Transforming salmonid aquaculture from a consumer to a producer of long chain omega-3 fatty acids

Recommendations to endorse the sustainability of wild fish stock utilisation, supporting the health of marine ecosystems, are clashing with those to increase omega-3 fatty acids (n−3 LC-PUFA) consumption and promoting human health.

The objective of this study was to evaluate the role of salmonid aquaculture as a user or supplier of n−3 LC-PUFA, as a means of understanding the potential of the sector in conserving or depleting wild fisheries. A case-study feeding trial was implemented on rainbow trout up to commercial size, in which fish were fed a fish oil- or a linseed oil-diet. Harvested fish were analysed for fatty acid composition and difference and liking using consumers. The n−3 LC-PUFA input/n−3 LC-PUFA output ratio was computed. Consumers showed no preference, but were able to distinguish between samples. The fatty acids of the fillets were significantly modified by the diets. On the input side, for the production of 100 g of fish fillet, it was necessary to use 8.6 g of n−3 LC-PUFA to produce an output of 1.9 g of n−3 LC-PUFA in the fish oil-fed fish; in contrast it was only necessary to use 270 mg of n−3 LC-PUFA to produce 560 mg of these fatty acids in the linseed oil-fed fish. It was showed that the substitution of fish oil with linseed oil in aquafeed is an easily implemented tool to transform salmonids farming from a consumer into a net producer of health promoting n−3 LC-PUFA and accomplish its role in conserving wild fisheries in the future.

Dietary omega-3 fatty acids and depression in a community sample

To evaluate the association between omega-3 polyunsaturated essential fatty acids and depression, data regarding prevalence rates of self-reported depression and median daily dietary intakes of these fatty acids were obtained from an age-stratified, population-based sample of women (n = 755; 23-97 year) in the Barwon Statistical Division of south-eastern Australia. A self-report questionnaire based on Diagnostic and Statistical Manual-IV criteria was utilised to determine 12-month prevalence rates of depression in this sample, and data from biennial food frequency questionnaires examining seafood and fish oil consumption over a 6-year period were examined. Differences in median dietary intakes of omega-3 fatty acids between the depressed and nondepressed cohorts were analysed and results were adjusted for age, weight and smoking status. No significant differences in median intakes were identified between the two groups of women (median, interquartile range; depressed = 0.09g/day, 0.04-0.18 versus nondepressed = 0.11 g/day, 0.05-0.22, p = 0.3), although overall average intakes of omega-3 fatty acids were lower than recommended and rates of depression within this sample higher than expected, based on previous data. Further research that takes into account ratios of omega-6 to omega-3 polyunsaturated essential fatty acids, as well as other dietary sources of omega-3 fatty acids, is warranted.

Electrochemical metal ion sensors. Exploiting amino acids and peptides as recognition elements

Amino acids and peptides are known to bind metal ions, in some cases very strongly. There are only a few examples of exploiting this binding in sensors. The review covers the current literature on the interaction of peptides and metals and the electrochemistry of bound metal ions. Peptides may be covalently attached to surfaces. Of particular interest is the attachment to gold via sulfur linkages. Sulfur-containing peptides (eg cysteine) may be adsorbed directly, while any amino group can be covalently attached to a carboxylic acid-terminated thiol. Once at a surface, the possibility for using the attached peptide as a sensor for metal ions becomes realised. Results from the authors’ laboratory and elsewhere have shown the potential for selective monitoring of metal ions at ppt levels. Examples of the use of poly-aspartic acid and the copper binding peptide Gly-Gly-His for detecting copper ions are given.

Marine nutraceuticals : glucosomine and omega-3 fatty acids : new trends for established ingredients

Glucosamine and long-chain omega-3 lipid are the two most widely consumed marine nutracuticals. These   ingredients have been used as dietary supplement ingredients for many years, but  are now becoming important functional food and beverage ingredients. The production of GRAS and vegetarian glucosamine has led to increased use of this ingredient in beverages in particular. For long chain omega -3 lipid the development of stabilisation technologies has been critical for the increased use of these lipids in functional foods. The development of new sources of both of these ingredients, together with novel delivery and application technologies, will continue to drive increased consumption of these marine nutracuticals, in particular as functional food and beverage ingredients.

Proton transport properties in zwitterion blends with brønsted acids

We describe zwitterion, 3-(1-butyl-1H-imidazol-3-ium-3-yl)propane-1-sulfonate (Bimps), mixtures with 1,1,1-trifluoro-N-(trifluoromethylsulfonyl)methanesulfoneamide (HN(Tf)₂) as new proton transport electrolytes. We report proton transport mechanisms in the mixtures based on results from several methods including thermal analyses, the complex-impedance method, and the pulsed field gradient spin echo NMR (pfg-NMR) method. The glass transition temperature (Tg) of the mixtures decreased with increasing HN(Tf)₂ concentration up to 50 mol %. The Tg remained constant at −55 °C with further acid doping. The ionic conductivity of HN(Tf)₂ mixtures increased with the HN(Tf)₂ content up to 50 mol %. Beyond that ratio, the mixtures showed no increase in ionic conductivity (10⁻⁴ S cm⁻¹ at room temperature). This tendency agrees well with that of Tg. However, the self-diffusion coefficients obtained from the pfg-NMR method increased with HN(Tf)₂ content even above 50 mol % for all component ions. At HN(Tf)₂ 50 mol %, the proton diffusion of HN(Tf)₂ was the fastest in the mixture. These results suggest that Bimps cannot dissociate excess HN(Tf)₂, that is, the excess HN(Tf)₂ exists as molecular HN(Tf)₂ in the mixtures. The zwitterion, Bimps, forms a 1:1 complex with HN(Tf)₂ and the proton transport property in this mixture is superior to those of other mixing ratios. Furthermore, CH₃SO₃H and CF₃SO₃H were mixed with Bimps for comparison. Both systems showed a similar tendency, which differed from that of the HN(Tf)₂ system. The Tg decreased linearly with increasing acid content for every mixing ratio, while the ionic conductivity increased linearly. Proton transport properties in zwitterion/acid mixtures were strongly affected by the acid species added.

Dietary omega-3 fatty acids modify body fluid and cardiovascular homeostasis

Dietary omega-3 fatty acids are important for optimal nutrition. This research demonstrated the significant beneficial effects of these fatty acids on body fluid balance in aging and the regulation of blood pressure. A significant findng was that omega-3 fatty acids reduce neuro-inflammation (inflammation in the brain)

Stabilization of highly unsaturated fatty acids and delivery into foods

Highly unsaturated fatty acids derived from fish or algal oils, particularly EPA and DHA, are in high demand as healthy food ingredients in fortified foods. Due to their oxidative instability most food products incorporate stabilized microencapsulated EPA and DHA oils to avoid negative sensory impact associated with oxidation of these fatty acids. Complex coacervation has been particularly successful in stabilizing fish oil and providing an ingredient with a sensory shelf-life consistent with that of the food product. Overcoming the technical challenges associated with the instability of these oils will help drive growth of the omega-3 fortified healthy food ingredient market.

Solubilization of selected free fatty acids in palm oil by biodegradable ethoxylated surfactants

The solubilization of three major components, viz., palmitic, oleic, and linoleic acids, in palm oil by ethoxylated surfactants was investigated. The results were analyzed in terms of the molecular properties of surfactants and free fatty acids (FFAs). It was found that the solubilities of these FFAs in various micellar solutions depend not only on their octanol−water partition coefficients (Kow), but also on their physicochemical properties. The study on the solubilization kinetics was conducted by choosing palmitic acid as a model solubilizate and Tergitol 15-S-7 as the model surfactant. A first-order film diffusion model, which accounts for the direct uptake of organic molecules at a solid surface into surfactant micelles, was adopted to analyze the effect of surfactant on dissolution of palmitic acid. It was observed that the presence of surfactant reduced the mass-transfer coefficient. Instead, the overall mass-transfer rate was enhanced because of the much higher driving force from the increased solubilization capacity.

Differential mobilization of blubber fatty acids in lactating Weddell seals : evidence for selective use

A major source of energy during lactation in mammals is provided through the mobilization of blubber fatty acids (FAs). We investigated the extent to which FAs were mobilized to support both maternal metabolic requirements and milk production in the Weddell seal and how this was reflected in the FA composition of the pup’s blubber at the end of lactation (EL). FA composition of postpartum female blubber was similar in the 2 yr of study (2002 and 2003) but differed markedly by EL. Pup blubber FAs (at EL) were also different between years and did not match that of the mother’s milk or blubber. Milk FA composition changed during lactation, which may have been a reflection of an increase in pup energy demands at different stages of development. In addition, there was evidence of feeding by some females during lactation, with higher levels of some FAs in the milk than in the blubber. Our results indicate that differential mobilization of FAs occurred in lactating Weddell seals and that this was related to total body lipid stores at postpartum. Furthermore, growing pups did not store FAs unmodified, providing evidence that selective use does occur and also that using FA composition to elucidate dietary sources may be problematic in growing individuals.