Comparison of fatty acid and proximate compositions of the body and claw of male and female blue crabs (Callinectes sapidus) from different regions of the Mediterranean coast

Evaluation of fatty acid-related nutritional quality indices in processed and raw (Lethrinus lentjan) fish fillets

The Lethrinus lentjan fish is economically and nutritionally important in Iran. Therefore, knowledge of their chemical composition can help in the development of functional foods. In the present study, proximate and fatty acid compositions were determined in fresh and marinated Lethrinus lentjan fish. Fatty acids were identified by gas chromatography. The 24 pieces of fresh L. lentjan fish with an average weight of 470 ± 125 g were prepared. After removing wastes, the fish fillet was placed in a dish containing acetic acid, salt, garlic, and red pepper. The marinade product contained n-6PUFA (7.94%) and n-3PUFA (3.46%). The results showed that moisture content in the marinade sample decreased, while fat, protein, and ash contents increased and carbohydrate content was also decreased compared to the raw sample. The marinating process increased PUFA percentage (19.32%) and ratio of PUFA and SFA (0.61). The fresh and processed samples showed superior nutritional quality and the lowest h/H ratio, but AI and TI ratios were relatively favorable (p < .05). The thrombogenicity index (TI) (0.46) and atherogenicity index (AI) (3.56) were more than the recommended in terms of risk of coronary heart disease. It can be concluded that fresh and processed fish samples represent an excellent source of high-quality fat, demonstrating that this fish species' freshwater can be considered optimal for human consumption.

Evaluating the Performances of Interval Starting Accessibility Drying (ISAD) through Protein and Total Polyphenol Contents of Blue Crabmeat (Portunus segnis)

Blue crab (Portunus segnis) proliferation on Tunisian coasts started in 2014/2015. It has heavily impacted the balance of other species, local biodiversity, and fishing activity. Limiting these drawbacks may be achieved through ways promoting crabmeat. For this purpose, two different drying modes were tested: Conventional convective drying (CCD) and interval starting accessibility drying (ISAD) under 45 °C and relative humidity of 40%. Several air velocities were assayed under CCD: 1.5, 2.5, 3.5, and 5 m.s−1. Two different ISAD tests were run with different time-related conditions: drying period of 15 s and tempering period of 15 or 60 s. Drying modes and operating conditions performances were compared through proteins and total polyphenol contents (TPCs) evolution during the treatment. Important polyphenol and protein losses were observed between raw and processed crabmeat. Airflow velocities have a significant effect on crabmeat quality preservation. ISAD method under 15 s/60 s allowed the best preservation of these quality parameters. TPC and proteins losses and kinetics during drying under CCD or ISAD were modelled and correlations were established between the quality parameters, the residual water content at all drying times, and the evaporation rate.

Effects of dietary replacement of fish oil by vegetable oil on proximate composition and odor profile of hepatopancreas and gonad of Chinese mitten crab (Eriocheir sinensis)

Five different diets with different ratio of fish oil to vegetable oil were prepared. The biological index and proximate composition of Eriocheir sinensis fed with different diets were compared, and then sensory analysis, electronic nose (E-nose) and headspace-solid phase micro-extraction combined with gas chromatography-mass spectrometer (HS-SPME-GC-MS) analysis were applied to determine the odor profile of E. sinensis. The results showed that partial replacement (50%-75%) of fish oil by vegetable oil (FO/VO) was beneficial to the weight increment, nutrition accumulation, and odor-active compounds (OACs) formation of E. sinensis. A total of 7 and 11 OACs were detected in the hepatopancreas and gonad, respectively, these OACs contributed greatly to the overall odor profiles of E. sinensis when the dietary replacement levels were at 50% and 75%, respectively. The results could provide the guide for dietary fish oil replacement as well as improving the odor quality of E. sinensis. Practical application The objective of this research is to compare the effects of dietary replacement of fish oil by vegetable oil on proximate composition and odor profiles of E.sinensis. The results obtained from this study would not only chose an optimal dietary replacement level and serve as a useful database for the odor of female and crabs, but also provide some guide for the improvement of Chinese mitten crab aquaculture.

Mercury content of blue crabs (Callinectes sapidus) from southern New England coastal habitats: Contamination in an emergent fishery and risks to human consumers

Total mercury (Hg; ppm dry weight) was measured in blue crabs, Callinectes sapidus, collected from Narraganset Bay and adjacent coastal lagoons and tidal rivers (Rhode Island/Massachusetts, USA) from May to August 2006-2016. For juvenile crabs (21-79mm carapace width, CW), total Hg was significantly greater in chelae muscle tissue (mean±1 SD=0.32±0.21ppm; n=65) relative to whole bodies (0.21±0.16ppm; n=19), and irrespective of tissue-type, crab Hg was positively related to CW indicating bioaccumulation of the toxicant. Across a broader range of crab sizes (43-185mm CW; n=465), muscle Hg concentrations were significantly higher in crabs from the Taunton River relative to other locations (0.71±0.35ppm and 0.20±0.10ppm, respectively). Spatial variations in crab Hg dynamics were attributed to habitat-specific Hg burdens of their prey, including bivalves, gastropods, polychaetes, and shrimp. Prey Hg, in turn, was directly related to localized sediment Hg and methylmercury conditions. Biota-sediment accumulation factors for crabs and prey were negatively correlated with sediment organic content, verifying that organically-enriched substrates reduce Hg bioavailability. From a human health perspective, frequent consumption of crabs from the Taunton River may pose a human health risk (23% of legal-size crabs exceeded US EPA threshold level); thus justifying spatially-explicit Hg advisories for this species.

Insights into the prostanoid pathway in the ovary development of the penaeid shrimp Penaeus monodon

The prostanoid pathway converts polyunsaturated fatty acids (PUFAs) into bioactive lipid mediators, including prostaglandins, thromboxanes and prostacyclins, all of which play vital roles in the immune and reproductive systems in most animal phyla. In crustaceans, PUFAs and prostaglandins have been detected and often associated with female reproductive maturation. However, the presence of prostanoid biosynthesis genes remained in question in these species. In this study, we outlined the prostanoid pathway in the black tiger shrimp Penaeus monodon based on the amplification of nine prostanoid biosynthesis genes: cytosolic phospholipase A2, hematopoietic prostaglandin D synthase, glutathione-dependent prostaglandin D synthase, prostaglandin E synthase 1, prostaglandin E synthase 2, prostaglandin E synthase 3, prostaglandin F synthase, thromboxane A synthase and cyclooxygenase. TBLASTX analysis confirmed the identities of these genes with 51-99% sequence identities to their closest homologs. In addition, prostaglandin F2α (PGF2α), which is a product of the prostaglandin F synthase enzyme, was detected for the first time in P. monodon ovaries along with the previously identified PUFAs and prostaglandin E2 (PGE2) using RP-HPLC and mass-spectrometry. The prostaglandin synthase activity was also observed in shrimp ovary homogenates using in vitro activity assay. When prostaglandin biosynthesis was examined in different stages of shrimp ovaries, we found that the amounts of prostaglandin F synthase gene transcripts and PGF2α decreased as the ovaries matured. These findings not only indicate the presence of a functional prostanoid pathway in penaeid shrimp, but also suggest a possible role of the PGF2α biosynthesis in shrimp ovarian development.