Occurrence of microplastics and metals in European seabass produced in different aquaculture systems: Implications for human exposure, risk, and food safety.

Microplastics (MPs) are emerging contaminants of increasing concern as they may cause adverse effects and carry other contaminants, which may potentially compromise human health. Despite occurring in aquatic ecosystems worldwide, the knowledge about MP presence in different aquaculture systems and their potential impact on seafood products is still limited. This study aimed to determine the levels of MPs in water, feed, and European seabass (Dicentrarchus labrax) from three relevant aquaculture systems and estimate human exposure to MPs and metals through seabass consumption. The recirculating aquaculture system (RAS) had the highest MP occurrence in water and feed. MP levels in seabass followed the aquaculture system's levels in water and feed, with RAS-farmed fish presenting the highest MP load, both in the fish gastrointestinal tract (GIT) and muscle, followed by pond-, and cage-farmed fish. MPs' characteristics across aquaculture systems and fish samples remained consistent, with the predominant recovered particles falling within the MP size range. The particles were visually characterized and chemically identified by micro-Fourier Transform Infrared Spectroscopy (µFTIR). Most of these particles were fibres composed of man-made cellulose and PET. MP levels in GIT were significantly higher than in muscle for pond- and RAS-farmed fish, MPs' bioconcentration factors >1 indicated bioconcentration in farmed seabass. Metal concentrations in fish muscle were below permissible limits, posing low intake risks for consumers according to the available health-based guidance values and estimated dietary scenarios.

Enhancing the authenticity of animal by-products: harmonization of DNA extraction methods from novel ingredients.

Introduction: The increasing global pressure to explore alternative protein sources derived from animal by-products has opened-up opportunities, but it has also created the need to assess their compliance with labelling statements, to ensure consumer's trust in the composition of both feed and food products. Assessing the authenticity of highly processed animal by-products, particularly within the rapidly expanding Halal food market, presents a significant challenge due to the lack of robust and standardized methodologies. However, the success of DNA based authenticity system is highly dependent on the extracted DNA quantity, quality, and purity ratios from heterogeneous matrices. Material and methods: In this work, nine DNA extraction methods were tested on selected processed animal by-products with high-value and interest for the feed industry: meals from poultry meat, blood and feather, and hydrolysates from swine meat and bone, fish, and black soldier fly. The proposed DNA extraction methods are developed to specifically target swine-specific mitochondrial region, as a case study. Results and discussion: Both the conventional CTAB method and the commercial kits, specifically Invisorb® Spin Tissue Mini and NucleoSpin™ Food, demonstrated superior extraction efficiency and quality ratios. Nevertheless, commercial kits enabled faster detection in comparison to the conventional methods. The absence of swine DNA was successfully validated and confirmed in all animal meals and hydrolysates that did not contain swine in their composition beforehand, demonstrating their compliance with the Halal market requirements.

A whole-body transcriptome assembly of the annelid worm Hediste diversicolor.

The Annelida phylum is composed of a myriad of species exhibiting key phenotypic adaptations. They occupy key ecological niches in a variety of marine, freshwater and terrestrial ecosystems. Importantly, the increment of omic resources is rapidly modifying the taxonomic landscape and knowledge of species belonging to this phylum. Here, we comprehensively characterised and annotated a transcriptome of the common ragworm, Hediste diversicolor (OF Müller). This species belongs to the family Nereididae and inhabits estuarine and lagoon areas on the Atlantic coasts of Europe and North America. Ecologically, H. diversicolor plays an important role in benthic food webs. Given its commercial value, H. diversicolor is a promising candidate for aquaculture development and production in farming facilities, under a circular economy framework. We used Illumina next-generation sequencing technology, to produce a total of 105 million (M) paired-end (PE) raw reads and generate the first whole-body transcriptome assembly of H. diversicolor species. This high-quality transcriptome contains 69,335 transcripts with an N50 transcript length of 2313 bp and achieved a BUSCO gene completeness of 97.7% and 96% in Eukaryota and Metazoa lineage-specific profile libraries. Our findings offer a valuable resource for multiple biological applications using this species.

Polychaete (Alitta virens) meal inclusion as a dietary strategy for modulating gut microbiota of European seabass (Dicentrarchus labrax).

Recent research has revealed the significant impact of novel feed ingredients on fish gut microbiota, affecting both the immune status and digestive performance. As a result, analyzing the microbiota modulatory capabilities may be a useful method for assessing the potential functionality of novel ingredients. Therefore, this study aimed to evaluate the effects of dietary polychaete meal (PM) from Alitta virens on the autochthonous and allochthonous gut microbiota of European seabass (Dicentrarchus labrax). Two diets were compared: a control diet with 25% fishmeal (FM) and a diet replacing 40% of fishmeal with PM, in a 13-week feeding trial with juvenile fish (initial weight of 14.5 ± 1.0 g). The feed, digesta, and mucosa-associated microbial communities in fish intestines were analyzed using high-throughput sequencing of the 16S rRNA gene on the Illumina MiSeq platform. The results of feed microbiota analyses showed that the PM10 feed exhibited a higher microbial diversity than the FM diet. However, these feed-associated microbiota differences were not mirrored in the composition of digesta and mucosal communities. Regardless of the diet, the digesta samples consistently exhibited higher species richness and diversity than the mucosa samples. Overall, digesta samples were characterized by a higher abundance of Firmicutes in PM-fed fish. In contrast, at the gut mucosa level, the relative abundances of Mycobacterium, Taeseokella and Clostridium genera were lower in the group fed the PM10 diet. Significant differences in metabolic pathways were also observed between the FM and PM10 groups in both mucosa and digesta samples. In particular, the mucosal pathways of caffeine metabolism, phenylalanine metabolism, and sulfur relay system were significantly altered by PM inclusion. The same trend was observed in the digesta valine, leucine, and isoleucine degradation and secretion pathways. These findings highlight the potential of PM as an alternative functional ingredient in aquafeeds with microbiota modulatory properties that should be further explored in the future.

An in-depth characterisation of European seabass intestinal segments for assessing the impact of an algae-based functional diet on intestinal health.

Sustainable farming of fish species depends on emerging new feed ingredients, which can alter the features of the digestive tract and influence animals' overall health. Recent research has shown that functional feeds hold great potential for enhancing fish robustness by evoking appropriate responses at the intestine level. However, there is a lack of extensive and accurate descriptions of the morphology of the gastrointestinal tract of most farmed fish. We have characterised the intestine of European seabass thoroughly, by targeting four segments - anterior, mid, posterior and rectum. Results indicated that the anterior segment is mostly associated with absorption-related features; this segment has the largest absorptive area, the longest villi, and the highest number of neutral goblet cells (GC). The posterior segment and rectum have distinct histomorphometric features, but both seem to be important for immunity, displaying the highest count of acid GC and the highest expression of immune-related genes. The strongest proliferating cell nuclear antigen (PCNA) signal was observed in the anterior intestine and rectum, with PCNA+ cells appearing at the base of the villi and the corresponding villi branches. We have also evaluated the impact of a novel feed supplemented with a macro- and microalgae blend and found that there were no differences in terms of growth. However, the alterations observed in the mid intestine of fish fed the blend, such as thickening of the submucosa and lamina propria, an increased number of leucocytes, and higher expression of immune- and oxidative stress-related genes, suggest that algae may have an immunomodulatory effect. In the current article, we have described the morphology and expression patterns of the intestine segments of European seabass in detail and have presented a comprehensive report of the indices and methods used for the semi-quantitative and quantitative histomorphometric assessments, thereby providing useful information for future studies that aim to maintain intestinal health through dietary interventions.

Microplastics in water, feed and tissues of European seabass reared in a recirculation aquaculture system (RAS).

Plastic particles (PLs) are ubiquitous in aquatic ecosystems, and aquaculture production is susceptible to contamination from external or endogenous sources. This study investigated PL presence in water, fish feed and body sites of 55 European seabass produced in a recirculating aquaculture system (RAS). Fish morphometric parameters and health status biomarkers were determined. A total of 372 PLs were recovered from water (37.2 PL/L), 118 PLs from feed (3.9 PL/g), and 422 from seabass (0.7 PL/g fish; all body sites analysed). All 55 specimens had PLs in at least two of the four body sites analysed. Concentrations were higher in the gastrointestinal tract (GIT; 1.0 PL/g) and gills (0.8 PL/g) than in the liver (0.8 PL/g) and muscle (0.4 PL/g). PL concentration in GIT was significantly higher than in muscle. Black, blue, and transparent fibres made of man-made cellulose/rayon and polyethylene terephthalate were the most common PLs in water and seabass, while black fragments of phenoxy resin were the most common in feed. The levels of polymers linked to RAS components (polyethylene, polypropylene, and polyvinyl chloride) were low, suggesting a limited contribution to the overall PL levels found in water and/or fish. The mean PL size recovered from GIT (930 µm) and gills (1047 µm) was significantly larger than those found in the liver (647 µm) and dorsal muscle (425 µm). Considering all body sites, PLs bioconcentrated in seabass (BCFFish >1), but their bioaccumulation did not occur (BAFFish <1). No significant differences were observed in oxidative stress biomarkers between fish with low (<7) and high (≥7) PL numbers. These findings suggest that fish produced in RAS are mainly exposed to MPs through water and feed. Further monitoring under commercial conditions and risk assessment are warranted to identify potential threats to fish and human health and define mitigating measures.

A commercial blend of macroalgae and microalgae promotes digestibility, growth performance, and muscle nutritional value of European seabass (Dicentrarchus labrax L.) juveniles.

Algae can leverage aquaculture sustainability and improve the nutritional and functional value of fish for human consumption, but may pose challenges to carnivorous fish. This study aimed to evaluate the potential of a commercial blend of macroalgae (Ulva sp. and Gracilaria gracilis) and microalgae (Chlorella vulgaris and Nannochloropsis oceanica) in a plant-based diet up to 6% (dry matter basis) on digestibility, gut integrity, nutrient utilization, growth performance, and muscle nutritional value of European seabass juveniles. Fish (11.3 ± 2.70 g) were fed with isoproteic, isolipidic, and isoenergetic diets: (i) a commercial-type plant-based diet with moderate fishmeal (125 g kg-1 DM basis) and without algae blend (control diet; Algae0), (ii) the control diet with 2% algae blend (Algae2), (iii) the control diet with 4% algae blend (Algae4), and (iv) the control diet with 6% algae blend (Algae6) for 12 weeks. The digestibility of experimental diets was assessed in a parallel study after 20 days. Results showed that most nutrients and energy apparent digestibility coefficients were promoted by algae blend supplementation, with a concomitant increase in lipid and energy retention efficiencies. Growth performance was significantly promoted by the algae blend, the final body weight of fish fed Algae6 being 70% higher than that of fish fed Algae0 after 12 weeks, reflecting up to 20% higher feed intake of algae-fed fish and the enhanced anterior intestinal absorption area (up to 45%). Whole-body and muscle lipid contents were increased with dietary algae supplementation levels by up to 1.79 and 1.74 folds in Algae 6 compared to Algae0, respectively. Even though the proportion of polyunsaturated fatty acids was reduced, the content of EPA and DHA in the muscle of algae-fed fish increased by nearly 43% compared to Algae0. The skin and filet color of juvenile European seabass were significantly affected by the dietary inclusion of the algae blend, but changes were small in the case of muscle, meeting the preference of consumers. Overall results highlight the beneficial effects of the commercial algae blend (Algaessence®) supplementation in plant-based diets for European seabass juveniles, but feeding trials up to commercial-size fish are needed to fully assess its potential.

Can marine heatwaves affect the fatty acid composition and energy budget of the tropical fish Zebrasoma scopas?

Marine heatwaves (MHWs) are extreme weather events featuring abnormally high seawater temperature, and expected to increase in frequency, duration and severity over this century. The impacts of these phenomena on physiological performance of coral reef species require understanding. This study aimed to evaluate the effects of a simulated MHW (category IV; ΔT = +2 °C, 11 days) (after exposure and 10-day recovery period) on fatty acid (FA) composition (as a biochemical indicator) and energy budget (i.e., growth, G, excretion (faecal, F and nitrogenous losses, U), respiration, R and food consumption, C) of a juvenile tropical surgeonfish species (Zebrasoma scopas). Significant and different changes were found under MHW scenario for some of the most abundant FA and respective groups (i.e., an increase in the contents of 14:0, 18:1n-9, ΣMonounsaturated (ΣMUFA) and 18:2n-6; and a decrease in the levels of 16:0, ΣSaturated (ΣSFA), 18:1n-7, 22:5n-3 and ΣPolyunsaturated (ΣPUFA)). The contents of 16:0 and ΣSFA were also significantly lower after MHW exposure compared to control (CTRL). Additionally, lower feed efficiency (FE), relative growth rate (RGR) and specific growth rate in terms of wet weight (SGRw), as well as higher energy loss for respiration were observed under MHW exposure conditions in comparison with CTRL and MHW recovery period. The energy proportion channelled for faeces dominated the mode of energy allocation, followed by growth in both treatments (after exposure). After MHW recovery, this trend was reversed, and a higher percentage was spent for growth and a lower fraction for faeces than in the MHW exposure period. Overall, FA composition, growth rates and energy loss for respiration of Z. Scopas were the physiological parameters most influenced (mainly in a negative way) by an 11-day MHW event. The observed effects in this tropical species can be exacerbated with increasing intensity and frequency of these extreme events.

Total fishmeal replacement by defatted Tenebrio molitor larvae meal induces alterations in intermediary metabolism of European sea bass (Dicentrarchus labrax).

The replacement of fishmeal (FM) by insect meal (IM) in aquafeed formulation has been thoroughly studied lately, but little is known about their impact on nutrient metabolism of fish. This study evaluated the impact not only of partial but also total FM replacement by IM on intermediary metabolism of European sea bass (Dicentrarchus labrax). A fishmeal-based diet was used as a control (CTRL) and two other diets were formulated to include 20% and 40% of defatted Tenebrio molitor larvae meal (dTM), replacing 50% (TM50) and 100% (TM100) of fishmeal (FM), respectively. After a 16-week feeding trial, a multidisciplinary approach including assessment of histological, biochemical, molecular, and enzymatic parameters was adopted to investigate hepatic and plasmatic responses to the different dietary formulations. The results obtained demonstrated that dTM can be successfully used to replace 50% of FM in diets for European sea bass, without adversely affecting liver health or intermediary metabolism of nutrients. As for TM100, although no signs of steatosis were observed in the liver, the activity of glycolytic and lipogenic genes and enzymes increased when compared to CTRL diet (P < 0.05), resulting in higher levels of plasmatic non-esterified fatty acids and triacylglycerides (P < 0.05), which in the long-term may compromise fish health, thus precluding such a high degree of substitution for use in practical diets for European sea bass.

Insect meal has been increasingly considered as novel protein source in diets for different animal models, including fish. European sea bass is one of the most important fish species in Europe, particularly in the Mediterranean. Fishmeal is considered a premium protein source in diets for aquaculture fish. Thus, this study evaluated the impact of partial and total fishmeal replacement by an insect meal (defatted Tenebrio molitor larvae meal) on intermediary metabolism of European sea bass. After 16 weeks of feeding, the results obtained demonstrated that selected insect meal can be successfully used to replace 50% of fish in diets for European sea bass, without adversely affecting liver health or intermediary metabolism of nutrients. On the other hand, total fishmeal replacement by insect meal may compromise fish health in the long-term.

Nucleotides and free amino acids in sea urchin Paracentrotus lividus gonads: Contributions for freshness and overall taste.

This study aims to report the chemical changes, specifically the nucleotides and free amino acids (FAAs) during refrigerated storage of live sea urchin Paracentrotus lividus (7 °C) and packed gonads (2 °C) and respective contributions to overall taste. Results showed that the adenylate energy charge (AEC) is an adequate indicator for live sea urchin through storage, while K-value does not distinguish freshness. Changes of both indexes were not clear in packed gonads. The FAAs profile were related with maturation stage where amino acids associated to sweet (Gly, Ala), umami (Glu) and bitter (Arg, Lys, His, Val) had significant contribution to overall taste. In general, the storage did not significantly affect the FAAs content nor its contribution to overall taste in contrast to nucleotides that seemed to induce potential changes after day 5. The findings provide insights that will complement a full study on quality index scheme development of the products.

Lack of detrimental effects of ocean acidification and warming on proximate composition, fitness and energy budget of juvenile Senegalese sole (Solea senegalensis).

Rising levels of atmospheric carbon dioxide (CO2) are driving ocean warming and acidification, which may negatively affect the nutritional quality and physiological performance of commercially important fish species. Thus, this study aimed to evaluate the effects of ocean acidification (OA; ΔpH = -0.3 units equivalent to ΔpCO2 ~ +600 µatm) and warming (OW; ΔT = +4 °C) (and combined, OAW) on the proximate composition, fitness and energy budget of juvenile Senegalese sole (Solea senegalensis). After an exposure period of 75 days, growth (G), metabolism (R) and excretion (faecal, F and nitrogenous losses, U) were assessed to calculate the energy intake (C). Biometric and viscera weight data were also registered to determine animal fitness. Overall, the proximate composition and gross energy were not significantly affected by acidification and warming (alone or in combination). Weight gain, maximum and standard metabolic rates (MMR and SMR, respectively), aerobic scope (AS) and C were significantly higher in fish subjected to OA, OW and OAW than in CTR conditions. Furthermore, the highest relative growth rates (RGR), specific growth rates in terms of wet weight (SGRw) and protein (SGRp), as well as feed efficiencies (FE) occurred in fish submitted to OW and OAW. On the other hand, fish exposed to CTR conditions had significantly higher feed conversion ratio (FCR) and ammonia excretion rate (AER) than those exposed to simulated stressors. Regarding energy distribution, the highest fraction was generally allocated to growth (48-63 %), followed by excretion through faeces (36-51 %), respiration (approximately 1 %) and ammonia excretion (0.1-0.2 %) in all treatments. Therefore, ocean warming and acidification can trigger physiological responses in juvenile Senegalese sole, particularly in their energy budget, which can affect the energy flow and allocation of its population. However, and in general, this species seems highly resilient to these predicted ocean climate change stressors.

Rearing Environment during the Endogenous Feeding Stage of Acipenser baerii.

The aim of this study was to evaluate behaviour, growth, lipid composition, muscle development, and stress status of Siberian sturgeon larvae reared with two types of substrate: Bioballs1 (BB1) and Bioballs2 (BB2), when compared to no substrate (CTR). Sampling points were: hatching (T0), schooling (T1), and yolk-sac full absorption (T2). BB1 larvae were less active and showed no schooling behaviour. At T1 and at T2, BB1 larvae showed a significantly higher weight and total length than larvae reared in either CTR or BB2 (p < 0.05). The lipid content of larvae decreased over time, with little relevant differences between groups. At T2, total muscle area, slow muscle area and fast muscle area were significantly higher in larvae reared in BB1 (p < 0.05). No significant differences in muscle proliferation were found between groups. Real Time PCR was used for evaluating the relative expression of a pool of genes: myod, myog, mrf4, igf2, hsp70, hsp90a, hsp90b, and glut2. The expression of these genes did not seem to be much affected by the type of rearing substrate, except for myog and hsp70 at T1, which was greater in BB2 larvae. Our data suggest that the presence of a substrate during this developmental period seems to have positive effects but further studies would be necessary during the exogenous feeding stage.

Comparative Analysis between Synthetic Vitamin E and Natural Antioxidant Sources from Tomato, Carrot and Coriander in Diets for Market-Sized Dicentrarchus labrax.

Synthetic vitamin E is commonly used in aquafeeds to prevent oxidative stress in fish and delay feed and flesh oxidation during storage, but consumers' preferences tend towards natural antioxidant sources. The potential of vegetable antioxidants-rich coproducts, dried tomato (TO), carrot (CA) and coriander (CO) was compared to that of synthetic vitamin E included in diets at either a regular (CTRL; 100 mg kg-1) or reinforced dose (VITE; 500 mg kg-1). Natural antioxidants were added at 2% to the CTRL. Mixes were then extruded and dried, generating five experimental diets that were fed to European sea bass juveniles (114 g) over 12 weeks. Vitamin E and carotenoid content of extruded diets showed signs of degradation. The experimental diets had very limited effects on fish growth or body composition, immunomodulatory response, muscle and liver antioxidant potential, organoleptic properties or consumer acceptance. Altogether, experimental findings suggest that neither a heightened inclusion dose of 500 mg kg-1 of vitamin E, nor a 2% inclusion of natural antioxidants provided additional antioxidant protection, compared to fish fed diets including the regular dose of 100 mg kg-1 of vitamin E.

Development of a Rate-All-That-Apply (RATA) ballot for sensory profiling of sea urchin (Paracentrotus lividus) gonads.

Paracentrotus lividus gonads are receiving increasing interest for their unique sensory attributes. However, the sensory profile of this highly demanded gourmet product has not yet been well described, and doing so may potentially benefit the gonads' marketability and acceptability. The main goal of this study was to build a sensory profile of sea urchin (Paracentrotus lividus) gonads, to evaluate differences between sex and harvest location. Eighty untrained panellists (regular consumers of seafood) were asked to evaluate four samples of raw sea urchin gonads (inside a sea urchin test), divided by sex and harvest location. The panellists evaluated overall liking and acceptance (Food Action Scale), followed by a Rate-All-That-Apply (RATA) ballot with a list of 22 sensory attributes divided into four dimensions: appearance (6), odour (6), texture (4) and taste (6). No significant effects of sex and harvest location were identified for liking, but a significant effect of the sex for the Food Action Rating Scale (FACT) was identified. Sensory profiling clearly separated gonads according to sex, with females being more appealing than males. Females were strongly correlated with a pleasant and intense tropical taste, as well as an overall appealing and grainy appearance and a pleasant tropical odour, while males had a slimy appearance and a milky white exudate. When compared with the Check-All-That-Apply (CATA) approach used in our previous study, the use of the RATA approach allowed to discriminate female gonads according to their origin, with those from Praia Norte being firmer, more resilient and more appealing than the ones from Carreço. This study reinforced the fact that female sea urchins tend to present an intense and pleasant tropical taste and a pleasant tropical odour, thus being more appealing to the panellists, contributing valuable information for future nutritional aquaculture studies aiming to enhance sea urchin gonads' attributes and, subsequently, their market valorisation.

Dietary Curcumin Promotes Gilthead Seabream Larvae Digestive Capacity and Modulates Oxidative Status.

The larval stage is highly prone to stress due to the ontogenetic and metabolic alterations occurring in fish. Curcumin inclusion in diets has been shown to improve growth by modulating oxidative status, immune response, and/or feed digestibility in several fish species. The aim of the present work was to assess if dietary curcumin could promote marine fish larvae digestive maturation and improve robustness. Gilthead seabream larvae were fed a diet supplemented with curcumin at dose of 0 (CTRL), 1.5 (LOW), or 3.0 g/Kg feed for 27 days. From 4 to 24 days after hatching (DAH), no differences were observed in growth performance. At the end of the experiment (31 DAH) LOW larvae had a better condition factor than CTRL fish. Moreover, HIGH larvae showed higher trypsin and chymotrypsin activity when compared to CTRL fish. LOW and HIGH larvae were able to maintain the mitochondrial reactive oxygen species production during development, in contrast to CTRL larvae. In conclusion, curcumin supplementation seems to promote larvae digestive capacity and modulate the oxidative status during ontogeny. Furthermore, the present results provide new insights on the impacts of dietary antioxidants on marine larvae development and a possible improvement of robustness in the short and long term.

Dietary Natural Plant Extracts Can Promote Growth and Modulate Oxidative Status of Senegalese Sole Postlarvae under Standard/Challenge Conditions.

Plant extracts are known for their high content and diversity of polyphenols, which can improve fish oxidative status. A growth trial with Senegalese sole postlarvae (45 days after hatching) fed with one of four experimental diets-control (CTRL), and supplemented with curcumin (CC), green tea (GT), and grape seed (GS) extracts-was performed to assess if supplementation could improve growth performance and oxidative status. At the end of the growth trial, postlarvae were submitted to a thermal stress to assess their robustness. Sole growth was improved by CC and GS diets when compared to those fed the CTRL. CC and CTRL postlarvae presented the lowest oxidative damage (lipid peroxidation and protein carbonylation values). Stress-related biomarkers (heat shock protein 70 and glutathione-S-transferase) decreased in CC fish compared to those fed the CTRL diet, which might be due to a direct antioxidant capacity. In contrast, oxidative damage increased in GT and GS sole reared in standard conditions. However, after a thermal stress, GT and GS diets prevented the increase of protein carbonylation content and the decrease of antioxidant glutathione, depending on exposure time. Overall, dietary supplementation with natural extracts modulated oxidative status and stress response after a short/long-term exposure to temperature.

The Use of Defatted Tenebrio molitor Larvae Meal as a Main Protein Source Is Supported in European Sea Bass (Dicentrarchus labrax) by Data on Growth Performance, Lipid Metabolism, and Flesh Quality.

OBJECTIVE: This study aims to determine the maximal inclusion level of defatted (d-) Tenebrio molitor larvae meal (TM) able to replace dietary fishmeal (FM) without compromising growth performance, general metabolism, and flesh quality traits in European sea bass, and to evaluate the major underlying physiological mechanisms. MATERIALS AND METHODS: Fish (55 ± 2 g) were fed with diets containing increasing levels of dTM: 0, 40, 80 and 100% (CTRL, TM40, TM80, and TM100, respectively) to replace FM. After 10 weeks of feeding, the growth performance, nutrient and energy balance, intestinal integrity, plasma metabolites and the expression of genes related to growth and nutrient metabolism, in liver and muscle were determined. The fatty acids (FA) profile, textural properties and color were also evaluated in muscle. RESULTS: Protein and lipids digestibility remained unaltered up to 80% dTM inclusion. Growth performance parameters were similar among dietary treatments. The dTM inclusion increased the hepatosomatic index in fish fed TM100. Muscle eicosapentaenoic acid, docosahexaenoic acid and n-3 long-chain polyunsaturated FA levels were maintained up to 80% dTM inclusion, but total cholesterol and non-esterified FA increased with dietary dTM inclusion. In liver, the expression of elongation of very long-chain FA protein 6 (elovl6) and FA desaturase 2 (fads2) did not change in fish fed TM40 and TM80, but elovl6 decreased whilst fads2 increased in fish fed TM100 when compared to those fed CTRL. The expression of cholesterol 7 alpha-monooxygenase (cyp7a1) decreased with dietary dTM inclusion. In muscle, the expression of myoblast determination protein-2 (myod2) decreased in fish fed TM80 and TM100. CONCLUSION: It is feasible to substitute dietary FM by dTM up to 80% in European sea bass without detrimental effects on nutrient digestibility, growth performance and associated genetic pathways, whilst assuring fillet nutritional value for human consumption.

Processed by-Products from Soy Beverage (Okara) as Sustainable Ingredients for Nile Tilapia (O. Niloticus) Juveniles: Effects on Nutrient Utilization and Muscle Quality.

The apparent digestibility coefficients (ADCs) of differently processed okara meals were assessed in Nile tilapia diets: dried okara not autoclaved (FOK), dried okara autoclaved (AOK), okara hydrolyzed with Alcalase (ALOK) or Cynara cardunculus proteases (CYOK), and hydrolyzed okara fermented with lactic bacteria: Lactobacillus rhamnosus R11 (CYR11OK) or Bifidobacterium animalis ssp. lactis Bb12 (CYB12OK). Okara processing significantly affected nutrient digestibility: dry matter ADC was highest in CYR11OK (80%) and lowest in FOK (40%). The lowest protein digestibility was observed in CYR11OK (72%), and the highest in AOK (97%) and CYOK (91%), evidencing the effectiveness of the autoclave and the use of C. Cardunculus proteases to increase okara protein bioavailability. The inclusion of up to 20% of AOK or CYOK did not affect fish growth, nutrient utilization, or whole body composition of Nile tilapia. The flesh quality (color, pH, water activity, cohesiveness, elasticity and resilience) was not affected by the dietary incorporation of AOK or CYOK. Fish fed with AOK diets stand out for their high density of muscle fibers, particularly in AOK20, which can explain their high muscle firmness and may result in further hypertrophic growth. Altogether, results suggest that hydrolyzed or autoclaved okara are valuable ingredients for Nile tilapia diets.

Sensory profiling, liking and acceptance of sea urchin gonads from the North Atlantic coast of Portugal, aiming future aquaculture applications.

Sea urchin gonads are receiving increasing attention for their exclusive sensorial attributes. However, the sensory profile of this highly demanded gourmet product has not yet been well described, and it may potentially help enhancing the gonads' marketability and acceptability. The main goal of this study was to build a sensory profile of sea urchin (Paracentrotus lividus) gonads, to evaluate differences between sex, harvest location, as well as the impact of presentation on consumer acceptance. Sixty untrained panellists (regular consumers of seafood) were asked to evaluate eight samples of raw sea urchin gonads, divided by sex, harvest location and presentation (in a clear translucent glass bowl or inside a sea urchin test). The panellists evaluated overall liking and acceptance (Food Action Scale), followed by a Check-All-That-Apply (CATA) ballot with a list of 38 sensory attributes divided into four dimensions: appearance (9), odour (8), texture (7) and taste (14), launched in Sense Gest. From a three-way ANOVA, no significant effect of sex, harvest location and presentation were identified for both liking and acceptance. However, a significant interaction between presentation and sex was identified: females with gourmet presentation were rated higher than females presented in a bowl; and males presented in a bowl were favoured in relation to gourmet presentation. Sensory profiling clearly separates gonads according to sex, with females being more appealing than males that presented a milky white fluid. Gonads were also separated according to the presentation method: the white background of the bowl seemed to highlight the orange colour of females; the gourmet presentation favoured the females in relation to the males, mainly because the male gonad colour and white-colour exudate were emphasized by the background of the sea urchin test. Moreover, the gourmet presentation in both sexes was correlated with a fresh, tropical and pleasant odour. This study concluded that sea urchin with an orange gonad and a sweet, fresh and tropical flavour is preferable, which will allow future nutritional research efforts to be focused on the enhancement of these gonad attributes.