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Mussels’ aquaculture is one of the most important cultures in Europe, with a high level of self-sufficiency. In Spain, the main cultivated species is M. galloprovincialis, whose production takes place primarily in Galicia. In that region, a Protected Designation of Origin certification exists to certify the high quality of the product and its sustainability. This species is also present in other regions making the control of its traceability complicated. In order to distinguish Galician mussels from the others, the eukaryotes present in its digestive gland could be a useful tool. However, to use them as biomarkers, having an adapted protocol to recover the diversity present in the digestive gland is essential. In this work, we have selected a new protocol to optimize the study of the diversity of eukaryotes associated with the digestive gland of M. galloprovincialis. This protocol is based on a combination of a pre-treatment and a commercial DNA extraction kit, the amplification of DNA with two newly designed primer sets to avoid the DNA from the mussel, and the use of next-generation sequencing. The results showed a significant reduction of mussel DNA amplification and enough DNA quality for the subsequent sequencing, increasing the number of sequences recovered from other eukaryotes. This new protocol offers then a good chance to determine the diversity of eukaryotes present in the digestive gland of M. galloprovincialis, and it can be used in future studies to examinate the seasonal variation of the present species and to evaluate its potential as geographical traceability tool

Bioelectrical impedance analysis (BIA), near-infrared (NIR) spectroscopy and time domain reflectometry (TDR) were compared as non-destructive techniques, coupled with a classifier based on partial least square discriminant analysis (PLS-DA), to assess added water detection in a seafood model: tuna. Three classification models were developed for each technology in unfrozen, thawed and in a combination of both stages to distinguish between added and non-added water samples. Results were acceptable for the unfrozen stage with all the technologies, giving TDR the best performance (accuracy = 0.95; error rate = 0.06). However, results on the model for thawed stage were not satisfactory, due to the behavior of water during the freezing-thawing process in both types of samples (with and without added water). For the combined model, NIR failed in the classification (accuracy = 0.68; error rate = 0.32), BIA gave acceptable results (accuracy = 0.72; error rate = 0.28) and TDR made a good classification (accuracy = 0.87; error rate = 0.12)

Estudo para atopar diferenzas entre o rodaballo salvaxe e acuicultura atendendo os seguintes parámetros: Determinación dos valores de bioimpedancia (BIA), análises composición proximal do peixe, microbioma bacteriano do mucus, branquias e intestino, así como obter os datos biométricos dos individuos de estudo

The performances of three non-destructive sensors, based on different principles, bioelectrical impedance analysis (BIA), near-infrared spectroscopy (NIR) and time domain reflectometry (TDR), were studied to discriminate between unfrozen and frozen-thawed fish. Bigeye tuna (Thunnus obesus) was selected as a model to evaluate these technologies. The addition of water and additives is usual in the fish industry, thus, in order to have a wide range of possible commercial conditions, some samples were injected with different water solutions (based on different concentrations of salt, polyphosphates and a protein hydrolysate solution). Three different models, based on partial least squares discriminant analysis (PLS-DA), were developed for each technology. This is a linear classification method that combines the properties of partial least squares (PLS) regression with the classification power of a discriminant technique. The results obtained in the evaluation of the test set were satisfactory for all the sensors, giving NIR the best performance (accuracy = 0.91, error rate = 0.10). Nevertheless, the classification accomplished with BIA and TDR data resulted also satisfactory and almost equally as good, with accuracies of 0.88 and 0.86 and error rates of 0.14 and 0.15, respectively. This work opens new possibilities to discriminate between unfrozen and frozen-thawed fish samples with different non-destructive alternatives, regardless of whether or not they have added water.

The waste of fish resources constitutes a serious environmental problem that must be avoided. The valorisation of by-catch species and decreasing the discard rate constitute a more efficient and sustainable use of these marine biomasses. In this work, we characterize and propose different potential uses for Stromateus brasiliensis, another frequently discarded (≥ 90%) and poorly studied by-catch species captured in the South Atlantic Ocean (FAO 41) by trawler fishing fleets. Furthermore, in the case of this species, freezing and frozen storage of the whole fish is the only strategy currently employed for its exploitation. The results revealed that muscle from S. brasiliensis presented a high content of polyunsaturated fatty acids (20.34%) and that the concentrations of both total diacyl glyceryl ethers (2.41%) and heavy metals (Hg 0.038, Pb 0.006 and Cd 0.018 mg/kg) were below the established limits for safe human consumption. Likewise, the protein hydrolysates proved to be a good source of amino acids for human consumption or animal feeding. Minced muscle blocks could be made by a mechanical separation process of the flesh, and the composition of minced muscle did not differ much from that of the whole fish. Furthermore, this process allows the incorporation of cryoprotectants and antioxidants to extend the frozen shelf life of this fatty fish. An extraction process from mechanically mixed skin and bones yielded a good source of collagen that should not be neglected

The common octopus (Octopus vulgaris) is a highly valued cephalopod species which is marketed with different grades of processing, such as frozen, cooked or even canned, and is likely to be mislabeled. Some molecular methods have been developed for the authentication of these products, but they are either labor-intensive and/or require specialized equipment and personnel. This work describes a newly designed rapid, sensitive and easy-to-use method for the detection of Octopus vulgaris in food products, based on Recombinase Polymerase Amplification (RPA) and a detection using a Lateral Flow assay (LFA). After studying several gene markers, a system of primers and nfo-probe was designed in the COI (Cytochrome Oxidase I) region and was successfully tested in 32 reference samples (covering 14 species) and 32 commercial products, after optimization. The method was also validated in a ring trial with eight European laboratories and represents a useful tool for food authenticity control at all levels of the value chain

The increasing consumption of seafood products raised concerns over their sustainability and the conservation of marine resources. Seafood traceability, enabled by a regulated labelling system, is important to prevent overexploitation of these resources. Detailed seafood labels also help consumers to make informed choices about the products they purchase, enabling them to play a role in the conservation of marine resources. The regulations (EU) No.1169/2011 and (EU) No 1379/2013 are the European legislative tools that specify the mandatory information that must be present on seafood labels. The present study analysed the labels of seafood products found in fishmonger’s shops and supermarkets of different European countries in order to verify the presence of mandatory information required by the EU regulations currently in place

A handheld near infrared (NIR) spectroscopy device, with a wavelength range from 900 nm to 1650 nm and coupled with two Partial Least-Squares Discriminant Analysis (PLS-DA) models, has been used to demonstrate its applicability as a proof of concept for quality monitoring of bigeye tuna (Thunnus obesus). First, a classification model was created to discriminate between injected and non-injected tuna samples. Then, a second classification model was developed to discriminate between non-injected and each water and additives treatment used. The results were promising, showing both models good results in the validation dataset. The first model, with 8 latent variables (LV), had an error-rate of 0.08 and an accuracy value of 0.93. It showed a good discrimination between injected and non-injected samples. The second model, with 10 LV, presented an error rate of 0.15 and an accuracy of 0.88. The discrimination between treatments was good even when protein hydrolysate solutions were used (sensitivity = 0.81; specificity = 0.99; precision = 0.87), a case which is typically hard to detect with accurate destructive analysis. This work opens new possibilities for onsite inspection in the fish industry, where NIR could be used as a complementary tool for the detection of water solutions in tuna

Cephalopods are very relevant food resources. The common cuttlefish (Sepia officinalis) is highly appreciated by consumers and there is a lack of rapid methods for its authentication in food products. We introduce a new minor groove binding (MGB) TaqMan real-time PCR (Polymerase Chain Reaction) method for the authentication of S. officinalis in food products to amplify a 122 base pairs (bp) fragment of the mitochondrial COI (Cytochrome Oxidase I) region. Reference and commercial samples of S. officinalis showed a threshold cycle (Ct) mean of 14.40, while the rest of the species examined did not amplify, or showed a significantly different Ct (p < 0.001). The calculated efficiency of the system was 101%, and the minimum DNA quantity detected was 10−4 ng. No cross-reactivity was detected with any other species, thus, the designed method differentiates S. officinalis from other species of the genus Sepia and other cephalopod species and works for fresh, frozen, grilled, cooked and canned samples of Sepia spp. The method has proved to be reliable and rapid, and it may prove to be a useful tool for the control of fraud in cuttlefish products.

Fish wastage and market prices highly depend on accurate and reliable predictions of product shelf life and quality. The Quality Index Method (QIM) and EU grading criteria for whitefish (Council Regulation(EC) No 2406/96, 1996) are established sensory methods used in the market to monitor fish quality. Each assessment requires the consultation of a panel of trained experts. The indexes refer exclusively to the current state of the fish without any predictions about its evolution in the following days. This work proposes the development of a smart quality sensor which enables to measure quality and to predict its progress through time. The sensor combines information of biochemical and microbial spoilage indexes with dynamic models to predict quality in terms of the QIM and EU grading criteria. Besides, the sensor can account for the variability inside the batch if spoilage indexes are measured in more than one fish sample. The sensor is designed and tested to measure quality in fresh cod (Gadus morhua) under commercial ice storage conditions. Only two spoilage indexes, psychrotrophic counts and total volatile base-nitrogen content, were required to get accurate estimations of the two usual established sensory methods. The sensor is able to account for biological variability as shown with the validation and demonstration data sets. Moreover, new research and technologies are in course to make these measurements faster and non-destructive. This would allow having at hand a smart non-intrusive fish quality sensor

La pesquería artesanal del pulpo gallego apenas ha variado en el tiempo. La práctica habitual es el sacrificio del animal en el propio barco y el mantenimiento en agua de mar, de manera que el tiempo y las condiciones de acondicionamiento hasta el momento de la subasta en la lonja, es variable. En el pulpo refrigerado se estudiaron los atributos organolépticos diferenciadores de la frescura (apariencia, olor, color, brillo, estado de los ojos, presencia de limo, ventosas, etc.), la composición, las variables físico-químicas (pH y contenido de nitrógeno de bases volátiles totales), la alteración bacteriana (recuento total de unidades formadoras de colonias) así como los atributos del producto cocinado (olor, color, sabor y textura). Los resultados ponen de manifiesto que la práctica de eviscerar a bordo de los barcos no es la mejor opción si las condiciones de almacenamiento posteriores no son las adecuadas. En las muestras de pulpo sin eviscerar, si los órganos internos no son dañados en el sacrificio y las temperaturas de almacenamiento se mantienen bajas, para periodos cortos de conservación en cámara refrigerada, la presencia de vísceras no llega a influir negativamente en la calidad. Las muestras evisceradas en la lonja, si posteriormente se almacenan inmediatamente en frío, podría ser una práctica adecuada