
assistance. Author M. P. Sieiro thanks the financial support of Vigo University through a
6
doctoral grant. This work was supported by the Comisión Interministerial de Ciencia y
7
Tecnología (CICyT) through the project VEM 2003-20010.
8
20
1
2
21
1
TABLE 2: Fatty acid composition* in different tissues of octopus specimens captured in
winter
Fatty Acids
14:0
15:0
16:0
17:0
18:0
20:0
21:0
24:0
∑ Saturated
14:1
15:1
16:1ω7
18:1ω7
18:1ω9t
18:1ω9c
20:1ω9
22:1ω9,11
∑ Monounsaturated
18:2ω6t
18:2ω6c
20:2ω6
18:3ω3
18:4ω3
20:4ω6
20:5ω3
22:5ω3
22:6ω3
22:6ω3 / 20:5ω3
∑ ω3 / ∑ ω6
∑ Polyunsaturated
2
3
4
5
6
Arm
1.1±0.1a
0.1±0.0
19.2±2.5a
2.2±0.7
8.2±0.8a
nd
0.2±0.1
1.2±0.1
32.3±4.1a
nd
0.5±0.2
0.5±0.3a
2.0±0.2a
nd
2.6±0.4a
3.4±0.1a
1.3±0.3
10.4±0.8a
0.3±0.2
0.1±0.0
0.4±0.2
nd
nd
4.5±0.7a
19.1±0.9a
0.3±0.1
30.7±2.5
1.6±0.2a
9.7±2.2a
55.4±3.9ab
Mantle
0.9±0.2a
nd
17.3±1.2a
2.5±0.4
8.9±0.9a
nd
nd
1.2±0.0
30.7±2.5a
nd
0.4±0.3
0.5±0.1a
1.9±0.1a
nd
2.7±0.2a
3.6±0.3a
1.1±0.3
10.4±0.8a
0.2±0.1
0.2±0.1
0.5±0.1
nd
nd
4.6±0.8a
19.3±0.8a
0.3±0.2
31.7±2.8
1.6±0.2a
9.5±2.7a
57.0±2.4a
Ovary
3.3±0.8b
nd
21.5±1.1b
1.2±0.5
4.2±0.2b
nd
nd
0.9±0.2
31.0±1.2a
nd
nd
0.2±0.2a
2.0±0.3a
0.4±0.1
3.6±0.3b
5.3±0.5b
0.1±0.1
11.7±0.9b
nd
nd
0.1±0.2
nd
nd
8.7±0.8b
15.1±1.1b
0.3±0.3
31.6±1.0
2.1±0.2b
5.4±0.8b
55.9±1.3a
Digestive gland
2.1±0.8c
0.2±0.3
11.8±2.3c
1.5±0.4
6.3±1.0c
nd
0.2±0.3
1.9±0.6
23.7±2.6b
nd
nd
4.5±2.4b
5.4±0.6b
nd
10.6±2.8c
3.2±0.6a
1.4±0.9
25.2±5.2c
nd
0.4±0.4
1.3±0.7
nd
nd
5.2±1.0a
14.7±1.7b
0.1±0.2
28.7±0.8
2.0±0.5b
6.7±1.5b
50.4±6.5b
* Expressed as g/100 g total fatty acid methyl esters. Mean value (n=9) ± standard
deviation is indicated; “nd” indicates a non-detected fatty acid. For each row, data
followed by different superscripts indicate significant differences (p<0.05) among
tissues.
22
TABLE 3: Fatty acid composition* in different tissues of octopus specimens captured in
spring
Fatty Acids
14:0
15:0
16:0
17:0
18:0
20:0
21:0
24:0
∑ Saturated
14:1
15:1
16:1ω7
18:1ω7
18:1ω9t
18:1ω9c
20:1ω9
22:1ω9,11
∑ Monounsaturated
18:2ω6t
18:2ω6c
20:2ω6
18:3ω3
18:4ω3
20:4ω6
20:5ω3
22:5ω3
22:6ω3
22:6ω3 / 20:5ω3
∑ ω3 / ∑ ω6
∑ Polyunsaturated
1
2
3
4
5
Arm
1.5±0.4a
0.1±0.0
18.9±1.7a
2.1±0.2
8.5±0.6a
0.4±0.1
0.5±0.6
1.4±0.1
33.2±2.0a
nd
0.3±0.2
0.6±0.0a
1.7±0.2a
nd
2.0±0.2a
3.4±0.1a
1.7±0.2
9.9±0.9a
0.2±0.1
nd
0.6±0.1
nd
nd
4.1±1.3a
19.1±1.1a
0.5±0.1
30.2±1.6a
1.6±0.2
11.0±2.8a
54.9±1.9a
Mantle
1.1±0.3b
0.2±0.2
18.3±1.6a
2.2±0.1
9.2±0.6b
0.6±0.1
0.1±0.1
1.2±0.1
32.8±2.1a
nd
0.1±0.1
0.6±0.2a
1.6±0.2a
nd
2.1±0.2a
3.2±0.3a
1.5±0.1
9.5±0.7a
0.2±0.1
0.2±0.2
0.5±0.1
nd
nd
4.3±1.7a
19.2±1.3a
0.6±0.1
30.8±2.1a
1.6±0.2
10.7±3.1a
55.83±2.2a
Ovary
3.7±0.2c
0.5±0.1
22.16±1.3b
1.8±0.1
6.4±0.6c
0.2±0.2
nd
1.6±0.5
36.1±2.0b
0.5±0.1
0.2±0.2
0.7±0.0a
1.7±0.2a
1.0±0.3
3.0±0.4b
5.3±0.3b
0.7±0.0
13.2±1.4b
0.6±0.1
nd
0.4±0.2
nd
nd
6.5±1.0b
15.6±1.1b
1.0±0.2
24.8±1.9b
1.6±0.2
5.6±0.9b
49.1±2.1b
Digestive gland
2.6±0.8d
0.6±0.3
13.7±0.5c
2.1±0.3
8.6±0.8ab
0.4±0.2
0.4±0.1
2.1±0.3
30.3±3.1a
0.4±0.3
0.3±0.2
5.1±1.2b
5.0±1.5b
0.3±0.3
8.4±2.8c
2.6±1.0a
1.0±0.8
23.5±3.9c
0.2±0.1
0.9±0.1
1.3±0.4
0.7±0.2
0.8±0.3
5.6±2.2a
18.1±5.4ab
1.0±0.3
16.7±7.1c
1.1±0.6
5.0±1.3b
45.5±3.7c
* Expressed as g/100 g total fatty acid methyl esters. Mean value (n=10) ± standard
deviation is indicated; “nd” indicates a non-detected fatty acid. For each row, data
followed by different superscripts indicate significant differences (p<0.05) among
tissues.
23
TABLE 4: Fatty acid composition* in different tissues of octopus specimens captured in
summer
Fatty Acids
14:0
15:0
16:0
17:0
18:0
20:0
21:0
24:0
∑ Saturated
14:1
15:1
16:1ω7
18:1ω7
18:1ω9t
18:1ω9c
20:1ω9
22:1ω9,11
∑ Monounsaturated
18:2ω6t
18:2ω6c
20:2 ω6
18:3ω3
18:4ω3
20:4ω6
20:5ω3
22:5ω3
22:6ω3
22:6ω3 / 20:5ω3
∑ ω3 / ∑ ω6
∑ Polyunsaturated
Arm
1.8±0.1a
nd
20.0±0.3a
2.2±0.1
7.8±0.4a
nd
0.1±0.1
1.3±0.0
33.2±1.2a
nd
0.5±0.0
0.8±0.1a
1.9±0.2a
nd
2.4±0.0a
3.1±0.1a
1.3±0.0
9.6±1.2ab
0.1±0.0
0.1±0.1
0.4±0.2
nd
nd
3.6±0.1a
21.4±0.4a
0.4±0.1
28.3±0.5
1.4±0.2
12.8±2.3a
54.8±1.2a
Mantle
1.1±0.2a
nd
19.4±1.0a
2.0±0.2
9.7±1.1b
nd
nd
1.1±0.1
33.4±1.2a
nd
0.3±0.1
0.7±0.2a
1.6±0.3ab
nd
2.3±0.2ab
2.9±0.3a
1.2±0.0
9.2±1.0a
0.1±0.1
0.2±0.2
0.5±0.1
nd
nd
4.1±0.4b
20.4±1.1a
0.3±0.2
29.6±2.3
1.5±0.2
10.4±2.5ab
55.1±1.4a
Ovary
4.1±0.4b
nd
24.8±1.9b
0.8±0.0
6.5±0.7c
nd
nd
1.0±0.3
37.3±1.3b
0.3±0.5
nd
0.5±0.1a
1.1±0.1b
1.3±0.2
3.4±0.8b
4.7±0.0b
0.6±0.1
12.1±0.8b
0.2±0.2
nd
0.7±0.2
nd
nd
4.5±0.8b
16.0±1.3b
0.3±0.4
27.4±2.3
1.7±0.3
8.3±1.0b
49.1±2.2b
Digestive gland
3.6±0.6b
0.6±0.1
13.6±1.3c
1.4±0.4
5.7±0.9c
0.3±0.1
0.1±0.1
1.5±0.2
26.6±1.9c
0.5±0.2
0.1±0.2
6.1±1.7b
3.8±1.2c
nd
7.5±0.9c
2.9±1.1a
1.3±1.1
22.4±4.6c
0.1±0.1
1.0±0.2
0.9±0.2
0.8±0.2
1.1±0.2
3.3±1.2a
16.1±1.9b
0.3±0.2
26.9±4.5
1.7±0.5
9.1±2.8b
50.4±4.7b
1
2 * Expressed as g/100 g total fatty acid methyl esters. Mean value (n=10) ± standard deviation
3
is indicated; “nd” indicates a non-detected fatty acid. For each row, data followed
4
by different superscripts indicate significant differences (p<0.05) among tissues.
24
TABLE 5: Fatty acid composition* in different tissues of octopus specimens captured in
autumn
Fatty Acids
14:0
15:0
16:0
17:0
18:0
20:0
21:0
24:0
∑ Saturated
14:1
15:1
16:1ω7
18:1ω7
18:1ω9t
18:1ω9c
20:1ω9
22:1ω9,11
∑ Monounsaturated
18:2ω6t
18:2ω6c
20:2ω6
18:3ω3
18:4ω3
20:4ω6
20:5ω3
22:5ω3
22:6ω3
22:6ω3 / 20:5ω3
∑ ω3 / ∑ ω6
∑ Polyunsaturated
1
2
3
4
5
Arm
1.4±0.2a
nd
16.7±1.7a
1.8±0.2
6.0±1.1
nd
0.1±0.1
1.1±0.1
27.3±2.5a
nd
0.8±0.3
0.6±0.3ab
1.7±0.2a
nd
2.3±0.1a
3.6±0.1a
2.0±0.4
10.3±0.9a
nd
0.1±0.1
0.2±0.2
nd
nd
4.9±0.3a
21.1±0.4a
0.2±0.1
32.9±2.1a
1.6±0.1a
10.7±1.8a
59.2 ±2.3a
Mantle
1.6±0.9b
nd
16.1±2.1a
1.8±0.2
6.8±0.9
nd
nd
1.0±0.1
27.5±2.6a
nd
0.5±0.3
0.3±0.1a
1.6±0.2ab
nd
2.2±0.2a
3.4±0.1a
0.9±0.4
9.1±0.8b
nd
0.1±0.2
0.4±0.1
nd
nd
5.1±0.4a
20.8±0.5a
0.3±0.1
34.2±1.6a
1.6±0.1a
10.1±1.6a
60.6±1.9a
Ovary
3.6±0.7c
0.1±0.2
18.9±1.5b
1.2±0.1
3.6±0.1
nd
0.4±0.5
0.9±0.2
28.6±1.4a
0.4±0.3
0.5±0.2
0.7±0.1b
1.5±0.0b
1.0±0.1
3.0±0.0b
5.5±0.1b
0.6±0.0
13.5±1.1c
0.6±0.0
0.1±0.2
0.6±0.0
nd
nd
9.4±0.5b
13.4±0.7b
1.1±0.4
30.1±2.0b
2.3±0.3b
4.2±0.7b
55.3±2.2b
Digestive gland
2.2±0.1d
0.6±0.1
12.0±0.5c
1.3±0.3
5.4±0.4
0.3±0.3
0.3±0.0
1.6±0.1
23.8±1.9b
0.4±0.1
0.3±0.1
4.0±0.5c
3.9±0.6c
0.2±0.2
10.0±0.3c
2.9±0.5c
1.5±0.7
23.2±1.8d
0.1±0.0
1.0±0.3
1.2±0.1
0.6±0.1
0.8±0.4
5.2±0.7a
14.4±0.8b
0.8±0.2
28.3±1.4b
2.0±0.3b
6.2±1.1c
52.3±2.8c
* Expressed as g/100 g total fatty acid methyl esters. Mean value (n=10) ± standard
deviation is indicated; “nd” indicates a non-detected fatty acid. For each row, data
followed by different superscripts indicate significant differences (p<0.05) among
tissues.
25