Quality Of Fish Fillets Research Articles

Fish Welfare – A Case Study: Reviling for the first-time side effects of vaccination in European sea bass (Dicentrarchus labrax) and barramundi (Lates calcarifer) in the Israeli fish farming

Vaccination is an effective way to control many infectious diseases in fish. Israeli fish farming has successfully used two vaccines over the last 30 years and has no problem with the side effects of vaccination. However, after introducing new species, a new problem emerged: these fish, after vaccination, demonstrated peritoneal lesions such as granulomas. At the same time, the fish did not show retarded growth or suffering during the fattening period. This study was conducted to establish the connection between vaccination and the appearance of granulomas. Evidence drawn from this research work and comparing vaccinated and non-vaccinated fish confirms that intraperitoneal granulomas do not impact the growth, performance, or fish fillet quality at harvest.

BIOLOGICAL AGENTS AS AN ALTERNATIVE TO CHEMICAL PRESERVATIVES IN THE SEAFOOD PROCESSING INDUSTRY, A REVIEW

The present research investigated the possibility of replacing probiotic bacteria instead of chemical preservatives in the seafood processing industry. The data were used from articles published in the databases including Science Direct, Pub Med, Scopus Springer Link, and Scopus. The search was carried out using the keywords fish fillet, beneficial non-dairy foods, increasing shelf life, biological protection, probiotic food, microbial treatment, and Lactobacillus bacteria. A biological preservation technique was used to maintain the quality of hake, spanish mackerel, mackerel, sea bass, tilapia, swordfish, rainbow trout, and ribbon fillets. Swordfish coated with L. paracasei IMPC 2.1 was acceptable for 3 months. Followed by spanish mackerel and rainbow trout fillets coated with L. casei and L. plantarum subsp. plantarum ranked second and third for 30 and 21 days, respectively. The minimum shelf life of fillets was 48 hours (Tilapia coated with L. plantarum 1.19). In freezing, L. brevis could maintain the quality of rainbow trout fillet for 6 months. The present study suggests Lactobacillus strains, especially L. paracasei IMPC 2.1, as a preservative to preserve the quality of fish fillets. However, the use of this species in the seafood processing industry requires wider research to investigate its effect on other aquatic species.

Seabream Quality Monitoring Throughout the Supply Chain Using a Portable Multispectral Imaging Device

Monitoring food quality throughout the supply chain in a rapid and cost-effective way allows on-time decision−making, reducing food waste, and increasing sustainability. A portable multispectral imaging sensor was used for the rapid prediction of microbiological quality of fish fillets. Seabream fillets, packaged either in aerobic or vacuum conditions, were collected from both aquaculture and retail stores, while images were also acquired both from the skin and the flesh side of the fish fillets. In parallel to image acquisition, the microbial quality was also estimated for each fish fillet. The data were used for the training of predictive artificial neural network (ANN) models for the estimation of total aerobic counts (TACs). Models were built separately for fish parts (i.e., skin, flesh) and packaging conditions and were validated using two approaches (i.e., validation with data partitioning and external validation using samples from retail stores). The performance of the ANN models for the validation set with data partitioning was similar for the data collected from the flesh (RMSE = 0.402–0.547) and the skin side (RMSE = 0.500–0.533) of the fish fillets. Similar performance also was obtained from validation of the models of the different packaging conditions (i.e., aerobic, vacuum). The prediction capability of the models combining both air and vacuum packaged samples (RMSE = 0.531) was slightly lower compared to the models trained and validated per packaging condition, individually (RMSE = 0.510, 0.516 in air and vacuum, respectively). The models tested with unknown samples (i.e., fish fillets from retail stores-external validation) showed poorer performance (RMSE = 1.061–1.414) compared to the models validated with data partitioning (RMSE = 0.402–0.547). Multispectral imaging sensor appeared to be efficient for the rapid assessment of the microbiological quality of fish fillets for all the different cases evaluated. Hence, these outcomes could be beneficial not only for the industry and food operators but also for the authorities and consumers.

Development of a water gradient film through film and ice-glazing approach utilizing konjac glucomannan and high acyl gellan gum for enhanced preservation of frozen snakehead (Channa argus) fillets

Fish fillets are perishable, and several commonly used preservation methods, such as freezing, ice-glazing, and plastic film packaging, aim to maintain their quality during frozen storage. This study presents a novel approach by developing a water gradient edible film using konjac glucomannan (KGM) and high acyl gellan gum (HAGG), and evaluates its effectiveness in preserving frozen snakehead (Channa argus) fillets. First, KGM/HAGG films with different weight ratios of KGM and HAGG were prepared and their properties were characterized. H-bond interactions occurred between KGM and HAGG, resulting in their compatibility and the formation of a homogeneous structure. The properties of the KGM/HAGG films, including tensile strength, elongation at break, water vapour permeability, oxygen permeability, and water swelling ratio, could be modified by changing the weight ratios of KGM and HAGG. The water gradient film was then prepared by adding water to one surface of the film, resulting in controlled swelling. This water gradient film exhibited a water gradient property before freezing and a combined film and ice-glazing property after freezing. It acted as both a moisture and oxygen barrier, while also acting as a moisture-sacrificing agent during frozen storage. When compared to unpackaged fillets, ice-glazed fillets, and fillets packaged with polyethylene film, the frozen water gradient film proved to be the most effective in preserving snakehead fillets during a 150-day frozen storage period. These findings indicate that the KGM/HAGG water gradient film could be a valuable alternative to conventional preservation methods for maintaining the quality of fish fillets during frozen storage.

Development of halochromic electrospun labels for non-invasive shelf life assessment of rainbow trout (Oncorhynchus mykiss): Incorporation of barberry anthocyanin extract in protein-based smart packaging.

Using barberry (Berberis vulgaris L.) as a natural dye in combination with electrospinning technology represents a promising approach for the development of intelligent packaging systems. In this study, the influence of different concentrations of zein (16, 18, and 20%) and barberry anthocyanin-rich powder (BARP) (16, 18, and 20%) on the surface tension and rheological properties of the solution were evaluated. The most favorable nanofibers (NFs) were obtained from a solution containing 18% (w/w) zein under constant voltage. The surface morphology, size, and color-changing properties of electrospun NFs derived from zein polymers containing different concentrations of BARP (16, 18, and 20%) under various electrical fields (20, 22, and 24 kV) were evaluated. The Fourier-transform infrared spectroscopy analysis confirmed the interaction of BARP within the zein-based NFs. The results indicated that the concentration of BARP had a noticeable impact on the physicochemical properties of the NFs. Furthermore, efficacy of the appropriately fabricated halochromic label was evaluated for monitoring the packed rainbow trout fillet during refrigerated storage. On the 10th day, a noticeable visual color turned from pink to pale yellow was observed in response to pH variations. Additionally, the TVN value confirmed the effectiveness of halochromic electrospun labels for non-invasive assessment of fish fillet quality.

The inhibitory action of lactocin 63 on deterioration of seabass (Lateolabrax japonicus) during chilled storage.

The bacteriocins, particularly derived from lactic acid bacteria, currently exhibit potential as a promising food preservative owing to their low toxicity and potent antimicrobial activity. This study aimed to evaluate the efficacy of lactocin 63, produced by Lactobacillus coryniformis, in inhibiting the deterioration of Lateolabrax japonicas during chilled storage, while also investigating its underlying inhibitory mechanism. The measurement of total viable count, biogenic amines, and volatile organic compounds were conducted, along with high-throughput sequencing and sensory evaluation. The findings demonstrated that treatment with lactocin 63 resulted in a notable retardation of bacterial growth in L. japonicas fish fillet during refrigerated storage compared with the water-treated and nisin-treated groups. Moreover, lactocin 63 effectively maintained the microbial flora balance in the fish fillet and inhibited the proliferation and metabolic activity of specific spoilage microorganisms, particularly Shewanella, Pseudomonas, and Acinetobacter. Furthermore, the production of unacceptable volatile organic compounds (e.g. 1-octen-3-ol, hexanal, nonanal), as well as the biogenic amines derived from the bacterial metabolism, could be hindered, thus preventing the degradation in the quality of fish fillets and sustaining relatively high sensory quality. The results of this study provide valuable theoretical support for the development and application of lactocin 63, or other bacteriocins derived from lactic acid bacteria, as potential bio-preservatives in aquatic food. © 2024 Society of Chemical Industry.

Bilayer coatings for extension of the shelf life of fish fillets: Incorporating seaweed sulfated polysaccharides in chitosan-alginate LbL structures.

The aim of this study was to develop a new active coating of layer-by-layer (LbL) structure composed of alginate (as polyanions) and chitosan (as a polycation) containing sulfated polysaccharide (fucoidan) from Sargassum angustifolium, to protect rainbow trout fillets during refrigerated storage. Chitosan and alginate do not combine with each other as a homogeneous solution, so they are suitable for multilayer coatings. The results demonstrated that coating samples with chitosan and fucoidan significantly improved the quality of fish fillets and extended their shelf life from 6 to 16 days. The chemical values (TBARS and TVB-N) and bacterial growth (total viable count (TVC), total psychrophilic count (PTC), and lactic acid bacteria (LAB)) indicated lower levels in the LbL coating samples containing fucoidan compared to the alginate and control samples. Among the different coating samples, the LbL coating with fucoidan (AChF1) exhibited lower weight loss, improved chromaticity (L*, a*, and b*), and minimal changes in mechanical and sensory evaluations. Based on the findings, AChF1 was the most effective treatment for increasing the shelf life of rainbow trout fillets during refrigerated storage. Therefore, it has potential applications in the food packaging industry.

Effect of climate change on fillet quality and shelf-life of Oncorhynchus mykiss under controlled conditions.

Temperature, which affects numerous physiological processes, has been described as the 'main ecological factor' for fish. The aim of this modeling study is to explore the impact of climate-induced temperature changes on fish fillet quality and shelf life. Temperature stress in rainbow trout affected ash and moisture, and inhibited myofibril fragmentation in the fillets. However, with the increase in temperature, there was a decrease in the total amount of saturated fatty acids (∑SFA) and there were significant increases in the total amount of omega 3 (∑n3) and 22:6n-3 (DHA). It was determined that temperature increase had a negative effect on color, texture, water-holding capacity, water activity, pH, lactic acid, and glycogen levels in fillets, and it had a positive effect by delaying microbial spoilage, especially in cold storage. This study suggest that the effects of climate change on product quality and shelf life in fish requires further research. It highlights knowledge gaps to guide future research in this emerging field. © 2023 Society of Chemical Industry.

Effects of natural compounds of some plants on microbial contamination and sensory quality of fish fillet during refrigeration

Effects of natural compounds of some plants on microbial contamination and sensory quality of fish fillet during refrigeration

Changes in quality and microbial diversity of refrigerated carp fillets treated by chitosan/zein bilayer film with curcumin/nisin-loaded pectin nanoparticles

The quality of freshwater fish is easy to deteriorate during postmortem storage, so it is necessary to find an effective method to extend the shelf life of fish fillets. The aim of this study is mainly to develop a novel bilayer active film with curcumin/nisin-loaded pectin nanoparticles (CZ-NPs) and evaluate its effect on the quality of fish fillets. The selected sensory, physicochemical (pH, color qualities, TVB-N, TBARS, biogenic amines, moisture state) and microbial properties (microbial enumeration and high-throughput sequencing) were analyzed to confirm the preservative mechanism of films on the fillets. During storage at 4 °C, better sensory evaluation feedback and lower total volatile base nitrogen in the film treated samples was observed when compared to the control samples. Additionally, CZ-NPs film effectively inhibited oxidation, with the final reductions of 1.04 mg MDA/kg flesh when compared to control. As suggested by low-field NMR and magnetic resonance imaging, film treated fillets presented higher water holding capacity by controlling transformation from immobilized to free water. Meanwhile, lower microbial enumerations were also recorded in the CZ-NPs film treated group, which was reduced by a range of 1.8–2.3 log CFU/g on day 10 when compared to control. High-throughput sequencing results showed that the Pseudomonas constituted the main spoilage bacteria of fillets, and CZ-NPs film contributed to the notably suppressed growth of Pseudomonas. As a result, CZ-NPs film showed a desirable application to extend the shelf life of refrigerated flesh, as an alternative for fishery product packaging and preservation.

THE EFFECT OF COLD CHAIN DISRUPTION ON THE MICROBIOLOGICAL PROFILE OF CHILLED FISH

Cold chain interruption during transport of samples to the laboratory may become a confounder in food hygiene practice. This study evaluates the influence of inadequate transport conditions on the microbiological quality of fish fillets from common carp (Cyprinus carpio), Atlantic salmon (Salmo salar), and Atlantic cod (Gadus morhua) packaged in plain, vacuum, or modified atmosphere packaging (MAP). The experiments simulated the temperature increase during sample transport to 3, 5, 8, 11, 14, 17, 20, and 25 °C with exposure times of 1, 2, 3, and 4 h. Aerobic plate count (APC), psychrotrophic microorganisms count (PMC), β-D-glucuronidase-positive Escherichia coli, and Salmonella spp. were evaluated immediately after the exposure to the elevated temperature (0 h), 3 h, and 24 h after the return to the normal temperature. Variability was observed even in the initial microbial contamination of fish fillets. Storage at higher temperatures led to an increase in microbial contamination of fish fillets Different types of packaging also played a role. In non-fatty fish (cod), CO2-containing MAP led to a decrease in pH and, therefore, to lower microbial growth. In fatty fish (salmon), the presence of CO2 did not lead to the reduction in pH and the degree of microbial contamination was, therefore, not affected by this intrinsic factor. If cold chain interruption occurs during the transport of samples to the laboratory, it is necessary to perform the analysis immediately as even storage in cold conditions until the next day can lead to increased levels of microbial contamination of such samples.

Plasma-activated water for disinfection and quality retention of sea bream fillets: Kinetic evaluation and process optimization

The efficacy of plasma-activated water (PAW) in the decontamination of sea bream fillets at various processing conditions including fish/immersion agent ratio (1/1–1/5) and immersion times (0–20 min), was evaluated. Deionized water (as control samples) and artificially produced water (artificial) with equal reactive species (H2O2, NO2−, and NO3−) concentrations to PAW were also used as immersion agents for comparison purposes. All the fillets were assessed in terms of their microbiological (total aerobic bacteria – TAB, yeasts/molds, hydrogen sulfide (H2S)-producing microorganisms, lactic acid bacteria – LAB, Pseudomonas spp., Brochotrix thermosphacta, and Enterobacteriaceae) and physicochemical (color, texture, lipid oxidation) characteristics. PAW-treated samples exhibited the highest microbial reduction; the loads of TAB, Pseudomonas spp., yeasts/molds, Enterobacteriaceae, H2S-producing bacteria and Brochotrix thermosphacta were reduced by approximately 1.58, 2.25, 3.95, 2.14, 1.96 and 1.48 logCFU/g, respectively compared to the fish initial natural microbiota (6.81, 6.25, 3.95, 5.14, 4.96 and 4.81 logCFU/g, respectively) at the most intense process conditions (fish/immersion agent ratio of 1/5 and immersion time of 20 min) (p < 0.05). Shelf-life study of all treated fillets was conducted to validate the efficiency of PAW. During 10-d storage at 4 °C, the PAW-processed sea bream fillets had lower microbial growth rates (i.e. for TAB growth, the rate was 0.440 d−1 for PAW-treated compared to 0.640 d−1 for untreated fillets) and retained their color and hardness, while total volatile basic nitrogen (TVB-N) remained at low levels (14.90 mg N/100 g) compared to the untreated ones (21.84 mg N/100 g). Their shelf-life was extended by approximately 60% and 30% for PAW- and artificially processed samples, respectively, (2.8- and 1.4-day shelf-life extension compared to control samples, respectively). These aforementioned data show that PAW can be efficiently used as a disinfectant agent to control microbial degradation, while retaining the quality of fish fillets. Industrial relevanceFish fillets are perishable food products, while none of the conventional or novel processing technologies or techniques may be applied for initial microbial population decrease. Storage and transportation at refrigeration temperatures below 1 °C (within Styrofoam insulated boxes full of ice flakes) is the target of the relevant companies for extending the shelf-life as much as possible.An alternative approach for reducing the initial microbial load and the microbial growth rate of fish fillets during storage and transportation is proposed, by immersing the fillets into Plasma activated water with antimicrobial properties. The microbial load is significantly reduced, resulting in a shelf-life extension by at least 60%. This allows for more distant transportation of the fillets and for less food waste since there is more time for consumption before spoilage.

Analysis of the water state and microfractal dimension of tilapia fillets during freezing and thawing.

To study the effects of freezing and thawing times and freezing temperatures on the water state and microstructure of tilapia fillets, experiments on tilapia fillets were carried out at -4 and -18°C with one to four freezing and thawing cycles (FTCs). Low-field nuclear magnetic resonance (LF-NMR) and nuclear magnetic resonance imaging were used to observe the water state after different treatments, and scanning electron microscopy (SEM) and frozen sections were used to observe the microstructure changes. Fractal dimension (FD) was used to quantitatively characterize the microstructure of the fish tissue, and the correlation between FD and fish fillet quality parameters was studied by principal component analysis (PCA). The findings showed that with the increase of FTCs, the thawing loss increased, and the water holding capacity (WHC) fell. FTCs cause a decrease in immobilized water and an increase in free water in the fillet. This indicates the migration of immobilized water to free water. SEM and frozen slice images showed that the growth of ice crystals led to the destruction of myogenic fibers. A decrease in freezing temperature inhibited ice crystal growth. The FD value dropped in accordance with an increase in FTCs. PCA demonstrated that the WHC, NMR data, and FD value had a strong correlation with the quality changes in the tilapia fillets. Therefore, FD and water state can reflect the quality characteristics of tilapia fillets. PRACTICAL APPLICATION: The water migration in tilapia fillets is detected with LF-NMR, and the microscopic image may be quantified using the FD value. Both approaches can offer fresh perspectives on how to assess the quality of tilapia fillets and reflect changes in their quality.

Does Dietary Lipid Level Affect the Quality of Triploid Rainbow Trout and How Should It Be Assessed?

Organoleptic properties and nutritional value are the most important characteristics of fish fillet quality, which can be determined by a series of quality evaluation indexes and closely related to fish nutrition. Systematic organoleptic and nutritional quality evaluation indexes consisting of 139 indexes for physical properties and chemical compositions of triploid rainbow trout were established. Besides, effects of dietary lipid levels (6.6%, 14.8%, 22.8% and 29.4%) on the quality of triploid rainbow trout were analyzed in the study. The main results showed that, for fillet appearance quality, fish fed diets with lipid levels above 22.8% had higher fillet thickness and redness but lower gutted yield and fillet yield (p < 0.05). For fillet texture, fish fed the diet with a 6.6% lipid level had the highest fillet hardness (5.59 N) and lowest adhesiveness (1.98 mJ) (p < 0.05), which could be related to lipid, glycogen, water soluble protein and collagen contents of the fish fillet. For fillet odor, the odor intensity of “green, fatty and fishy” significantly increased with the increase of the dietary lipid level (from 1400 to 2773 ng/g muscle; p < 0.05), which was related to the degradation of n-6 and n-9 fatty acids. For fillet taste, a high lipid diet (≥22.8%) could increase the umami taste compounds contents (from 114 to 261 mg/100 g muscle) but decrease the bitterness and sourness taste compounds contents (from 127 to 106 mg/100 g muscle and from 1468 to 1075 mg/100 g muscle, respectively) (p < 0.05). For nutritional value, a high lipid diet could increase the lipid nutrition level (such as the content of long chain polyunsaturated fatty acids increased from 3.47 to 4.41 g/kg muscle) but decease tryptophan and selenium content (from 2.48 to 1.60 g/kg muscle and from 0.17 to 0.11 g/kg muscle, respectively). In total, a high lipid diet could improve the quality of triploid rainbow trout. The minimum dietary lipid level for triploid rainbow trout should be 22.8% to keep the better organoleptic and nutritional quality.

Considering Two Aspects of Fish Welfare on African Catfish (Clarias gariepinus) Fillet throughout Postmortem Condition: Efficiency and Mechanisms.

Knowledge about fish welfare and its impact on fish fillet quality is still insufficient. Therefore, the influence of two aspects of fish welfare (slaughtering method: bled and unbled fish; fish stock densities: 90, 120, and 150 kg·m-3) on African catfish fillet quality during postmortem conditions was investigated. The aim of study was to determine (i) the efficiency of bleeding on oxidation progress and (ii) the influence of stock density on fillet quality. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed a higher protein loss in the unbled than in the bled groups, especially in the heavy myosin chain (MHC) band. However, density did not show any influence on protein profile. Western blot analysis showed fewer oxidized carbonyls in the bled than in the unbled groups; higher oxidation development, microbial growth, and lower hardness were observed in unbled fillets. Additionally, hardness was higher at 90 and 120 kg·m-3 densities in bled fillet compared to 150 kg·m-3. The first three days of storage showed a higher oxidation rate in unbled fillets than in bled fillets, confirming the contribution of hemoglobin to oxidation development with different mechanisms of protein oxidation. The obtained results revealed the same fillet quality in all aspects at either 90 or 120 (kg·m-3) stock densities, which would suggest 120 kg·m-3 for the fishery industry. However, higher stocking density in this study would not be appropriate for fish welfare.

Ultrasound-reinforced encapsulation of proanthocyanidin by chitosan-chondroitin sulfate nanosystem

The polyelectrolyte complexation between chitosan (CH) and chondroitin sulfate (CS) and the ultrasonication assistance were adopted as the encapsulation strategy for preparing proanthocyanidin (PC) encapsulated nanoparticles (NPs) to protect bio-functions of PC. Conditions of 1.5 mg/mL of CH and CS, 1:3 wt ratio of CH/CS, 0.5 mg/mL of PC, pH 3.25, and 1 min ultrasonic treatment were recommended by the systematic research, respectively, with NPs appearing the smallest size (∼300 nm) and high entrapment efficiency (37.5%). Ultrasound crushed aggregates into nanoparticles by the acoustic cavitation and generated more amide bonds observed by XPS. Due to the physical barrier of NPs, PC in NPs still had a 94.4% DPPH radical scavenging rate after illumination of 10 d. Application of NPs for fabricating CH bio-films was carried out, and the bio-films containing CH/CS-PC NPs decreased aerobic bacteria count and lipid oxidation of fillets stored for 8 d by 2.2 log 10 CFU/g and 51.1%, respectively, which was better than pure CH bio-films. The incorporation of PC-encapsulated NPs to CH bio-films inhibited the bacteria and oxidation induced spoilage for refrigerated grass carp flesh, providing a potential application for food preservation. • Chitosan and chondroitin sulfate formed nanoparticles to load proanthocyanidin. • Ultrasound reduced the size of particles and created more amide bonds. • The encapsulation for proanthocyanidin maintained the antioxidant effect. • Nanoparticle-contained films enhanced the quality of fish fillets during storage.

Characterization of different phenolic acids grafted chitosan and their application for Japanese sea bass (Lateolabrax japonicus) fillets preservation

The characterization of chitosan graft different phenolic acids (CS-g-phenolic acids) and the preservation effect on sea bass (Lateolabrax japonicus) was investigated. Caffeic acid (CA), gallic acid (GA) and chlorogenic acid (CHA) were respectively grafted onto CS by carbodiimide coupling method. The results of fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H NMR) and ultraviolet–visible spectrophotometry (UV–vis) indicated that CA, GA and CHA grafted onto CS were successfully. The DPPH scavenging activity and antibacterial diameter of CS-g-phenolic acids were higher than those of CS, illustrating that grafting with phenolic acid effectively enhanced the antioxidant and antibacterial capacity of CS. Meanwhile, the preservation effects of these three CS-g-phenolic acids on sea bass during storage at 4 °C was studied. Results shown that CS-g-phenolic acid could significantly inhibit the growth of microorganisms, reduce the production of total volatile basic nitrogen (TVB-N), prevent lipid oxidation, delay water migration, and maintain good sensory quality of fish fillets during storage. Overall, CS-g-phenolic acid can effectively maintain the quality of sea bass during storage and extend the shelf life of sea bass by another 6 days. These findings will provide a theoretical basis for the application of CS-g-phenolic acids in seafood preservation.

Ultrasound assisted treatment improves the preservation performance of chitosan-grafted-chlorogenic acid on refrigerated sea bass (Lateolabrax japonicus) fillets.

Ultrasound can increase the mass transfer between preservatives and food, and enhances the effect of preservatives on food. Chitosan-grafted-chlorogenic acid (CS-g-CA) is a new synthetic compound with good antiseptic properties. Therefore, the present study evaluated the preservation performance of ultrasound-assisted CS-g-CA (GUA) coatings on refrigerated sea bass fillets in terms of changes in microorganisms, lipids, proteins, tissue structures, and moisture. The results showed that GUA treatment effectively inhibited the growth of microorganisms in sea bass fillets. Meanwhile, the changes in total volatile basal nitrogen, thiobarbituric acid reactive substances, and pH values were all slowed down under GUA treatment, indicating that protein degradation and lipid oxidation in sea bass were inhibited. Low-field nuclear magnetic resonance and magnetic resonance imaging results indicated that the GUA retarded the conversion of mobile water to free water. In addition, GUA treatment maintained the flavor quality of fish fillets, and also inhibited the reduction of inosine monophosphate and the production of bitter substances (inosine and hypoxanthine), suppressed muscle tissue degeneration, and maintained better sensory scores. Overall, GUA treatment inhibited microbial growth, protein degradation, lipid oxidation, moisture migration, decomposition of umami substances, and deterioration of sensory quality in sea bass fillets. Finally, the shelf-life of sea bass fillets with GUA treatment was extended by an additional 9 days. The results showed that ultrasonic assistance further enhanced the effect of preservatives on aquatic products. © 2022 Society of Chemical Industry.

The Combined Effects of Bio-Components and Alginate Coating on Chemical and Sensory Quality of Chill-Stored Rainbow Trout Fillets

ABSTRACT The objective of the present study was to reduce lipid oxidation and preserve sensory quality of fish fillets maintained under refrigerator condition. The lactoperoxidase system (LPOS) or Zataria multiflora Boiss essential oil (ZEO) was added individually or in combination in biodegradable coatings. Fish fillets were analyzed for peroxide value (PV), free fatty acid value (FFA), fatty acid profile, thiobarbituric acid reactive substances (TBARS) value, and sensory evaluation. Suppressive effect of ZEO and LPOS was seen in the combined groups; so that PV value ranged from 0.32 (0 day) and 0.41 (4 day) meq/kg to 1.97 meq/kg on day 8. The lowest amount of TBARS (1.54 mg MDA/kg) and FFA (1.84% of oleic acid) was obtained in the samples treated with alginate coating containing LPOS and ZEO 1% at the end of storage. The use of ZEO and natural preservatives such as LPOS is presented as alternatives to chemical preservatives in seafood.

Effect of fish diet and cooking mode on the composition and microstructure of ready-to-eat fish fillets of gilthead sea bream (Sparus aurata) juveniles

The effect of fish diet and cooking modality was described for Gilthead sea bream juveniles (Sparus aurata). Three feeds were tested: a control diet containing fish meal (FM>26%) and fish oil (FO>6%) and two diets where FM and FO were replaced with more sustainable alternatives (FM<14%; FO<5%). Fillets were analyzed raw and after cooking at increasing intensities: sous-vide, boiling, roasting and microwave oven baking. The overall quality of fish fillets was assessed by measuring their appearance by Image Analysis, by characterizing their proximate composition, fatty acid profiles, quality indices, and their microstructural features by Magnetic Resonance Imaging and relaxometry. The analysis of experimental data suggested that fish diet specifically characterized the nutritional quality of cooked fillets by affecting their fatty acid profiles, irrespective of the cooking process. Appearance (color, image texture) and muscle microstructure were only influenced by the intensity of cooking, regardless of diet. As cooking intensity increased, water and oil distribution in myofibrils was progressively reorganized and muscle fibers shrunk, causing relevant microstructural changes, especially in roasted and microwave oven baked fillets. The paper provides a useful guide for the production of ready-to-eat meals derived from sustainable aquaculture processes and characterized by high sensory and nutritional quality.