Lipid Class Content Research Articles

Differential responses to ocean acidification between populations of Balanophyllia elegans corals from high and low upwelling environments.

Ocean acidification (OA), the global decrease in surface water pH from absorption of anthropogenic CO2 , may put many marine taxa at risk. However, populations that experience extreme localized conditions, and are adapted to these conditions predicted in the global ocean in 2,100, may be more tolerant to future OA. By identifying locally adapted populations, researchers can examine the mechanisms used to cope with decreasing pH. One oceanographic process that influences pH is wind-driven upwelling. Here we compare two Californian populations of the coral Balanophyllia elegans from distinct upwelling regimes, and test their physiological and transcriptomic responses to experimental seawater acidification. We measured respiration rates, protein and lipid content, and gene expression in corals from both populations exposed to pH levels of 7.8 and 7.4 for 29days. Corals from the population that experiences lower pH due to high upwelling maintained the same respiration rate throughout the exposure. In contrast, corals from the low upwelling site had reduced respiration rates, protein content and lipid-class content at low pH exposure, suggesting they have depleted their energy reserves. Using RNA-Seq, we found that corals from the high upwelling site upregulated genes involved in calcium ion binding and ion transport, most likely related to pH homeostasis and calcification. In contrast, corals from the low upwelling site downregulated stress response genes at low pH exposure. Divergent population responses to low pH observed in B.elegans highlight the importance of multi-population studies for predicting a species' response to future OA.

Enhanced triacylglycerol production in the diatom Phaeodactylum tricornutum by inactivation of a Hotdog-fold thioesterase gene using TALEN-based targeted mutagenesis

BackgroundIn photosynthetic oleaginous microalgae, acyl-CoA molecules are used as substrates for the biosynthesis of membrane glycerolipids, triacylglycerol (TAG) and other acylated molecules. Acyl-CoA can also be directed to beta-oxidative catabolism. They can be utilized by a number of lipid metabolic enzymes including endogenous thioesterases, which catalyze their hydrolysis to release free fatty acids. Acyl-CoA availability thus plays fundamental roles in determining the quantity and composition of membrane lipids and storage lipids.ResultsHere, we have engineered the model diatom Phaeodactylum tricornutum to produce significantly increased TAGs by disruption of the gene encoding a Hotdog-fold thioesterase involved in acyl-CoA hydrolysis (ptTES1). This plastidial thioesterase can hydrolyze both medium- and long-chain fatty acyl-CoAs, but has the highest activity toward long-chain saturated and monounsaturated fatty acyl-CoAs. The maximum rate was found with oleoyl-CoA, which is hydrolyzed at 50 nmol/min/mg protein. The stable and targeted interruption of acyl-CoA thioesterase gene was achieved using a genome editing technique, transcription activator-like effector nucleases (TALENs). Disruption of native ptTES1 gene resulted in a 1.7-fold increase in TAG content when algal strains were grown in nitrogen-replete media for 8 days, whereas the content of other lipid classes, including phosphoglycerolipids and galactoglycerolipids, remained almost unchanged. The engineered algal strain also exhibited a marked change in fatty acid profile, including a remarkable increase in 16:0 and 16:1 and a decrease in 20:5. Nitrogen deprivation for 72 h further increased TAG content and titer of the engineered strain, reaching 478 μg/109 cells and 4.8 mg/L, respectively. Quantitative determination of in vivo acyl-CoAs showed that the total acyl-CoA pool size was significantly higher in the engineered algal strain than that in the wild type.ConclusionsThis study supports the role of ptTES1 in free fatty acid homeostasis in the plastid of Phaeodactylum and demonstrates the potential of TALEN-based genome editing technique to generate an enhanced lipid-producing algal strain through blocking acyl-CoA catabolism.

Energy cost of the onshore transport of postlarvae of the Caribbean spiny lobster, Panulirus argus

Recent studies suggest that energy reserves play a crucial role in the recruitment of postlarval spiny lobsters. After a protracted pelagic larval phase that develops in oceanic waters, the final stage phyllosoma larva metamorphoses into a non-feeding postlarva (puerulus) that actively swims shoreward to settle in shallow coastal habitats and does not resume feeding until after the molt into juvenile. We examined the content of total protein (TP), total lipid (TL), and lipid classes in five developmental stages of the spiny lobster, Panulirus argus (Latreille, 1804), involved in the transition from pelagic to benthic life: final stage phyllosomata, nektonic pueruli, transparent benthic pueruli (newly settled), pigmented pueruli, and first-instar juveniles; collected in autumn 2012 and spring 2013. TL decreased progressively with development, from 26% of dry weight in phyllosomata to 7% in juveniles in autumn (a 73% decrease), and from 25% to 6% in spring (a 76% decrease). In all stages, phospholipid accounted for approximately 80%–87% of TL. TP was higher in all three pueruli substages than in phyllosomata and juveniles. Although season did not significantly affect either TL or TP content, the decline in TL between final phyllosomata and nektonic pueruli was greater in autumn, suggesting a greater energy cost of metamorphosis at warmer temperatures, whereas the decline in TL between nektonic and transparent benthic pueruli was more marked in spring, when the Yucatan Current is stronger, potentially increasing the energy cost of shoreward swimming. These findings may partially explain the interannual seasonal settlement patterns observed in this species.

Seasonal changes in lipid class content in mussels Mytilus spp. from Rakkfjorden in the Norwegian Sea and Kandalaksha Bay of the White Sea

The aim of the study was to increase knowledge regarding baseline biology of Arctic mussels (Mytilus spp.) in terms of lipid class content at different stages of reproductive development throughout the year. Lipid composition in the mantle and digestive glands were studied in mussels from the intertidal and subtidal zones of mussel beds located in the Norwegian Sea and the White Sea. Thin-layer chromatography was used to quantify phospholipids, triacylglycerols, sterols and their esters. The differences in climatic and hydrological conditions between the studied geographical locations of mussel beds were reflected not only in the timing and duration of the mussel’s reproductive stages, mainly active gametogenesis (stage II) and maturity (stage III), but also in the lipid composition of mussel mantle and digestive gland. The differences in environmental conditions between intertidal and subtidal zones of the studied mussel beds were also reflected in the lipid composition of mussels from both geographic locations, and determined the modifications of their lipid composition during the reproductive development. Although environmental conditions caused specificity in the distribution of the lipid composition in the mantle and digestive gland of Arctic Mytilus spp., the lipid composition variations that accompany the reproductive processes in bivalve mollusks were not affected.

A Comparative Study of Lipid Composition of an Undervalued Crustacean (Munida spp.) Captured in Winter and Summer

ABSTRACTThis research was focused on the lipid fraction of an undervalued crustacean (lobster krill; Munida spp.) and the comparative study of individuals captured at winter and summer seasons. For this purpose, seasonal variations were analyzed in the muscle (i.e., tail meat) for proximate composition, lipid class distribution, and fatty acid (FA) profile. Mean total lipids ranged from 0.75 ± 0.08% (summer) to 0.92 ± 0.06% (winter), moisture from 77.94 ± 0.25% (winter) to 78.62 ± 0.38% (summer), and protein from 17.93 ± 0.46% (summer) to 18.22 ± 0.46% (winter). Regarding lipid class content (% of total lipids), phospholipids ranged from 64.85 ± 1.29 (summer) to 67.85 ± 2.56 (winter), sterols from 12.15 ± 0.35 (winter) to 13.54 ± 0.54 (summer), triacylglycerols from 0.04 ± 0.02 (summer) to 1.25 ± 0.88 (winter), and free FA from 1.14 ± 0.72 (winter) to 2.19 ± 0.34 (summer). In both seasons, the most abundant FA were C22:6ω3, C16:0, C18:1ω9, and C20:5ω3. Polyunsaturated fatty acids (PUFA) were found to be the most abundant group in samples from both seasons (50.4–55.3%). Higher PUFA values were determined in summer samples, while a highly valuable ω3/ω6 ratio (from 9.11 ± 1.12 in summer to 10.40 ± 1.39 in winter) was observed. It is concluded that in spite of being a low-fat product, the lipid fraction of this underutilized crustacean can provide highly valuable constituents.

Feeding Relationship between Octopus vulgaris (Cuvier, 1797) Early Life-Cycle Stages and Their Prey in the Western Iberian Upwelling System: Correlation of Reciprocal Lipid and Fatty Acid Contents.

Under the influence of the Western Iberian upwelling system, the Iberian Atlantic coast holds important hatcheries and recruitment areas for Octopus vulgaris. Recently identified as an octopus hatchery, the Ría de Vigo harbors an important mesozooplankton community that supports O. vulgaris paralarvae during the first days of their planktonic stage. This study represents a preliminary approach to determine the nutritional link between wild O. vulgaris hatchlings, paralarvae and their zooplankton prey in the Ría de Vigo, by analyzing their lipid class content and fatty acid profiles. The results show that octopus hatchlings are richer in structural lipids as phospholipids and cholesterol, while the zooplankton is richer in reserve lipids like triacylglycerol and waxes. Zooplankton samples are also particularly rich in C18:1n9 and 22:6n3 (DHA), that seem to be successfully incorporated by O. vulgaris paralarvae thus resulting in a distinct fatty acid profile to that of the hatchlings. On the other hand, content in C20:4n6 (ARA) is maintained high through development, even though the zooplankton is apparently poorer in this essential fatty acid, confirming its importance for the development of O. vulgaris paralarvae. The content in monounsaturated fatty acids, particularly C18:1n7, and the DHA: EPA ratio are suggested as trophic markers of the diet of O. vulgaris paralarvae.

Comparative analysis of lipid profile and in vitro cytotoxic activity of fermented and unfermented soybean extracted by supercritical CO2 extraction

Comparative analysis of fermented and unfermented soybean lipid were performed by supercritical CO2 extraction (SC-CO2), GC, RP-HPLC-ELSD/APCI-MS techniques, which caused to tentatively identify 31 lipids, determine fatty acid composition and lipid classes contents. Major observations were that there were significant variations of fatty acid composition involved in the amounts of palmitic acid and oleic acid increased (p<0.001), and α-linolenic acid decreased (p<0.01), and significant changes in the contents of lipid classes relating to fatty acids, diacylglycerols and triacylglycerols (p<0.001) during fermentation. Notably, observably difference in cytotoxic activity of fermented and unfermented soybean lipid against cancer cells were first evaluated, and as a result, fatty acids fraction obtained during fermentation contributed to the efficacy by significantly inducing cell apoptosis (p<0.01). These results indicate that increased lipid classes caused by fermentation are important bioactive sources, worthy of further investigation.

Membrane Lipid Microenvironment Modulates Thermodynamic Properties of the Na+-K+-ATPase in Branchial and Intestinal Epithelia in Euryhaline Fish In vivo.

We have analyzed the effects of different native membrane lipid composition on the thermodynamic properties of the Na+-K+-ATPase in different epithelia from the gilthead seabream Sparus aurata. Thermodynamic parameters of activation for the Na+-K+-ATPase, as well as contents of lipid classes and fatty acids from polar lipids were determined for gill epithelia and enterocytes isolated from pyloric caeca, anterior intestine and posterior intestine. Arrhenius analyses of control animals revealed differences in thermal discontinuity values (Td) and activation energies determined at both sides of Td between intestinal and gill epithelia. Eyring plots disclosed important differences in enthalpy of activation (ΔH‡) and entropy of activation (ΔS‡) between enterocytes and branchial cells. Induction of n-3 LCPUFA deficiency dramatically altered membrane lipid composition in enterocytes, being the most dramatic changes the increase in 18:1n-9 (oleic acid) and the reduction of n-3 LCPUFA (mainly DHA, docosahexaenoic acid). Strikingly, branchial cells were much more resistant to diet-induced lipid alterations than enterocytes, indicating the existence of potent lipostatic mechanisms preserving membrane lipid matrix in gill epithelia. Paralleling lipid alterations, values of Ea1, ΔH‡ and ΔS‡ for the Na+-K+-ATPase were all increased, while Td values vanished, in LCPUFA deficient enterocytes. In turn, Differences in thermodynamic parameters were highly correlated with specific changes in fatty acids, but not with individual lipid classes including cholesterol in vivo. Thus, Td was positively related to 18:1n-9 and negatively to DHA. Td, Ea1 and ΔH‡ were exponentially related to DHA/18:1n-9 ratio. The exponential nature of these relationships highlights the strong impact of subtle changes in the contents of oleic acid and DHA in setting the thermodynamic properties of epithelial Na+-K+-ATPase in vivo. The effects are consistent with physical effects on the lipid membrane surrounding the enzyme as well as with direct interactions with the Na+-K+-ATPase.

Relationships among Proximate Components and Energy Density of Juvenile Atlantic Estuarine Fishes

AbstractInformation on the energy density of juvenile fishes is needed to inform food web and bioenergetic models. Several approaches may be used to estimate energy density, and although these approaches are expected to yield similar estimates, the accuracy of such estimates has not been assessed. Estuarine fishes have unique life history strategies that influence the water, protein, lipid, and ash composition of their tissues. Because proximate components vary among species, the preferred approaches for estimating energy density from these components may also differ. We investigated the suitability of five approaches to estimate energy density measured by bomb calorimetry from water content for juvenile Summer Flounder Paralichthys dentatus, Striped Bass Morone saxatilis, and Atlantic Croaker Micropogonias undulatus. Approaches were based on the following: (1) relationships between water and percent composition, (2) relationships between water and the mass of proximate components, (3) water content alone (by percentage and by mass), (4) percent water and fish mass, and (5) published relationships between energy density and percent dry weight. The mean predicted energy densities from alternative approaches were generally within 10% of the mean energy densities measured by bomb calorimetry (4.21 kJ/g to 4.94 kJ/g). For Summer Flounder and Atlantic Croakers, regressions based on the percent water from whole fish provided estimates of energy density closest to those from bomb calorimetry, and including fish mass improved the accuracy of energy density estimates for Striped Bass. Energy density calculated from percent composition overestimated measured energy density, even with conservative lipid‐to‐energy conversion factors; this was most pronounced for individuals with energy densities less than 5 kJ/g. Because lipid‐to‐energy conversion factors may not be temporally stable or spatially invariant, further research is needed on the energy content of lipid classes in fishes. The types of lipids used for energy storage likely vary among life stages and species, and extrapolating approaches to different size‐classes or species groups may bias estimates of energy content.

Microalgae lipid characterization.

To meet the growing interest of utilizing microalgae biomass in the production of biofuels and nutraceutical and pharmaceutical lipids, we need suitable analytical methods and a comprehensive database for their lipid components. The objective of the present work was to demonstrate methodology and provide data on fatty acid composition, lipid class content and composition, characteristics of the unsaponifiables, and type of chlorophylls of five microalgae. Microalgae lipids were fractionated into TAG, FFA, and polar lipids using TLC, and the composition of fatty acids in total lipids and in each lipid class, hydrocarbons, and sterols were determined by GC-MS. Glyco- and phospholipids were profiled by LC/ESI-MS. Chlorophylls and their related metabolites were qualified by LC/APCI-MS. The melting and crystallization profiles of microalgae total lipids and their esters were analyzed by DSC to evaluate their potential biofuel applications. Significant differences and complexities of lipid composition among the algae tested were observed. The compositional information is valuable for strain selection, downstream biomass fractionation, and utilization.

Changes in lipid class content and composition of Isochrysis sp. (T-Iso) grown in batch culture

For decades, the microalgae Isochrysis spp. have been widely utilised as a live feed in aquaculture practices. This species possesses a number of favourable characteristics, notably its long-chain omega-3 polyunsaturated fatty acid (LC n-3 PUFA) content; primarily docosahexaenoic acid (DHA, 22:6n-3). This article describes the lipid class content and composition of this microalga grown in batch culture, covering the entirety of lag, log and stationary growth phases. The total lipid was highest in the lag phase (27 pg/cell). Total lipid significantly decreased in the exponential growth (7 pg/cell), then steadily increasing for the remainder of growth. The increase in total lipid was due to the accumulation of neutral lipid in the form of triacylglycerides. The DHA content (pg/cell) of the neutral lipid remained relatively unchanged for the duration of growth, with the influx of fatty acids being primarily myristic and palmitic acids. DHA (pg/cell) was found at relatively uniform amounts across all lipid classes. However, the DHA content as a percentage differed greatly between classes. The polar lipid class had a significantly higher DHA content, which peaked at 38 % of all polar lipid in log growth. The primary PUFA species present in the glycolipid class was stearidonic acid (18:4n-3). This work gives an overview of the lipid content and composition of Isochrysis sp. (T-Iso) over the entirety of its growth under batch culture. The lipid profile for this species at different stages of culture provides a basal data set that is useful for comparative studies using this organism.

The effect of caralluma fimbriata extract on metabolic parameters in high-fat fed wistar rats

The effect of caralluma fimbriata extract on metabolic parameters in high-fat fed wistar rats

Erratum to: Does the trophic habitat influence the biochemical quality of the gonad of Octopus vulgaris? Stable isotopes and lipid class contents as bio-indicators of different life-cycle strategies

This study aims to test whether environmental conditions including the trophic habitat and diet impact the biochemical composition of storage organs and affect the nutritional quality of eggs of Octopus vulgaris. Trophic habitat and gonad quality of neighbouring populations off the Portuguese coast, subject to different oceanographic regimes, were compared using the digestive gland and beaks as recorders of trophic and habitat preferences, and gonads as indicators of egg quality. Cholesterol, phospholipids and triacylglycerol content, essential fatty acid (EFA) profile of the digestive gland and stable isotopes, δ15N and δ13C, in the buccal mass flesh and beaks were indicators of the differences in the trophic habitat between populations. For gonad quality, the same bio-indicators were used to identify differences with maturation. The study shows that, although diet influences the EFA profile of the gonads to a certain degree, the main lipid content, phospholipids and cholesterol content in the gonads are not influenced by habitat conditions. This, therefore, suggests that O. vulgaris is able to influence the quality of egg content independent of diet. The species is believed to be an income breeder which attains maturity upon reaching a sufficient condition level, then channelling energy directly from food to gonad development.

Does the trophic habitat influence the biochemical quality of the gonad of Octopus vulgaris? Stable isotopes and lipid class contents as bio-indicators of different life-cycle strategies

Does the trophic habitat influence the biochemical quality of the gonad of Octopus vulgaris? Stable isotopes and lipid class contents as bio-indicators of different life-cycle strategies

Lipid Classes and Fatty Acid Regiodistribution in Triacylglycerols of Seed Oils of Two Sambucus Species (S. nigra L. and S. ebulus L.)

The oil content and fatty acid composition of total lipids (TLs) and main lipid classes (NLs- neutral and PLs- polar lipids) in seeds of two wild Sambucus species (S. nigra and S. ebulus) from Transylvania (Romania) were determined by capillary gas chromatography (GC-MS). In addition, the positional distribution of fatty acids in seed triacylglycerols (TAGs) was determined by hydrolysis with pancreatic lipase. The seeds were found to be rich in fat (22.40–24.90 g/100g) with high amounts of polyunsaturated fatty acids (PUFAs) ranging from 68.96% (S. ebulus) to 75.15% (S. nigra). High ratios of PUFAs/SFAs (saturated fatty acids), ranging from 7.06 (S. nigra) to 7.64 (S. ebulus), and low ratios of n-6/n-3, ranging from 0.84 (S. nigra) to 1.51 (S. ebulus), were determined in both oils. The lipid classes/subclasses analyzed (PLs, MAGs—monoacylglycerols, DAGs—diacylglycerols, FFAs—free fatty acids, TAGs and SEs—sterol esters) were separated and identified using thin-layer chromatography. The fatty acid compositions of the TAG fractions were practically identical to the profiles of TLs, with the same dominating fatty acids in both analyzed species. SEs and FFAs, were characterized by high proportions of SFAs. The sn-2 position of TAGs was esterified predominantly with linoleic acid (43.56% for S. nigra and 50.41% for S. ebulus).

Growth, lipid production and metabolic adjustments in the euryhaline eustigmatophyte Nannochloropsis oceanica CCALA 804 in response to osmotic downshift

We investigated the effects of osmotic downshift induced by the transfer of Nannochloropsis oceanica CCALA 804 from artificial seawater medium (27gL(-1) NaCl) to the same medium without NaCl or freshwater modified BG-11 medium (mBG-11) as a function of photosynthetically active radiation (170, 350, or 700μmol photon m(-2)s(-1)). Alterations in growth, total fatty acid (FA) content and FA composition of individual lipid classes, and in relative contents of metabolites relevant to osmotic adjustments were studied. Cells displayed remarkable tolerance to the osmotic downshift apart from some swelling, with no substantial lag or decline in cell division rate. Biomass accumulation and chlorophyll a content were enhanced upon downshifting, especially under the highest irradiance. The highest chlorophyll a and eicosapentaenoic acid (EPA) biomass and culture contents were determined in the cultures grown in mBG-11. Two days after transfer to 0 g L(-1) NaCl, the proportion in total acyl lipids of the major chloroplast galactolipid monogalactosyldiacylglycerol, a major depot of EPA, increased twofold, along with a modest change in the proportion of digalactosyldiacylglycerol (DGDG). EPA percentage decreased in DGDG and increased in the extraplastidial lipid phosphatidylethanolamine. Metabolite profiling by GC-MS analysis revealed a sharp decrease in metabolites potentially involved in osmoregulation, such as mannitol and proline, while proline-cycle intermediates and some free sugars increased. The stress-induced polyamine spermidine decreased ca. one order of magnitude, while its catabolic product-the non-protein amino acid γ-amino butyric acid-increased twofold, as did the stress-related sugars trehalose and talose. Biochemical mechanisms governing osmotic plasticity and implications for optimization of EPA production by N. oceanica CCALA 804 under variable cultivation conditions are discussed.

Influence of an intermittent food supply on energy storage by the subpolar deposit feeder Yoldia hyperborea (Bivalvia: Nuculanidae)

Food supply for deposit feeders varies from highly seasonal phytodetritus to a steady source of older organic matter, resulting in contrasting patterns of nutrient uptake and storage. To identify patterns in energy storage and feeding behaviour driven by different food conditions for the circumpolar deposit-feeding protobranch bivalve Yoldia hyperborea, we measured variations in cytological (digestive cell height) and biochemical (lipid class, fatty acid, glycogen, and protein content) components during controlled experiments. Three treatments with organisms in sediment with high refractory organic matter (12 % OM) were exposed to different feeding regimes resembling (a) the annual spring bloom settlement, (b) low food availability during winter, and (c) sporadic resuspension events. Yoldia exposed to a diatom-supplemented diet showed significantly higher mean values for digestive cell height (28.44 μm), glycogen (30.4 mg g−1 dry mass, DM), diatom-specific fatty acids, and total lipid (TL) levels (14.4 mg g−1 DM), but lower protein concentrations, than in non-supplemented treatments (digestive cell height 20.34 μm; glycogen 9.23 mg g−1 DM; TL 6.7 mg g−1 DM). All analyses showed no effect of resuspension events; thus, it was unlikely that resuspension improved sediment nutritional value. In the absence of recently deposited diatoms, Y. hyperborea did not increase nutrient storage, suggesting that significant amounts of older refractory OM are not used for growth or reproduction. The rapid storage of nutrients derived from diatoms demonstrates the role of seasonal episodic events of settling algae in the nutrition of subpolar Y. hyperborea and in the transfer of energy from the water column to the benthos.

Variation of content of lipid classes, sterols and fatty acids in gonads and digestive glands of Scrobicularia plana in relation to environment pollution levels

Lipids are central for energy metabolism and their fate in bivalves is closely linked to environmental conditions and gametogenic cycle. In order to assess the pollution impact on lipid metabolism of bivalves, storage and structure lipids from samples of Scrobicularia plana were studied. These samples were collected during sexual maturity both from estuaries considered contaminated (Goyen and Blavet) and from a reference site (Bay of St Brieuc) for comparison. Lipids were extracted from the gonads and the digestive glands and further separated by column chromatography. Fatty acids and sterols were then analyzed by gas chromatography–mass spectrometry. Correlations were shown between dioxin-like compounds (Eq-TCDD) and triacyglycerol levels (TAG). In the same way, glycolipids and contamination by polycyclic aromatic hydrocarbons (PAH) and pollutants with estrogenic activity seem to be closely related. In a second time, lipid indices (ratio between storage and structure lipids) were evaluated. Whereas these indices are often used in fish to assess habitat quality with regards to differential anthropogenic pressure, the ratio TAG/sterols was not here significantly influenced by the site of origin of S. plana. Intersite fluctuations of the ratio TAG/phospholipids also remained very limited. This could be explained by the limited contamination level in studied sites but also by a contrasted response from organisms in different taxa (bivalves vs. fish). Environmental pollution is not the only factor able to induce changes in lipid classes. The trophic wealth seemed to be different between the reference site and contaminated estuaries, the total organic carbon content being higher in muddy estuarine sediments.

Changes in lipid composition of different tissues of common octopus (Octopus vulgaris) during short-term starvation

In this work, we study the variations in concentration (mg 100 g−1 dry weight) and total content (mg individual−1) of different lipid classes in muscle and the digestive gland of Octopus vulgaris during an 8-day starvation period. In all the samples analysed, polar lipids (PL) predominated in muscle (267.3–337.2 mg 100 g−1) compared with neutral lipids (66.9–104.7 mg 100 g−1). A significant positive tendency was observed in muscle for the content and concentration of monoglycerides as a consequence of starvation (P < 0.05). Furthermore, a higher cholesterol (CHO) content was detected in this tissue after the fourth day of starvation compared with the fed animals (P < 0.05). Neutral lipids predominated in the digestive gland (12 958–14 151 mg 100 g−1) compared with PL (3157–6517 mg 100 g−1), with triglycerides, free fatty acids and monoglycerides being the major lipid classes. The concentration of PL and monoglycerides showed a positive trend with starvation, while the triacylglycerol showed a negative tendency (P < 0.05). The results suggest that triglycerides and CHO are transported simultaneously from the digestive gland to the muscular tissues during starvation and the preferential use of PL and CHO during growth phases. It was estimated that lipids contributed 26% of the energy costs of the animals during starvation, mainly in the form of triglycerides from the digestive gland.

Effect of conventional and pressure frying on lipids and fatty acid composition of fried chicken and oil

Lipid class and fatty acid profile of pressure fried (PF) and conventionally fried (CF) chicken and medium of frying were evaluated. Depending on the frying cycle, neutral lipid (NL) content of PF chicken varied from 75-86% as compared to that of CF (84-90%). Similarly, glycolipid (GL) content varied from 11-21% in PF and from 9-12% in case of CF. Phospholipid (PL) was the least among lipid classes in both the products. The fresh frying medium (oil before frying cycle started), NL, GL and PL were 89, 10 and 0.33%, respectively. After the frying cycles were over, NL content of oil used for CF decreased to 82% and GL content increased from 10 to 17%. There was no significant difference (p ≥ 0.05) between the contents of lipid classes of oil used for PF or CF. Fried chicken and frying medium had higher concentration of linoleic acid and oleic acid irrespective of the frying cycle or frying method. PF chicken had moisture content in the range of 56-58% and total fat was 14% whereas in case of CF chicken it ranged from 49-52% and 18% respectively. TBA and FFA values of CF chicken and oil on repeated frying were higher (p ≤ 0.05) than PF. In comparison to conventional frying, pressure frying resulted in relatively tender and juicier product presumably due to better retention of moisture (p ≤ 0.05) and low oil uptake.