Lipids and of fatty acids of edible crabs of the north-western Pacific

Shelf-life of cooked meat of southern king crab (Lithodes santolla) and false king crab (Paralomis granulosa) during refrigerated storage

Lithodes santolla (SKC) and Paralomis granulosa (FSKC) are economically important resources exploited in southern South America. The effect of refrigerated storage (4 °C on flake ice) on physico-chemical (pH, thiobarbituric reactive substances (TBARs), total volatile basic nitrogen (TVB-N), water holding capacity (WHC), and water content (WC)), microbiological (total viable mesophilic bacteria (TVMC), psychrotrophic bacteria (TVPC), Staphylococcus spp, coliforms, enterobacteria, molds and yeasts) and sensory (odor, appearance, texture, juiciness, and taste) parameters was analyzed in the cooked SKC and FSKC merus. For each species, cooked merus from 36 animals were randomly distributed into 6 groups, corresponding to 0, 2, 5, 8, 11, and 14 days of storage. On each day, samples were taken for physico-chemical (n = 6), microbiological (n = 3), and sensory (n = 15) analyses. The pH values increased over time (P < 0.01 in both species), the TBARs only increased in FSKC (P = 0.008), whereas the TVB-N significantly rose only in SKC (P = 0.001). The WHC and the WC did not change over time for any of the king crab species (P > 0.05) in all cases. The presence of TVCM, TVCP, and Staphylococcus spp. in both species was observed from day 0. Furthermore, pathogenic microorganisms (S. aureus, coliforms, and enterobacteria) were not detected, and only the TVCP in SFKC reached the suggested microbial limit after 11 days. All sensory scores significantly decreased (P < 0.001) over time, but the quality of both king crab species remained acceptable until the 11th day. These findings suggest that the shelf-life of cooked merus was 11 and 8 days for SKC and SFKC, respectively, when stored at 4 °C with the presence of flake ice. These contributions consist of elucidating the shelf-life of these economically important seafood products and providing insights into their quality maintenance during storage.

Transcriptome analysis provides insights into the high ability to synthesize fatty acids in "yellow oil" mud crab (Scylla paramamosain)

Yellow oil mud crab (YOC) is a new variant of mud crab (Scylla paramamosain), which was attracted much attention in recent years due to its high level of nutrition. However, the nutritive values and the physiological changes in YOC have not been clearly understood. In this study, we aimed to identify the nutrient compositions (including total carotenoid content (TCC), total lipid content (TLC), total antioxidant capacity (TAC), and fatty acids) and differences in genes related to the biosynthesis of fatty acids using transcriptome analysis in YOC in comparison with those of normal mud crabs. As a result, observations on the morphological characteristics showed that the YOC exhibits a difference in the color of the muscle, gills (orange-yellow), and hemolymph (yellow) compared with the normal female crabs (NFC) (blue or nattier blue). The TCC and TLC (84.96 ± 9.65 μg/g in muscle and 1.39 ± 0.10 μg/mL in hemolymph) or TAC (1.52 ± 0.17 mM in hemolymph) of YOC were higher than that of NFC and normal male crab (NMC). YOC had lower saturated fatty acids, but higher unsaturated fatty acids, as well as the ratio of n-3/n-6 of fatty acids in muscle and hemolymph, compared with those of NFC and NMC. Furthermore, the transcriptome profile revealed that the unigenes in YOC were enriched in the synthesis of n-3 fatty acids. Furthermore, more unigenes related to 'Biosynthesis of unsaturated fatty acids' were identified in muscle and hemocytes, while fewer were in the gonads of YOC. Additionally, the positive (in muscle and hemocytes) and a negative correlation (in gonads) between expressions of unigenes and contents of TLC, TCC, and UFA were found, indicating a better synthesis ability of fatty acids in the muscle and hemocytes of YOC. Overall, compared to NFC and NMC, YOC has higher nutrients and is a better food nutrient source for humans.

Crabs Eriocheir japonica and Paralithodes camtschaticus Are a Rich Source of Lipid Molecular Species with High Nutritional Value

Due to their valuable meat and hepatopancreas, the world's most famous delicacies, crabs, have become target species of commercial fisheries and aquaculture. By methods of supercritical fluid and high-performance liquid chromatography, coupled with high resolution mass spectrometry, we analyzed triacylglycerols (TG) and phospholipids (PL)-glycerophosphoethanolamines (PE), glycerophosphocholines (PC), glycerophosphoserines (PS), and glycerophosphoinositols (PI)-in the hepatopancreas and muscles of the Japanese mitten crab Eriocheir japonica and the red king crab Paralithodes camtschaticus inhabiting the Sea of Japan. TGs were the main class of lipids in the crab hepatopancreas, while they were found in trace amounts in muscle. TGs of E. japonica differed from those of P. camtschaticus by a higher content of 16:0, 16:1, 18:2, and 20:4 FA and a lower content of eicosapentaenoic and docosahexaenoic acids. The Japanese mitten crab differed from the red king crab by a lower content of molecular species with eicosapentaenoic acid in PC and PI; an increased content of arachidonic acid in PE, PS, and PI; and a lower content of molecular species with docosahexaenoic acid in PE in the hepatopancreas and muscles. The high nutritional value of the crabs E. japonica and P. camtschaticus was confirmed by a high content of molecular species of lipids with n-3 polyunsaturated fatty acids. The data of the lipid molecular species profile provide new background information for future studies on biochemistry and aquaculture of crabs.

Determination of Fatty Acid Profile in Processed Fish and Shellfish Foods

Seafood products are a crucial dietary source of n-3 polyunsaturated fatty acids (n-3 PUFA), which are essential for human health. However, the presence of these n-3 PUFA may be subject to changes related to different processing methods. The aim of this study was to determine the fatty acid composition, focusing on n-3 PUFA, in different processed fish and shellfish products of both EU and non-EU origin. The products were purchased from supermarkets and ethnic food shops in Messina (Italy). Gas chromatography with a flame-ionization detector (GC-FID) was used for analysis. Based on the fatty acid profile, the atherogenicity index (AI), thrombogenicity index (TI), and flesh lipid quality index (FLQ) were determined: 0.13-1.04 (AI), 0.19-0.89 (TI), and 0.41-29.90 (FLQ). The percentages of saturated (SFA), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids fell within the following ranges: 13.55-50.48%, 18.91-65.58%, and 13.84-52.73%, respectively. Considering that all samples showed low AI and TI indices and that all processed fish products proved to be a good source of beneficial PUFAs, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), their consumption is recommended for humans.

Marine Natural Products from the Russian Pacific as Sources of Drugs for Neurodegenerative Diseases

Neurodegenerative diseases are growing to become one of humanity's biggest health problems, given the number of individuals affected by them. They cause enough mortalities and severe economic impact to rival cancers and infections. With the current diversity of pathophysiological mechanisms involved in neurodegenerative diseases, on the one hand, and scarcity of efficient prevention and treatment strategies, on the other, all possible sources for novel drug discovery must be employed. Marine pharmacology represents a relatively uncharted territory to seek promising compounds, despite the enormous chemodiversity it offers. The current work discusses one vast marine region-the Northwestern or Russian Pacific-as the treasure chest for marine-based drug discovery targeting neurodegenerative diseases. We overview the natural products of neurological properties already discovered from its waters and survey the existing molecular and cellular targets for pharmacological modulation of the disease. We further provide a general assessment of the drug discovery potential of the Russian Pacific in case of its systematic development to tackle neurodegenerative diseases.

Current Progress in Lipidomics of Marine Invertebrates

Marine invertebrates are a paraphyletic group that comprises more than 90% of all marine animal species. Lipids form the structural basis of cell membranes, are utilized as an energy reserve by all marine invertebrates, and are, therefore, considered important indicators of their ecology and biochemistry. The nutritional value of commercial invertebrates directly depends on their lipid composition. The lipid classes and fatty acids of marine invertebrates have been studied in detail, but data on their lipidomes (the profiles of all lipid molecules) remain very limited. To date, lipidomes or their parts are known only for a few species of mollusks, coral polyps, ascidians, jellyfish, sea anemones, sponges, sea stars, sea urchins, sea cucumbers, crabs, copepods, shrimp, and squid. This paper reviews various features of the lipid molecular species of these animals. The results of the application of the lipidomic approach in ecology, embryology, physiology, lipid biosynthesis, and in studies on the nutritional value of marine invertebrates are also discussed. The possible applications of lipidomics in the study of marine invertebrates are considered.

Phospholipidomics quality evaluation of swimming crabs (Portunus trituberculatus) cultured with formulated feed, frozen trash fish, and mixed feed, a non-target approach by HILIC-MS

Swimming crab, Portunus trituberculatus, is popularly consumed because of its flavor and nutritional value. Herein, the crabs cultivated with formulated feed, frozen trash fish, and mixed feed were lipidomically analyzed by non-target HILIC-QTRAP/MS. The results showed that there were four phospholipid classes comprising 81 molecular species with plenty of polyunsaturated fatty acyl chains observed. The formulated feed group owned the highest content of phospholipids (332.91 μg·mg^-1), followed by the frozen trash fish group (294.74 μg·mg^-1) and mixed feed group (279.74 μg·mg^-1). The effect of feeding modes was compared statistically, and the most contributing variables of m/z 802 (PC 34:2), m/z 846 (ether PC o-38:1), m/z 792 (PE 40:5), etc. were screened out and verified. The phospholipidomics results indicated that the formulated feed could replace frozen trash fish for the cultivation of P. trituberculatus.

Latitudinal changes in the lipid content and fatty acid profiles of juvenile female red squat lobsters (Pleuroncodes monodon) in breeding areas of the Humboldt Current System

The red squat lobster Pleuroncodes monodon is a species of high commercial value that inhabits the Humboldt Current System. Along the Chilean coast, two populations are exploited by the fishing industry, one located off the coast of Coquimbo and the other off the coast of Concepción. Yet, it is unknown whether there are differences in the “bioenergetic fuel” (measured as lipid content and fatty acid profile) of juvenile populations of these two fishing units and whether these bioenergetic compounds can be modulated by differences in the environmental parameters (such as temperature or chlorophyll-a) of their breeding areas. To shed some light on this, we measured the lipid content and fatty acid profiles of the viscera and muscle of juvenile female red squat lobsters from these two fishing units, specifically from breeding areas near long-exploited fishing grounds: a) the northern fishing unit (NFU, from 26°S to 30°S) and b) the southern fishing unit (SFU, from 32°S to 37°S). We found differences in the lipid content, fatty acid profiles, and ratios of saturated fatty acids (C16:0/C18:0) of juvenile females from these two locations. In addition, the essential fatty acids (DHA/EPA) found in the viscera versus the muscle of these lobsters varied significantly. Juvenile females from the SFU (i.e. Concepción) showed a higher lipid content compared to the juvenile females from the NFU (i.e. Coquimbo). Consistently, individuals from the SFU had a higher content of fatty acids, which also proved to be richer in saturated and monounsaturated fatty acids compared to those from the NFU. Our results are important for the fisheries in both areas because these juvenile populations are the source of new recruits for the adult populations that are exploited by the fishing industry. Our study also aids in determining which populations are healthier or of better quality in bioenergetic terms. Furthermore, increasing the incorporation of bioenergetic parameters in fishery models is essential for the recruitment and stock assessment within an ecosystem approach, since it allows for the evaluation of the nutritional condition of different fishing populations.

First observation of seasonal variations in the meat and co-products of the snow crab (Chionoecetes opilio) in the Barents Sea

The snow crab (Chionoecetes opilio), SC, is a newly established species in the Barents Sea. The snow crab fishery has established itself as a new and profitable industry in Norway in the last decade. The fishery started as a year-round fishery, without any information of possible seasonal variations in the quality of the product. In 2017 a total allowable catch was established by the Norwegian government, and the fisheries were subsequently closed during the summer months. In order to optimize fishing times, and to evaluate this growing industry in the Barents Sea, seasonal variations of the meat content of the clusters, as well as variations in content and quality of co-products were investigated, aiming to identify the seasons where the exploitation of different products from SC can be most profitable. The results show seasonal variations in meat content and in composition of co-products. The highest co-product quantities and meat content are from February to April, followed by a period from June to September with decreasing meat and co-products. Our recommendation is to capture the SC in the winter-spring period in the Barents Sea, supporting the current situation and creating most value for the fisheries.

Temperature potentially induced distinctive flavor of mud crab Scylla paramamosain mediated by gut microbiota

Many factors affect the flavor of crabs. However, impact of temperature on flavor has not been reported. Here, we examined Scylla paramamosain collected within the main four producing areas in China from north sampling point (NP) and south sampling point (SP), respectively. The contents of flavouring-related substances in hepatopancreas, muscles and gonads were determined by high-performance liquid chromatography (HPLC). Meanwhile, high-throughput sequencing of 16S RNA gene was used to reveal the diversity distribution of gut microbiota at each sample collection point. Comparisons among flavor substances of edible parts, the implied higher temperature in SP may be beneficial to the accumulation of flavor substances in gonads, while lower temperature in NP may be beneficial to the accumulation of flavor substances in muscles and hepatopancreas. The gut microbiota of crabs, was analyzed via 16S rRNA gene sequencing. The results of gut microbiota showed that there were significant differences in the distribution of gut microbiota in NP and SP. The microbiota composition of SP has a high distribution richness and no absolute dominant bacteria, while NP has absolute dominant bacteria and its microbiota richness was lower than SP. The results of redundancy analysis (RDA) showed that there was a significant correlation between temperature and the relative abundance of gut microbiota, and a significant correlation between gut microbiota and the content of flavor substances. This study indicates that temperature may be one of the main factors for the differences of flavor substances between SP and NP, which was most probably mediated by gut microbiota. Further exploration is needed with laboratory experiments in which the environment is more precisely controlled if these views are to be determined.