Seasonal variations of fatty acid compositions in various Korean shellfish

Isolation of fast-growing thraustochytrids and seasonal variation on the fatty acid composition of thraustochytrids from mangrove regions of Navi Mumbai, India

This study was aimed to isolate fast-growing thraustochytrids and the influence of seasonal variation in fatty acid composition from the mangrove habitat. The thraustochytrids were isolated from fallen yellowish or green mangrove leaves, in four seasons, including winter, summer, rainy, and post rainy season in one year. The thraustochytrids were analyzed for biomass production, total lipid content, and fatty acid profile. The thraustochytrid isolates showed biomass yield and total lipid content in the range of 14.12 ± 0.69 to 22.98 ± 0.53 g/L and 34.98-58.86% per dry cell weight, respectively. The isolates showed two dominant fatty acids, palmitic acid (PA) as saturated fatty acid (SFA) and docosahexaenoic acid (DHA) as long-chain polyunsaturated fatty acids (LC-PUFA) in total fatty acid (TFA) content. The significant differences (P < 0.05) were observed for seasonal variations in SFA and DHA content in summer isolates and winter isolates. The maximum DHA content with 47.12% of TFA, recorded in winter (January) isolates and summer (April) isolates with SFA 68.82% of TFA. The results from this study were verified the hypothesis that the presence of high DHA producing thraustochytrids in lower temperature season in the same habitat. These findings have also emphasized the role of the environmental temperature conditions and the importance of thraustochytrid fatty acid composition as a dietary biomarker. Also, it revealed the ecological significance of thraustochytrid in DHA enrichment in the food web of the marine ecosystem. These findings could be useful while isolating thraustochytrids according to seasons for industrial application for omega 3 fatty acids and biodiesel production.

Shellfish: Nutritive Value, Health Benefits, and Consumer Safety

Shellfish is a major component of global seafood production. Specific items include shrimp, lobsters, oysters, mussels, scallops, clams, crabs, krill, crayfish, squid, cuttlefish, snails, abalone, and others. Shellfish, in general, contain appreciable quantities of digestible proteins, essential amino acids, bioactive peptides, long-chain polyunsaturated fatty acids, astaxanthin and other carotenoids, vitamin B₁₂ and other vitamins, minerals, including copper, zinc, inorganic phosphate, sodium, potassium, selenium, iodine, and also other nutrients, which offer a variety of health benefits to the consumer. Although shellfish are generally safe for consumption, their exposure to diverse habitats, the filter feeding nature of shellfish such as oysters, clams, and mussels, and unhealthy farming and handling practices may occasionally entail health risks because of possible presence of various hazards. These hazards include pathogenic organisms, parasites, biotoxins, industrial and environmental pollutants, heavy metals, process-related additives such as antibiotics and bisulfite, and also presence of allergy-causing compounds in their bodies. Most of the hazards can be addressed by appropriate preventive measures at various stages of harvesting, farming, processing, storage, distribution, and consumption. Furthermore, consumer safety of shellfish and other seafood items is strictly monitored by international, governmental, and local public health organizations. This article highlights the nutritional value and health benefits of shellfish items and points out the various control measures to safeguard consumer safety with respect to the products.

Comparison of lipid content and Fatty Acid composition in the edible meat of wild and cultured freshwater and marine fish and shrimps from china

The lipid content and fatty acid composition in the edible meat of twenty-nine species of wild and cultured freshwater and marine fish and shrimps were investigated. Both the lipid content and fatty acid composition of the species were specified due to their unique food habits and trophic levels. Most of the marine fish demonstrated higher lipid content than the freshwater fish, whereas shrimps had the lowest lipid content. All the marine fish and shrimps had much higher total n-3 PUFA than n-6 PUFA, while most of the freshwater fish and shrimps demonstrated much lower total n-3 PUFA than n-6 PUFA. This may be the biggest difference in fatty acid composition between marine and freshwater species. The cultured freshwater fish demonstrated higher percentages of total PUFA, total n-3 PUFA, and EPA + DHA than the wild freshwater fish. Two freshwater fish, including bighead carp and silver carp, are comparable to the marine fish as sources of n-3 PUFA.

Seasonal variation in nutrient composition of Mytilus coruscus from China

Seasonal variation in the nutrient composition of Mytilus coruscus (thick shell mussel), cultivated in Shengsi Islands, Zhejiang Province, China, was investigated in this study. Proximate composition, mineral and amino acid concentrations, as well as the compositions of the lipid and fatty acid of thick shell mussels were analyzed. Proximate composition and mineral contents were seasonally varied significantly except for calcium (Ca) and lead (Pb). Glycine was the predominant amino acid in mussels throughout all seasons, while lysine, threonine, phenylalanine, and arginine were the main essential amino acids. The predominant lipids were phospholipids, followed by triacylglycerols and sterol esters. Polyunsaturated fatty acids (PUFA) predominated over saturated and monounsaturated fatty acids throughout the year. Docosahexaenoic acid (12.44-18.34% of total fatty acids) and eicosapentaenoic acid (10.79-14.60%) were the most abundant PUFA. Significant seasonal variations were observed in the compositions of most amino acids, lipid classes, and fatty acids. Cultivated Chinese thick shell mussels represent a source of the health benefiting long chain n-3 PUFA, essential amino acids, and minerals for human consumption.

Solid-phase extraction and liquid chromatography–mass spectrometry for the determination of free fatty acids in shellfish

A novel analytical protocol for the determination of free fatty acids (FFAs; saturated, monounsaturated and polyunsaturated) in shellfish using electrospray ionisation and liquid chromatography-mass spectrometry (LC-MS) is described. Total lipids were extracted from four commercially important shellfish species using chloroform-methanol in a modification of the traditionally used Bligh and Dyer method. FFAs were recovered from lipidic shellfish extracts by solid-phase extraction (SPE) on an aminopropyl-silica column using a 98:2 v/v diethyl ether (DEE)-acetic acid solution. Ether extracts containing the FFAs were evaporated and reconstituted in 70:30 v/v methanol-chloroform before analysis by LC-MS. The limits of quantification (LOQs) of the method ranged from 60 to 560 microgg(-1) wet weight depending on the different FFAs determined with selected ion monitoring (SIM). Results demonstrate that LC-MS is well suited for identification and quantification of FFAs in shellfish and negates the use of sample derivatisation required in gas chromatographic analysis.

Estimation of daily exposure to 4-hydroxy-2-alkenals in Korean foods containingn-3 andn-6 polyunsaturated fatty acids

4-Hydroxy-2-alkenals are cytotoxic aldehydes generated from the oxidation of n-3 and n-6 polyunsaturated fatty acids. The compounds have shown various biological effects via Schiff base adducts or Michael addition adducts at levels higher than physiological ones. To assess human exposure to 4-hydroxy-2-alkenals in the diet, 4-hydroxy-2-alkenals in vegetable oils, fish and shellfish were monitored using GC/MS/SIM. 2001 National Health and Nutrition Survey (2002) data were employed for the dietary intake pattern. The Korean daily exposure to 4-hydroxy-2-alkenals, excluding a possible one from fried food, was 4.3 microg day-1, constituted of 1.6 microg 4-hydroxy-2-hexenal (HHE) and 2.7 microg 4-hydroxy-2-nonenal (HNE). It was calculated that Koreans could be additionally exposed to more than 11.8 microg day-1 4-hydroxy-2-alkenal from fried foods. Thus, the combined exposure would be 16.1 microg day-1, which corresponds to 0.3 microg kg-1 body weight day-1 for a 60 kg Korean adult. In spite of the biological toxicity of 4-hydroxy-2-alkenals, the risk for human could not be quantified due to the lack of a virtually safe dose of the compounds. However, considering the basal level of 4-hydroxy-2-alkenals in many tissues, the present value from the diet may not pose a significant risk for human health.