Violetta Aru

Metabolomics analysis of shucked mussels’ freshness

In this work a NMR metabolomics approach was applied to analyze changes in the metabolic profile of the bivalve mollusk Mytilus galloprovincialis upon storage at 0°C and 4°C for 10 and 6 days, respectively. The most significant microbial groups involved in spoilage of mussels were also investigated. The time-related metabolic signature of mussels was analysed by Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA) which revealed a clear discrimination between the fresh samples and those stored at 0°C and 4°C. The results evidenced a noticeable increase in acetate, lactate, succinate, alanine, branched chain amino acids, trimethylamine and a progressive decline of osmolytes like betaine, homarine and taurine during storage. Exploration of the correlations of these metabolites with microbial counts suggested their use as potential biomarkers of spoilage. The results support the use of NMR metabolomics as a valuable tool to provide information on seafood freshness.

Data on the changes of the mussels' metabolic profile under different cold storage conditions

One of the main problems of seafood marketing is the ease with which fish and shellfish undergo deterioration after death. 1H NMR spectroscopy and microbiological analysis were applied to get in depth insight into the effects of cold storage (4 °C and 0 °C) on the spoilage of the mussel Mytilus galloprovincialis. This data article provides information on the average distribution of the microbial loads in mussels׳ specimens and on the acquisition, processing, and multivariate analysis of the 1H NMR spectra from the hydrosoluble phase of stored mussels. This data article is referred to the research article entitled “Metabolomics analysis of shucked mussels’ freshness” (Aru et al., 2016) [1].

Changes in the 1H NMR Metabolic Profile of Mussels (Mytilus Galloprovincialis) with Storage at 0°C

Mussels are rich in minerals and vitamins and mussel fat is rich in polyunsaturated fatty acids which are biologically important and have been associated with a decreased risk of cardiovascular disease. Although mussels are available in the market, most are kept alive on ice or refrigerated (2–4°C) until consumed. The shelf life of mussels is limited, primarily due to a variety of microbial and biochemical degradation mechanisms depending on the duration and conditions of storage as well as the initial quality of the product. There are many well established traditional analytical techniques and methods available to assess the quality of seafood, including sensory evaluation based on quality index method, microbial inspection based on total viable counts, biochemical methods related, and proteome analysis. Although chemical and microbiological methods are useful both for research and product development, they are not practical for routine use, as they require expensive laboratory equipment and trained staff, are destructive, and can be labor intensive and time consuming. Nuclear Magnetic Resonance (NMR) spectroscopy is a technique able to provide detailed chemical information on a wide range of compounds simultaneously present in a sample. In combination with multivariate analysis, NMR is recognize to make available relevant information on the composition of food in many area of food science such as foodstuffs quality, raw material safety, and authentication. The goal of this work was to investigate the NMR metabolic changes in the aqueous extracts of Mytilus galloprovincialis samples stored at 0° over a period of 7 days and to find putative metabolites-markers influenced by the conservation conditions.

Cool-Climate Red Wines—Chemical Composition and Comparison of Two Protocols for 1H–NMR Analysis

This study investigates the metabolome of 26 experimental cool-climate wines made from 22 grape varieties using two different protocols for wine analysis by proton nuclear magnetic resonance (1H-NMR) spectroscopy. The wine samples were analyzed as-is (wet) and as dried samples. The NMR datasets were preprocessed by alignment and mean centering. No normalization or scaling was performed. The “wet” method preserved the inherent properties of the samples and provided a fast and effective overview of the molecular composition of the wines. The “dried” method yielded a slightly better sensitivity towards a broader range of the compounds present in wines. A total of 27 metabolites including amino acids, organic acids, sugars, and alkaloids were identified in the 1H-NMR spectra of the wine samples. Principal component analysis was performed on both NMR datasets evidencing well-defined molecular fingerprints for ‘Baco Noir’, ‘Bolero’, ‘Cabernet Cantor’, ‘Cabernet Cortis’, ‘Don Muscat’, ‘Eszter’, ‘Golubok’, ‘New York Muscat’, ‘Regent’, ‘Rondo’, ‘Triomphe d’Alsace’, ‘Précose Noir’, and ‘Vinoslivy’ wines. Amongst the identified metabolites, lactic acid, succinic acid, acetic acid, gallic acid, glycerol, and methanol were found to drive sample groupings. The 1H-NMR data was compared to the absolute concentration values obtained from a reference Fourier transform infrared method, evidencing a high correlation.

Sediments distribution of trace metals in a coastal lagoon (Southern Sardinia, Mediterranean Sea): assessment of contamination and ecological risk

ABSTRACT Coastal lagoons are subject to several sources of contaminations. To shade light on the contamination level of the Santa Gilla lagoon (Tyrrhenian Sea) we investigated the spatial distribution of Cr, Ni, Pb, Zn and Hg in sediments and their correlation with grain size and organic matter contents. Moreover, sediment contamination levels and the ecological risk associated with metal concentration were assessed using different abiotic indicators. The lagoon is characterised by low levels of contamination, with exceptions for Pb and Hg, whose distribution reflects the position of an old chlor-alkali plant and that of an airport. These results indicate that the restoration put in place 30 years ago have not reached the expected target and that the presence of the airport deserves further attention. In the outer section of the lagoon, where clam fishery occurs, we observed low levels of contamination suggesting that such artisanal fishery could somehow help mobilising metals. We conclude that the area exposed to Hg pollution, though tentatively restored, still suffers of a potential risk of ecosystem deterioration. We pinpoint that further investigations on the mobility, bioavailability and toxicity of metals are needed to finally address the actual impairment of the Santa Gilla lagoon.

The Effect of Season on the Metabolic Profile of the European Clam Ruditapes decussatus as Studied by 1H-NMR Spectroscopy

In this study, the metabolome of Ruditapes decussatus, an economically and ecologically important marine bivalve species widely distributed in the Mediterranean region, was characterized by using proton Nuclear Magnetic Resonance (1H-NMR) spectroscopy. Significant seasonal variations in the content of carbohydrates and free amino acids were observed. The relative amounts of alanine and glycine were found to exhibit the same seasonal pattern as the temperature and salinity at the harvesting site. Several putative sex-specific biomarkers were also discovered. Substantial differences were found for alanine and glycine, whose relative amounts were higher in males, while acetoacetate, choline and phosphocholine were more abundant in female clams. These findings reveal novel insights into the baseline metabolism of the European clam and represent a step forward towards a comprehensive metabolic characterization of the species. Besides providing a holistic view on the prominent nutritional components, the characterization of the metabolome of this bivalve represents an important prerequisite for elucidating the underlying metabolic pathways behind the environment-organism interactions.