Composition of lipids and proteins of several species of molluscs, marine and terrestrial, from the Adriatic Sea and Serbia

Protein quality of commercially important edible bivalves

Bivalves are a high-quality source of animal protein for human consumption. In recent years, the demand for bivalve proteins has increased dramatically, leading to a sharp increase in global production of marine bivalves. To date, although the amino acid profiles of many bivalves have been reported, such information has not been well organized. Therefore, there is an urgent need for a comprehensive scientific review of the protein quality of bivalves, especially commercially important edible bivalves. In this context, this study was conducted to evaluate the protein quality of commercially important edible bivalves. In general, most bivalves are rich in protein (> 50% of their dry weight) and amino acids (> 30 g/100g protein). Although most species of bivalves are rich in essential amino acids (EAA) (up to 50 g/100g protein), some species of edible bivalves have very low levels of EAA (< 5 g/100g protein). Based on the AA score, almost all bivalves have at least two limiting AAs. Most bivalve proteins provides delicious flavors with unami, sweetness and a hint of bitterness. The findings of this study not only serve as a a guide for selecting appropriate bivalves based on consumer preferences for specific AAs or AA scores, but also provide information on potential bivalve species for aquaculture to produce higher protein quality to meet the growing demand for high quality animal protein.

Edible Snail Production in Europe

Simple Summary

Edible snails are a good source of easily digestible nutrients. They are easy to breed and their farming is more environmentally friendly than traditional livestock: they need little space, use less feed per kg of growth, and emit significantly less greenhouse gases. This review aims to present the most important issues related to the breeding of edible snails in European conditions: their importance, maintaining systems, the value of meat and caviar, and the feed used during the animals’ rearing and fattening period.

Abstract

The human population is growing; food production is becoming insufficient, and the growing awareness of the negative impact of traditional animal husbandry on the environment means that the search for alternative methods of providing animal protein is continuously underway. The breeding of edible snails seems to be a promising option. The most popular species of edible snails in Europe include the brown garden snail Cornu aspersum (Müller, 1774) (previously divided into two subspecies: Cornu aspersum aspersum (Müller, 1774) and Cornu aspersum maxima (Taylor, 1883)), as well as the Roman Snail—Helix pomatia Linnaeus, 1758. These animals are highly productive, require relatively little space, are easy to breed and their maintenance does not require large financial outlays. This review focuses on the prospects of food snail farming in Europe. It discusses the living conditions, the nutritional value of the snails’ meat, and the way of feeding the animals, paying particular attention to issues still not scientifically resolved, such as the need for micro and macro elements, as well as fat and carbohydrates.

Multicentury perspective assessing the sustainability of the historical harvest of seaducks

Where available, census data on seabirds often do not extend beyond a few years or decades, challenging our ability to identify drivers of population change and to develop conservation policies. Here, we reconstruct long-term population dynamics of northern common eiders (Somateria mollissima borealis). We analyzed sterols together with stable nitrogen isotopes in dated pond sediment cores to show that eiders underwent broadscale population declines over the 20th century at Canadian subarctic breeding sites. Likely, a rapidly growing Greenland population, combined with relocation of Inuit to larger Arctic communities and associated increases in the availability of firearms and motors during the early to mid-20th century, generated more efficient hunting practices, which in turn reduced the number of adult eiders breeding at Canadian nesting islands. Our paleolimnological approach highlights that current and local monitoring windows for many sensitive seabird species may be inadequate for making key conservation decisions.

Fatty Acid Profile in Fat Obtained from Edible Part of Land Snails Harvested in Poland

Introduction

The objective was to determine the content of fatty acids in edible snail fat by snail species, collection site, and processing stage.

Material and Methods

The research material comprised 180 edible fat samples from the three genera of edible snails collected in Poland: free-living Helix pomatia (HP) and two cultivated Cornu subspecies: C. aspersa maxima (CAM) and C. aspersum aspersum (CAA). All snails came from the Greater Poland and Lower Silesian Provinces: HP from their natural habitat and CAM and CAA from heliciculture farms. The studies focused on the raw meat, cooked meat, and frozen meat processing stages. Fatty acid (FA) profiles were determined by the gas chromatography method.

Results

Helix pomatia fat showed a higher saturated fatty acid (SFA) content, whereas the fat of Cornu genus snails had a higher unsaturated fatty acid (UFA) component, i.e. monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA). Thermal processing of snail meat increased all the determined SFA and decreased all the PUFA values, and increased the content of C18:1, C20:1, and C22:1 acids in the MUFA group. The material collection site had limited impact on FA content as differences were noted only in levels of C18:1, C18:2 n6, and C20:5. The differences pertained only to the fat of farmed snails of the Cornu genus.

Conclusion

Due to the high content of UFA and a favourable ratio of n6:n3 acids and PUFA:SFA, snail fat can be regarded as nutritionally valuable.

Nutritional composition and total collagen content of two commercially important edible bivalve molluscs from the Sea of Japan coast

The study aimed to evaluate the chemical composition and nutraceutical potential of two commercially significant edible bivalve mollusc species (Anadara broughtonii and Mactra chinensis). The edible parts (motor muscle, mantle and adductor) of these molluscs were analyzed for their proximate composition, collagen content, amino acid profile, chemical score and elemental constituents. Both molluscs had low fat content (2.43–6.91 g/100 g dry weight), and protein (55.36–68.01 g/100 g dry weight) and carbohydrates (11.36–20.37 g/100 g dry weight) were their main components. Total collagen content of the edible bivalve molluscs varied from 30.5 to 39 mg/g wet weight, accounting for approximately half of their total protein content. Among amino acids, glycine, glutamate, aspartic acid, alanine, leucine, lysine and arginine were present at high levels in the edible parts of both bivalve molluscs, while the major elements present were sodium, potassium, magnesium, calcium, iron, zinc and nickel. Having high-quality protein content, edible bivalve molluscs could be excellent sources of nutritive ingredients and, after further study, may find applications in nutricosmetics and functional foods.

Polyunsaturated fatty acids from Phyllocaulis boraceiensis mucus block the replication of influenza virus

Influenza viruses cause worldwide outbreaks and pandemics in humans and animals every year with considerable morbidity and mortality. The molecular diversity of secondary metabolites extracted from mollusks is a good alternative for the discovery of novel bioactive compounds with unique structures and diverse biological activities. Phyllocaulis boraceiensis is a hermaphroditic slug that exudes mucus, in which was detected hydroxy polyunsaturated fatty acids that exhibited potent antiviral activity against measles virus. The objective of this study was to evaluate this property against Influenza viruses. Cell viability and toxicity of the mucus were evaluated on Madin-Darby canine kidney (MDCK) cells by MTT assay. Antiviral activity from mucus against influenza viruses was carried out by determination of the virus infection dose and by immunofluorescence assays. The crude mucus and its fractions exhibited low cytotoxicity on MDCK cells. A significant inhibition of viral replication, reduced by the order of eight times, was observed in influenza-induced cytopathic effect. In immunofluorescence assay was observed a decrease of more than 80% of the viral load on infected MDCK cell treated with mucus and its fractions. The viral glycoproteins hemagglutinin and neuraminidase located on the surface of the virus are crucial for the replications and infectivity of the influenza virus. Some authors demonstrated that lipids, such as, polyunsaturated fatty acids exhibited multiple roles in antiviral innate and adaptive responses, control of inflammation, and in the development of antiviral therapeutics. As corroborated by other studies, hydroxy polyunsaturated fatty acids interfered with the binding of influenza virus on host cell receptor and reduced viral titers. The results obtained indicated that polyunsaturated fatty acids from P. boraceiensis crude mucus and fractions 39 exerted antiviral activity against influenza virus.

Proximate composition, amino acid and fatty acid profiles of marine snail Rapana venosa meat, visceral mass and operculum

BACKGROUND

Rapana venosa (Rv), an important marine snail, demonstrates an increasing nutritional and economic importance. However, there is still limited information available on their nutritional composition. The present study highlights and provides new information on the proximate composition, amino acid and fatty acid profiles of different body parts of Rv, aiming for its better application and research.

RESULTS

The operculum contained a high amount of protein and flavor amino acids. The edible tissues, including meat and visceral mass, were valuable sources of essential amino acids (EAA) apart from methionine and cysteine. In addition, the meat contained high amount of taurine. Fatty acid analysis indicated that the edible tissues contained high amounts of ω3 fatty acids, especially eicosapentaenoic acid (EPA) (C20:5ω3) and docosahexaenoic acid (DHA) (C22:6ω3), and had a low ω6/ω3 fatty acid ratio. Interestingly, significantly higher concentrations of most nutritional elements such as fat, EAA, EPA and DHA, were found in the visceral mass compared to those in the meat.

CONCLUSION

The operculum of Rv may became a very interesting source for some protein and flavor peptide development, and the edible parts of Rv may be utilized for special dietary applications requiring high amounts of taurine, EPA, DHA and a lower ω6/ω3 fatty acid ratio. © 2017 Society of Chemical Industry.

Direct infusion mass spectrometric identification of molecular species of glycerophospholipid in three species of edible whelk from Yellow Sea

Whelk has been exploited commercially as a delicacy for a long time. Although previous studies have suggested that whelk might serve as a potential rich source of long chain omega-3 polyunsaturated fatty acids (n-3 LC-PUFA) enriched phospholipid (PL), the molecular species profile of the PL have not been reported yet. In this study, more than 220 molecular species of glycerophospholipid (GP) belonging to eight classes including glycerophosphocholine, glycerophosphoethanolamine, glycerophosphoserine, glycerophosphoinositol, lysoglycerophosphocholine, lysoglycerophosphoethanolamine, lysoglycerophosphoserine and lysoglycerophosphoinositol in three species of edible whelks (Buccinium yokomaruae, Neptunea arthritica cumingi Cosse and Volutharpa ampullaceal) were identified for the first time by using direct infusion tandem mass spectrometric method. Most of the predominant GP molecular species contained n-3 LC-PUFA, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Meanwhile, the whelk lipids contained a high proportion of PL (32.92-55.55% of total lipids) and PUFA (30.45-41.42% of total FA). Among PL, phosphatidylcholine (44.18-65.49mol%) was dominant.

Nutrient composition of the marine snail (Hexaplex trunculus) from the Tunisian Mediterranean coasts

BACKGROUND

Marine snail (Hexaplex trunculus) presents increasing nutritional, commercial and economical importance, being widely consumed in northern Africa, particularly in Mediterranean countries. From a nutritional point of view there is still limited information on the chemical composition of edible tissues (meat and hepatopancreas) of this species. Therefore, the aims of the present work were to study the proximate chemical composition, fatty acid and amino acid profiles of H. trunculus from the Tunisian Mediterranean coasts.

RESULTS

Fatty acid profiles showed that the polyunsaturated fatty acids (PUFA) content is higher than the saturated fatty acids (SFA). The yields of PUFA and SFA present in the meat fat were 68.2% and 33.4% of the total fatty acids, respectively. Similar values were obtained in the hepatopancreatic lipidic fraction. Snail tissues contain valuable concentrations of PUFA, especially n-6 and n-3 with chain lengths of 20 and 22 carbons. All edible tissues were valuable sources of essential amino acids. Aspartic acid is the major amino acids present in the meat and hepatopancreas. The concentrations of nutrients were also determined in the hepatopancreas and meat of H. trunculus. Significantly high concentrations of minerals and trace elements were found in these tissues.

CONCLUSION

This study suggests that H. trunculus is an important source of protein and essential amino acids. Furthermore, the snail lipidic fraction contains high proportions of polyunsaturated fatty acids benefical for human health.

Quantification of in situ nutrient and heavy metal remediation by a small pearl oyster (Pinctada imbricata) farm at Port Stephens, Australia

The use of pearl oysters has recently been proposed as an environmental remediation tool in coastal ecosystems. This study quantified the nitrogen, phosphorus and heavy metal content of the tissue and shell of pearl oysters harvested from a small pearl oyster farm at Port Stephens, Australia. Each tonne of pearl oyster material harvested resulted in approximately 703 g metals, 7452 g nitrogen, and 545 g phosphorus being removed from the waters of Port Stephens. Increasing current farm production of 9.8 tyr(-1) to 499 tyr(-1) would balance current nitrogen loads entering Port Stephens from a small Sewage Treatment Plant (STP) located on its southern shores. Furthermore, manipulation of harvest dates to coincide with oyster condition would likely remove substantially greater quantities of nutrients. This study demonstrates that pearl aquaculture may be used to assist in the removal of pollutants from coastal waters while producing a commercially profitable commodity.

Pearl aquaculture-profitable environmental remediation?

Bivalve molluscs are filter feeders, with pearl oysters able to filter water at rates up to 25 lh(-1)g(-1) of dry wt. tissue. Since this process leads to rapid bioaccumulation of recalcitrant pollutants such as heavy metals, organochlorine pesticides and hydrocarbons from impacted sites, it has prompted the widespread use of molluscs as biomonitors to quantify levels of marine pollution. This paper proposes pearl oyster deployment as a novel bioremediation technology for impacted sites to remove toxic contaminants, reduce nutrient loads and lower concentrations of microbial pathogens. Estimates extrapolated from the literature suggest that a modest pearl oyster farm of 100 t oyster material per year could remove 300 kg heavy metals plus 24 kg of organic contaminants via deposition into the tissue and shell. Furthermore, it was estimated that up to 19 kg of nitrogen may be removed from the coastal ecosystem per tonne of pearl oyster harvested. Pearl oysters are also likely to filter substantial amounts of sewage associated microbial pathogens from the water column. Method of cultivation and site selection are the key to minimising negative environmental impacts of bivalve cultivation. Deployment of oysters at sites with high nutrient and contaminant loadings would be advantageous, as these compounds would be removed from the ecosystem whilst generating a value-added product. Future potential may exist for harvesting bio-concentrated elements for commercial production.