Tânia Pimentel

Seafood traceability: current needs, available tools, and biotechnological challenges for origin certification

Market globalization and recurring food safety alerts have resulted in a growing consumer awareness of the need for food traceability. This is particularly relevant for seafood due to its perishable nature and importance as a key protein source for the population of the world. Here, we provide an overview of the current needs for seafood origin traceability, along with the limitations and challenges for its implementation. We focus on geochemical, biochemical, and molecular tools and how they should be optimized to be implemented globally and to address our societal needs. We suggest that seafood traceability is key to enforcing food safety regulations and fisheries control, combat fraud, and fulfill present and future expectations of conscientious producers, consumers, and authorities.

Potential use of fatty acid profiles of the adductor muscle of cockles ( Cerastoderma edule ) for traceability of collection site

Geographic traceability of seafood is key for controlling its quality and safeguarding consumers’ interest. The present study assessed if the fatty acid (FA) profile of the adductor muscle (AM) of fresh cockles (Cerastoderma edule) can be used to discriminate the origin of specimens collected in different bivalve capture/production areas legally defined within a coastal lagoon. Results suggest that this biochemical approach holds the potential to trace sampling locations with a spatial resolution <10 Km, even for areas with identical classification for bivalve production. Cockles further away from the inlet, i.e. in areas exposed to a higher saline variation, exhibited lower levels of saturated fatty acids, which are key for stabilizing the bilayer structure of cell membranes, and a higher percentage of polyunsaturated fatty acids, which enhance bilayer fluidity. Results suggest that the structural nature of the lipids present in the AM provides a stable fatty acid signature and holds potential for tracing the origin of bivalves to their capture/production areas.

Effect of chemical stress and ultraviolet radiation in the bacterial communities of zebrafish embryos

This study aimed to assess the effect of ultraviolet radiation (UVR) and chemical stress (triclosan-TCS; potassium dichromate-PD; prochloraz-PCZ) on bacterial communities of zebrafish (Danio rerio) embryos (ZEBC). Embryos were exposed to two UVR intensities and two chemical concentrations not causing mortality or any developmental effect (equivalent to the No-Observed-Effect Concentration-NOEC; NOEC diluted by 10-NOEC/10). Effects on ZEBC were evaluated using denaturing gradient gel electrophoresis (DGGE) and interpreted considering structure, richness and diversity. ZEBC were affected by both stressors even at concentrations/doses not affecting the host-organism (survival/development). Yet, some stress-tolerant bacterial groups were revealed. The structure of the ZEBC was always affected, mainly due to xenobiotic presence. Richness and diversity decreased after exposure to NOEC of PD. Interactive effects occurred for TCS and UVR. Aquatic microbiota imbalance might have repercussions for the host/aquatic system, particularly in a realistic scenario/climate change perspective therefore, future ecotoxicological models should consider xenobiotics interactions with UVR.

Bacterial communities 16S rDNA fingerprinting as a potential tracing tool for cultured seabass Dicentrarchus labrax

Traceability of seafood has become crucial with market globalization and consumer’s awareness. The present study used PCR-DGGE and 454 pyrosequencing to assess if bacterial communities fingerprint associated to seabass (Dicentrarchus labrax) skin mucus can be used to discriminate the geographic origin of fishes cultured in three semi-intensive fish farms. PCR-DGGE and pyrosequencing results were congruent and suggested that this molecular approach has the potential to trace fish farms with a spatial resolution <500 m. Pyrosequencing results provided a detailed insight into the bacterial community composition of seabass skin mucus and revealed the existence of a core of bacterial communities within family Pseudomonadaceae and Rhodobacteraceae. This approach also allowed to recognized key OTUs that are potentially relevant to discriminate the geographic origin of the fish being surveyed. Overall, the present study increased our knowledge on farmed seabass microbiome and demonstrated that specific and unique bacterial taxa can act as natural signatures that allow us to trace fish to its respective geographic origin. Our study provides valuable clues that should be more investigated in future studies as a way to fulfill current traceability needs in the global trade of seafood.

Spatio-temporal variability of trace elements fingerprints in cockle ( Cerastoderma edule ) shells and its relevance for tracing geographic origin

Understanding spatio-temporal variability of trace elements fingerprints (TEF) in bivalve shells is paramount to determine the discrimination power of this analytical approach and secure traceability along supply chains. Spatio-temporal variability of TEF was assessed in cockle (Cerastoderma edule) shells using inductively coupled plasma-mass spectrometry (ICP-MS). Four elemental ratios (Mg/Ca, Mn/Ca, Sr/Ca and Ba/Ca) were measured from the shells of specimens originating from eight different ecosystems along the Portuguese coast, as well as from four different areas, within one of them, over two consecutive years (2013 and 2014). TEF varied significantly in the shells of bivalves originating from the eight ecosystems surveyed in the present study. Linear discriminant function analyses assigned sampled cockles to each of the eight ecosystems with an average accuracy of 90%. Elemental ratios also displayed significant differences between the two consecutive years in the four areas monitored in the same ecosystem. Overall, while TEF displayed by cockle shells can be successfully used to trace their geographic origin, a periodical verification of TEF (>6 months and <1 year) is required to control for temporal variability whenever comparing specimens originating from the same area collected more than six months apart.