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In this review, several chemical quality markers of Atlantic salmon, a widely farmed and consumed fish, are identified and discussed. Lipids, especially omega-3 fatty acids are of special importance as they relate to nutritional benefits. Pigmentation, resulting from the carotenoid deposition and retention in the muscles is one of the main factors that drive the market value of the fish. Both these quality markers are heavily influenced by the diet, and a variety of other important factors. Perhaps less obviously, contaminants and pollutants play a role in determining the overall quality of Atlantic salmon. Monitoring these quality parameters is performed via various analysis methods, many of which are considered industry standard due to many decades of producing reliable and accurate results. However, recent advances in spectroscopic techniques present faster, non-invasive techniques that have considerable potential in fisheries science. The following text outlines influences on the chemical quality markers in Atlantic salmon and compares various analysis techniques that can be used for quantification and monitoring. [ABSTRACT FROM AUTHOR]

Raman spectroscopy can be a useful tool for performing non-destructive subsurface measurements, allowing for investigations on intact foods that would otherwise require food products to be prepared for analysis, thus creating food waste, and often requiring the addition of chemicals. To overcome this, we have developed a method to measure the concentration of pigment (astaxanthin) and fatty acids in whole, unfilleted Atlantic salmon through the skin using defocused Raman spectroscopy. Subsurface measurements were performed across different regions of Atlantic salmon. PLS regression of the measured spectra gave a moderate correlation between Raman bands and astaxanthin concentration (R2 = 0.5797) and good correlations for fatty acid concentrations (total, saturated, monounsaturated, polyunsaturated, trans; R2 = 0.7457 to 0.8249). This work shows that subsurface Raman measurements can provide useful quantitative information regarding important quality parameters (pigment and fatty acid concentrations) that can aid with production in aquaculture. [ABSTRACT FROM AUTHOR]

Aquaculture represents a major part of the world's food supply. This area of food production is developing rapidly, and as such the tools and analytical techniques used to monitor and assess the quality of fish need to also develop and improve. The use of spatially off-set Raman spectroscopy (SORS) is particularly well-suited for these applications, given the ability of this technique to take subsurface measurements as well as being rapid, non-destructive and label-free compared to classical chemical analysis techniques. To explore this technique for analysing fish, SORS measurements were taken on commercially significant whole fish through the skin in different locations. The resulting spectra were of high quality with subsurface components such as lipids, carotenoids, proteins and guanine from iridophore cells clearly visible in the spectra. These spectral features were characterised and major bands identified. Chemometric analysis additionally showed that clear differences are present in spectra not only from different sections of a fish but also between different species. These results highlight the potential application for SORS analysis for rapid quality assessment and species identification in the aquaculture industry by taking through-skin measurements. [ABSTRACT FROM AUTHOR]