Hake Fillets Research Articles

Schiff base crosslinked gelatin-Spirulina platensis protein concentrate films with enhanced antioxidant activity.

The aim of this work is to produce bioactive films suitable for aerobic packaging applications by combining the bioactivity of Spirulina platensisprotein concentrate (PC; 1% and 2% w/w), the sustainable nature of bovine gelatin (Ge), and sodium alginate dialdehyde (ADA, 5% w/w) as Schiff base crosslinking agent.PC was obtained by an optimized acid-base extraction process and characterized. PC showed a dose-dependent radical scavenging activity (RSA; IC50 =24.3mg/L) related to its high content of C-phycocyanin and total phenolic compounds (32.44±1.37mg gallic acid equivalents per gram of PC). As a general trend, crosslinking decreased the water solubility, improved mechanical properties, and helped improve RSA of Ge-ADA-PC films. Ge-5ADA-2PC film recorded best compromise between solubility (only 33.6%), high UV barrier (0.134% transmittance at 400nm), reasonable extensibility (217.00±2.34%), tensile strength (3.50±0.43MPa), water vapor permeability (2.00±0.17×10-12 kg·m/m2 ·Pa·s), and RSA (44.70±2.19%). Wrapping hake fillets in this filmdelayed lipid oxidation during storage under refrigerated conditions for 11days, maintaining the thiobarbituric acid indexbelow 0.5mg malonaldehyde/kg muscle. Results suggest that Ge-ADA-PC films have potential as aerobic packaging materials for oxidation-sensitive food. PRACTICAL APPLICATION: The combination of gelatin, alginate dialdehyde and Spirulina platensis protein concentrate gave rise to fully biobased films with reduced water solubility and enhanced antioxidant activity, which were able to delay the secondary lipid oxidation of refrigerated seafood. This study also shows the potential of cyanobacteria as renewable resources of high-value ingredients for the design of active and intelligent aerobic packaging solutions.

Comprehensive analysis of vacuum application in desalting lean white fish to develop a highly acceptable ready-to-use product

Changes in consumers' lifestyle, coupled with a trend towards healthier low-sodium food, have led to a decline in salted fish consumption. Today, ready-to-use, high-quality food products are what the consumer demands. We evaluated the use of vacuum during the desalting of heavily salted hake, to develop a ready-to-use product. A partial vacuum pressure of 10,000 Pa was applied for 15 min (DV), and for 5 min followed by 5 min at atmospheric pressure in three pulses (DVP). Both were compared with the treatment at atmospheric pressure (DC). The application of vacuum during desalting hake fillets had significant effects on product yield and salt transfer kinetics. DV was more effective when considering the product yield, while DVP samples reached the lowest NaCl values. Vacuum pulses reduced the desalting time by at least 66%, resulting in lower aw values that would influence the product's microbiological stability. Vacuum did not modify the product texture significantly, though the effect of DVP was greater compared to DC. The developed desalted product had high sensory acceptability scores when evaluated by the consumer panel. The use of vacuum pulses would be a feasible and economical alternative to reduce desalting processing times of this ready-to-use fish product.

Changes in Volatile Composition of Cape Hake Fillets under Modified Atmosphere Packaging Systems during Cold Storage.

Fresh ready-to-cook fish fillets are susceptible to loss of freshness and accumulation of off-odour due to accelerated microbial spoilage. Suboptimal storage temperature and packaging conditions accelerate this process, limiting the economic potential. This study investigated the effects of modified atmosphere packaging (MAP) and storage temperature (0 °C and 4 °C) on the volatile compounds (VOCs) of Cape hake (Merluccius capensis) fish fillets as a predictor of shelf life and quality. Fresh Cape hake fillets were packaged under active modified atmosphere (40% CO2 + 30% O2 + 30% N2) and passive modified atmosphere (0.039% CO2 + 20.95% O2 + 78% N2) with or without an absorbent pad and stored at 0 °C and 4 °C for 12 d. The results obtained demonstrated that changes in VOCs and concentration were significantly (p < 0.05) influenced by MAP conditions, storage temperature and duration. A total of 16 volatiles were identified in the packaged Cape hake fillets: 4 primary VOCs and 12 secondary VOCs. The spoilage VOCs identified include tri-methylamine (TMA) (ammonia-like), esters (sickeningly sweet) and sulphur group (putrid). The concentration of secondary VOCs increased continuously during storage. Active-MA-packaged fillets performed better and had lower TMA values of 0.31% at 0 °C on day 12 in comparison to 7.22% at 0 °C under passive on day 6. Ethyl acetate was detected in passive-MA-packaged fillets stored at 0 °C on day 3, and the levels increased to 3.26% on day 6, while active-MA-packaged fillets maintained freshness. This study showed that in conjunction with TMA, VOCs such as esters and sulphur-related compounds could be used as spoilage markers for Cape hake fish fillets.

Essential oil in vapor phase in combination with Enterococcus mundtii STw38 to improve refrigerated hake fillets shelf-life

Essential oils (EOs) in vapor phase were applied together with the bacteriocinogenic strain E. mundtii STw38 to improve the shelf life of Argentinean hake -Merluccius hubbsi-. Evaluated EOs were oregano, thyme, rosemary, and lemongrass. In vitro results demonstrated their effectiveness against foodborne pathogen surrogate Listeria innocua, as well as against Lactobacillus plantarum, Shewanella putrefaciens, and fish indigenous biota. The most effective were oregano and lemongrass, showing the lowest minimal inhibitory concentration, and synergic activity when combined against L. innocua and S. putrefaciens. Furthermore, synergic mixtures promoted changes in target microorganisms cell wall. The composition of the volatile phase of a synergic EOs mixture showed a higher presence of oregano components. When applying the EOs alone in hake fillets, total bacteria count increased 3.3 log cycles whereas in the control system the increase was higher than 5 log cycles, and consumers evaluated similarly in taste and smell both the control and the EOs synergic mixtures. When adding the most concentrated synergic mixture (0.147 μL lemongrass/mL headspace and 0.195 μL oregano/mL headspace) together with the bioprotective culture, in 7 days total bacteria count only increased 3 log cycles, showing the effectiveness of the use of EOs together with E. mundtii STw38.

Effects of Modified Atmosphere Packaging, Storage Temperature, and Absorbent Pads on the Quality of Fresh Cape Hake Fish Fillets

This study investigated the effects of modified atmosphere packaging (MAP), storage temperature, and the use of absorbent pads (PAD) on the quality attributes of Cape hake (Merluccius capensis) fish fillets. Fresh Cape hake fillets were packaged under active-MA (40% CO2 + 30% O2 + 30% N2) or passive-MA (0.039% CO2 + 20.95% O2 + 78% N2), with and without PAD, and stored at 0 °C, 4 °C, and 8 °C (to mimic abuse temperature). The control fresh fillets were stored under passive-MAP without PAD at 0 °C, 4 °C, and 8 °C. Headspace O2 gas composition continuously decreased below critical limits under passive-MAP, with an increase in storage temperature. Similarly, O2 levels decreased under active-MAP but did not reach critical levels, with the lowest being 9.5% at 0 °C. The interaction of storage temperature and modified atmosphere had a significant effect on quality attributes of Cape hake fillets. Drip loss was higher in active-MAP packaged fillets without PAD (0.64%) than passive-MAP packaged fillets without PAD (0.27%). Drip loss was significantly reduced when using absorbent pads (p &lt; 0.05). Firmness, color, and pH were better maintained under active-MAP at the lowest temperature of 0 °C. Firmness (work of shear) of active-MA packaged fillets on day 12 at 0 °C and 4 °C was 527 N/s and 506 N/s, respectively. Fillets packaged under active-MAP at 0 °C had longer shelf-life than control passive-MAP fillets.

Mercury levels in Merluccius merluccius muscle tissue in the central Mediterranean Sea: Seasonal variation and human health risk

In this study we analysed total mercury (THg) levels in European hake (Merluccius merluccius) – an ecologically and commercially important species throughout the Mediterranean – caught in the northern and central Adriatic Sea. To the best of our knowledge, this is the first study evaluating THg levels in hake fillets in relation to ecological (season) and biological (body size, sex, sexual maturity, lipid content) parameters. THg levels in muscle showed no sex-related differences; in contrast, significant season-related differences were found in females, with higher levels in spring-summer compared with autumn-winter. No season-related differences were seen in males. A significant sex effect was found for body size and sexual maturity. Females showed a correlation between THg level and length, THg being significantly higher in mature compared with immature specimens. No significant sex effect was found for muscle lipid content, because a correlation between THg concentration and tissue lipids was found in both sexes.Since the mean THg concentration found in M. merluccius fillets (0.64 ± 0.29 mg kg−1 dry weight; range, 0.20–1.53) was consistently under the level set by EU regulations, this study demonstrates that European hake caught in the northern and central Adriatic is safe for human consumption.

Structure of fish proteins as modified by salting procedures: A rheological and ultrastructural analysis of hake (Merluccius hubbsi) fillets.

Salting is a technique used for preserving fish meat and allows obtaining added value products. The salting process provokes several structure modifications, which in turns cause changes in the fish texture. Thus, the objective of this study was to investigate the effect of three salting procedures (dry salting [DS], mixed salting [MS] and brining [BS]) on the rheology and structure of Merluccius hubbsi (Argentine hake). Rheological properties were evaluated using dynamic oscillatory and thermorheology tests, and the structure changes by scanning electron microscopy. DS samples showed the highest values of salt concentration referred to liquid phase (zNaCl ), while BS showed the lowest ones. In all cases, elastic (G') and loss (G″) modulus increased with salting time. G' values exceeded G″ values, indicating a predominant solid behavior. DS samples presented the greatest increase in rheological parameters (G', G″ and η*). Thermomechanical spectra allowed to identify an increase in denaturation temperature (Td) of proteins (myosin and actin) for DS and MS, and to a lesser extent for BS (Td=46.7± 0.4°C, Td=50.3± 0.8°C, Td=58.8± 0.6°C and Td=58.2± 0.9°C for fresh, BS, MS and DS, respectively). Ultrastructural images evidenced conformational changes on the myofibrillar proteins and the connective tissue (collagen). BS caused the least superficial damage to hake tissue. Based on the results, BS could be the method recommended for the industrial production of salted M. hubbsi. PRACTICAL APPLICATION: During salting of hake, variations in water and salt content have a significant effect on the myofibrillar and connective tissue proteins. The study of rheological properties and microstructure allows a better understanding of the conformational changes induced by the salting process. The least surface damage exhibited by brining fillets is consistent with the mass transfer mechanism that leads to the formation of a film on the muscle surface that dilutes the salt; for this reason, compared to dry and mixed salting, brining could be the method recommended for the industrial production of salted (>15% w/w) Merluccius hubbsi.

Analysis of added phosphates in hake fillets by ion-exchange chromatography: A case study of false positives induced by nucleotides coelution

This study aimed to optimize an ion-exchange chromatography method for an accurate quantification of phosphates. Coelution of nucleotides was detected following the quantification of small amounts of di- and trimetaphosphates in hake fillets. In some samples, triphosphates were added to the glaze ice, therefore, defrosting waters (glaze ice + drip loss of fillets) should be analyzed for an effective assessment of the use of phosphates in seafood. Even low amounts of adenosine 5′-diphosphate (ADP) and inosine 5′-monophosphate (IMP) triggered false positive results for P2O74− and P3O93−. Keeping the initial isocratic conditions for longer was crucial for the separation of ADP from P2O74− and of IMP from P3O93−. The improved method showed that in general, hake fillets did not have diphosphates, and trimetaphosphates were residual. Triphosphates were clearly added in only four defrosting waters, and in most of the remaining ones, diphosphates and trimetaphosphates contents corresponded to false positive results.

Effect of salting procedures on quality of hake (Merluccius hubbsi) fillets

The influence of salting procedures on the proximate analysis, mechanical parameters, and color of hake (Merluccius hubbsi) was investigated. Three procedures were comparatively evaluated: dry salting (DS), mixed salting (MS) and brining (BS). MS samples had the highest fat content, a considerable protein content and an equilibrium salt content similar to BS. MS samples had a great water loss, as DS method, but hardness and other mechanical parameters were similar to that obtained with BS, i.e. significantly lower than DS. All samples showed color parameters significantly different as compared to fresh hake, turning more red-orange as the salting time increased. Lightness diminished, a∗ values increased and b∗ values did not show a clear trend throughout the salting time. Principal component analysis (PCA) described the relationship between some variables (zNaCl, color, and mechanical parameters) with salting time. High Pearson's correlation coefficients were found between zNaCl and hardness, springiness, cohesiveness and a∗ parameter (r = 0.76, p < 0.001; r = 0.93, p < 0.0001; r = 0.95, p < 0.001 and r = 0.93, p < 0.0001, respectively). Luminosity was negatively correlated with zNaCl (r = -0.87, p = 0.0001). The correlation curves showed nonlinear relationships (R2adj between 83.7 % and 97.4 %), which could be used to predict quality attributes of hake fillets as a function of salting time. This work contributed to know the effect of different salting procedures on the quality attributes of a species widely available in the Southwest Atlantic Ocean.

Quality of Frozen Hake Fillets in the Portuguese Retail Market: A Case Study of Inadequate Practices in the European Frozen White Fish Market.

The overall quality of frozen hake fillets in the Portuguese market was evaluated. Physical, biochemical, microbiological, and sensory analysis in 20 brands revealed several non-conformities. Hake was identified in 19 brands, although two mislabeled the species. Lower net weight than labeled was evidenced in ca. one-third of brands. TVB-N in ca. one-third of the samples presented high values, although within legal limit. Almost all brands presented excessive amount of ice glaze, low levels of WHC (raw/cooked), low levels of soluble protein, and undue thaw-drip loss, thus reflecting the poor quality of fillets. Added phosphates were below the legal limit in all samples; however, they were used in glaze ice in three brands, and only labeled in one. Overall microbiological quality of frozen fillets was good, though yeasts and molds detected in six samples indicate poor hygienic conditions in some facilities. Labels comply with legal requisites, however, need improvement, namely the ‘best before’ periods. In general, packaging was efficient regarding presence of ice crystals and dehydration signs. Concerning sensory analysis of cooked fillets, 63% of the brands had bad to poor quality and 37% fair quality. Merluccius productus revealed the worst quality, namely regarding thaw drip loss, thaw drip loss protein, M/P ratio, pH and sensory evaluation. Overall results show that a significant part of the hake fillets business operators are still failing in relation with best practices.

Mathematical modeling of mass transfer kinetics during salting procedures of hake fillets

The aim of the study was to analyze the influence of salting on the mass transfer kinetics of hake (Merluccius hubbsi) fillets. Three salting procedures were studied comparatively: dry salting (DS), mixed salting (MS), and brining (BS). The evolution of the following variables was determined: salt and water content, total mass changes, and water activity (aw). Total mass change was negative in all treatments. BS presented the least weight loss, indicating higher process yield. Dry salted hake was the most dehydrated, presenting the lowest moisture value and the maximum salt content. The mass transfer kinetics curves were successfully described by the Peleg, Zugarramurdi and Lupin, and Weibull models. The Weibull model showed the best performance in all cases. DS showed the shortest salting time according to the Weibull model parameters. This study elucidated the mass transfer kinetics in salted Meluccius hubbsi hake, a widely available species in the Southwest Atlantic Ocean. Practical applications Salting is a preliminary preservation process used for the development of many traditional and innovative fish products. To obtain a better understanding of the industrial process, it is important to model and quantify the kinetics and process yield. Mathematical modeling is an important tool to describe the behavior of mass transfer during salting and to estimate equilibrium concentrations and processing time, which are essential variables from the industrial point of view. On the other hand, Meluccius hubbsi is a species similar to traditional cod and is widely available in the Southwest Atlantic Ocean. Thus, salted hake could be an alternative to increase the added value of fish products and diversify the seafood offer.

A novel method to deliver natural antimicrobial coating materials to extend the shelf-life of European hake (Merluccius merluccius) fillets

• Natural antimicrobial solutions of chitosan (CS), chitosan nanoparticles (CS NP), carnosolic acid nano-solubilisate were coated on hake fillets using an aerosolisation treatment method. • A combination of VSP and aerosolisation extended the shelf life of hake fillets. • Aerosolisation treatments can be used as additional hurdle technology. The objectives of this study were to investigate the effectiveness of aerosolisation as a novel method for coating natural antimicrobials solutions of chitosan (CS), chitosan nanoparticles (CS NP) and commercially available carnosolic acid nano-solubilisate (CASB) with a view to provide an additional hurdle to extend the shelf-life of vacuum skin packaging (VSP) European Hake ( Merluccius merluccius ) fillets. The aerosolisation of hake fillets with natural antimicrobial solutions of 0.1 % w/v CS, 0.1 % w/v CS NP, or 0.8 % w/v CASB extended significantly ( P < 0.05) the shelf-life of VSP hake fillets by up to 40, 50, and 55 %, respectively compared to untreated control samples. Moreover, the pH of hake fillets was significantly (P < 0.05) increased by CS and CS NP treatments compared to untreated control and CASB treatments. The colour parameters of treated hake fillets increased significantly throughout storage, independent of antimicrobial treatment for all samples. However, lightness was significantly ( P < 0.05) reduced by CASB treatments (compared to other treatments), redness was significantly ( P < 0.05) increased by CS NP treatments (compared to other treatments), and yellowness was significantly ( P < 0.05) increased with all CS, CS NP, and CASB treatments (compared to control samples). In addition, the whiteness index (WI) of hake fillets was reduced significantly ( P < 0.05) when aerosolised with CS, CS NP, and CASB treatments. The lipid oxidation (TBARS) of hake fillets, independent of the antimicrobial treatment, decreased significantly ( P < 0.05) throughout storage. The results from this study indicate that aerosolisation of natural antimicrobial materials can effectively extend the shelf-life of fish products.

Vacuum impregnation in Merluccius hubbsi hake fillets brining. Effect on mass transfer kinetics, texture and colour

Brining is a preliminary process for the development of many traditional and innovative fish products. We analysed the use of vacuum impregnation (VI) in hake fillets brining (10 g NaCl/100 mL solution, 4 ± 2 °C). VI brining (p1 = 10000 Pa, t1 = 5 min, restoring atmospheric pressure for 25–415 min) was compared with brining at atmospheric pressure (control). VI had a significant effect on mass transfer kinetics, yielding a higher Total Mass Change (ΔM) and salt content, which implied shorter brining times as well as higher product yield. Brined fillets presented lower L*, a* and b* values compared to fresh samples. VI did not affect colour when comparing with control. Likewise, texture varied with brining time, but not due to VI. Principal Component Analysis indicated that unbrined fresh hake and samples brined for 240 min (either VI or control) were different in their ΔM, NaCl content, colour and elasticity. Peleg equation accurately modeled salt and water contents behavior during brining, predicting a 75% processing time reduction by the use of vacuum impregnation.

Characterization of the Spoilage Microbiota of Hake Fillets Packaged Under a Modified Atmosphere (MAP) Rich in CO2 (50% CO2/50% N2) and Stored at Different Temperatures.

The aim of this study was to characterize the spoilage microbiota of hake fillets stored under modified atmospheres (MAP) (50% CO2/50% N2) at different temperatures using high-throughput 16S rRNA gene sequencing and to compare the results with those obtained using traditional microbiology techniques. The results obtained indicate that, as expected, higher storage temperatures lead to shorter shelf-lives (the time of sensory rejection by panelists). Thus, the shelf-life decreased from six days to two days for Batch A when the storage temperature increased from 1 to 7 °C, and from five to two days—when the same increase in storage temperature was compared—for Batch B. In all cases, the trimethylamine (TMA) levels measured at the time of sensory rejection of hake fillets exceeded the recommended threshold of 5 mg/100 g. Photobacterium and Psychrobacter were the most abundant genera at the time of spoilage in all but one of the samples analyzed: Thus, Photobacterium represented between 19% and 46%, and Psychrobacter between 27% and 38% of the total microbiota. They were followed by Moritella, Carnobacterium, Shewanella, and Vibrio, whose relative order varied depending on the sample/batch analyzed. These results highlight the relevance of Photobacterium as a spoiler of hake stored in atmospheres rich in CO2. Further research will be required to elucidate if other microorganisms, such as Psychrobacter, Moritella, or Carnobacterium, also contribute to spoilage of hake when stored under MAP.

Modelling microbial growth in modified-atmosphere-packed hake (Merluccius merluccius) fillets stored at different temperatures.

Market globalization and changes in purchasing habits pose a challenge to the fishery industry because of the short shelf life of fish products. In view of this scenario, it would be very helpful if tools capable of predicting the shelf-life of fish could be developed. Thus, the objective of this study was to employ a modelling approach capable of predicting the evolution of the microbiota of hake fillets packaged under a modified atmosphere (MAP) rich in CO2 (50% CO2 / 50% N2) when stored at temperatures ranging between 1 and 10 °C. Growth curves of ten microbial groups were obtained at four different temperatures and fitted with the Baranyi model. Photobacterium showed high growth rates in hake fillets (0.99 days-1 at 4 °C), similar to those of Shewanella, lactic acid bacteria, and non-specific microbial groups investigated, and significantly higher than those of Pseudomonas. Furthermore, no lag phase was observed for Photobacterium regardless of the temperature investigated. On the other hand, Enterobacteriaceae and moulds and yeasts displayed low growth fitness, and their counts increased by <1.5-2 Log10 cycles along the incubation period regardless of storage temperature. The influence of storage temperature on growth parameters (λ, μmax and Yend) was subsequently studied, and secondary models were developed for the eight most relevant microbial groups. All of the final equations developed in this study showed R2 values ≥0.90, and RMSE values ≤0.50. In addition, results obtained in this investigation strongly suggest that Photobacterium would be the main responsible microorganism for the spoilage of hake fillets stored under MAP conditions (50% CO2/50% N2) along the entire range of temperatures investigated (1-10 °C).

Evaluation of Smart Portable Device for Food Diagnostics: A Preliminary Study on Cape Hake Fillets (M. capensis and M. paradoxus)

The new smartphone-based food diagnostic technologies offer significant advantages over traditional methods as they can be easily applied in various steps of the agrifood supply chain including household use and also in the food recovery field for charitable purposes, aimed at helping to reduce food waste. Further advantages include the low cost, the minimal equipment, and nonspecialized personnel required. This study evaluated the performance of two instrumental measurements of the sensors: an electronic nose (PEN3; WinMuster Airsense Analytics) and a smart portable device (FOODsniffer; ARS LAB US). The preliminary study was conducted on cape hake fillets. In order to test the performance of PEN3 and FOODsniffer, total volatile basic nitrogen (TVB-N) values were considered as the reference. Principal component analysis (PCA) and Pearson’s correlation were performed in order to compare PEN3 with TVB-N, and for the FOODsniffer evaluation, a one-way ANOVA was carried out. A significant correlation was shown between PEN3, first component, and TVB-N (r = 0.92, P=0.01). The ANOVA results also confirmed a good agreement between FOODsniffer, TVB-N (F = 519.9, P=0.01), and PEN3 (F = 143.17, P=0.01). Our simulation results confirmed good performance in both methods.

Effect of Antimicrobial Edible Coatings and Modified Atmosphere Packaging on the Microbiological Quality of Cold Stored Hake (Merluccius merluccius) Fillets

The effect of whey protein isolate (WPI) coatings incorporated with essential oils (EOs) and combined with modified atmosphere packaging (MAP) on the microbiological quality of fresh hake fillets was evaluated. Fresh hake fillets were coated with different formulations of WPI-EO coatings and packaged under air and MAP conditions (50% CO2/45% N2/5% O2). When WPI-enriched films were applied with or without the presence of MAP over hake fillets with a high initial microbial population, a limited but significant effect on the microbial growth was observed. This effect was more intense on Enterobacteriaceae and H2S-producing bacteria. When hake fillets with lower initial microbial counts were treated, a more intense antimicrobial effect was observed and a synergistic effect between WPI-EO coatings and MAP was detected. A significant extension of the lag phase and reduction, primarily, on the total viable counts and H2S-producing bacteria, was detected, doubling the shelf-life of hake fillets compared with control samples. The initial microbial load of the samples is a key factor influencing the effectiveness of the treatment. The obtained results demonstrated the effectiveness of this combined strategy as a promising alternative for enhancing the microbial quality of fish products during storage at refrigeration temperatures.

Assessment of high intensity ultrasound for surface decontamination of salmon (S. salar), mackerel (S. scombrus), cod (G. morhua) and hake (M. merluccius) fillets, and its impact on fish quality

Abstract The effect of applying high intensity ultrasound on microbiological and quality parameters in several fish species was assessed at laboratory scale. Samples of salmon ( S. salar ) and mackerel ( S. scombrus ) as oily fish, and cod ( G. morhua ) and hake ( M. merluccius ) as white fish, were treated using an ultrasonic bath (30 kHz). Samples of each species were separated into three groups (i) untreated control (C), (ii) water immersion only (IM) and (iii) ultrasound (US) and treated for 5, 15, 25, 35 and 45 min. All physicochemical parameters were determined in samples treated for 45 min. Microbiological counts were reduced significantly ( p p > 0.05) after treatment. Significant reductions of thiobarbituric acid reactive substances (TBARS) values (C: 0.36; US: 0.18) and colour changes were observed in salmon (a* C: 12.8; US: 10.0). Moisture levels increased by 8% following US treatment in hake.

Occurrence of Mislabelling in Prepared Fishery Products in Southern Italy.

Fish authentication is a major concern not only for the prevention of commercial fraud, but also for the assessment of safety risks deriving from the undeclared introduction of potentially dangerous toxic or allergenic substances or environmentally damaging fish where endangered species are involved. Moreover, food authentication might affect the diet of certain groups of consumers, such as followers of religious practices. Considering the authentication of fish products is one of the key issues in food safety, quality and sustainability, the aim of this work was to investigate the prevalence of mislabelling in sole (Solea solea), plaice (Pleuronectes platessa), Atlantic salmon (Salmo salar), and hake (Merluccius merluccius) fillets from markets and supermarkets located in Apulia (Southern Italy) using DNA barcoding. The results of the molecular investigations reveal that 42/98 (42.8%) fillet samples were not correctly labelled. In particular, 12/27 (44.4%) fillets of sole (Solea solea) were identified as belonging to Solea senegalensis. In addition, 13/28 (46.4%) plaice (Pleuronectes platessa) samples were identified as Pangasius hypophtalmus. All Atlantic salmon (Salmo salar) samples were correctly labelled. Post-sequencing data analysis revealed that 17/30 (56.6%) hake fillets (Merluccius merluccius) were not correctly labelled, of which 8/30 samples identified as Merluccius hubbsi, 5/30 samples as Merluccius products and 4/30 as Merluccius capensis. The study reveals a high occurrence of species mislabelling in the prepared fish fillet products, further evidence of the need for increased traceability and assessment of the authenticity of food products.

Contamination Predictions of Cape Hake Fillets during Display and Storage by Artificial Neural Network Modeling of Hexadecanoic Acid

This study aimed to design an artificial neural network (ANN) that could distinguish between Cape hake fillets displayed and stored on ice that have been exposed to excessive contamination and those that were not. The selected variable was a biochemical indicator, hexadecanoic acid, a fatty acid. Cape hake fillets with and without excessive contamination was kept on ice and analyzed every 48 h over a period of 10 days. A novel ANN was designed and applied, which provided an acceptable prediction on the contaminated fillets based only on the hexadecanoic acid changes during day 8 (T4) and day 10 (T5). The ANN consisted of a multilayered network with supervised training arranged into an ordered hierarchy of layers, in which connections were allowed only between nodes in immediately adjacent layers. The network consists of two inputs, T4 and T5 connected to two neurones that are connected to one output neuron that indicates a prediction on contamination of the fillets. These two neurons are connected to one output neuron that indicates a prediction on contamination of the fillets. Practical Applications The model sets the stage for the development of alternative quality control measures for retailers and buyers of fish and other foods that contain fatty acids such as hexadecanoic acid to provide saver food.