Fish Fillets Research Articles

Toward Classification of Fish Meat Using Fluorescence Excitation–Emission Matrix and Multivariate Statistics

Frequent intentional mislabeling of particular fish and fish products, such as the sale of frozen and thawed fish instead of fresh fish, occurs on all continents. Therefore, two studies were conducted to classify fish meat using excitation–emission matrix (EEM) nondestructively. The first study assessed EEM for differentiation between fresh and frozen–thawed spotted mackerel fillets. Fresh fillets were yielded with different post-mortem freshness variations (ice storage for 0–40 h). The right-side fillets were used as fresh fillets, whereas the left-side fillets were frozen and stored at −30 °C for three months, then thawed at 4 °C. Subsequently, EEM acquisition and chemical analyses were performed. Results of principal component analysis (PCA) of EEM spectra showed clear discrimination between fresh and frozen–thawed meat of fish fillet. In the second study, post-mortem freshness variations in four fish species (horse mackerel, spotted mackerel, cod, and flounder) were simulated by ice storage (0–48 h) and subsequent freezing. PCA of the EEM demonstrated a clear distinction among the fish meat categories, which was also revealed from the freshness data of chemical analysis. Results show that this novel method can be used to monitor fishery product authenticity.

Antibacterial mechanism of vitamin K3-mediated photodynamic inactivation against Pseudomonas fluorescens and its influences on blunt bream (Megalobrama amblycephala) quality

Photodynamic inactivation (PDI) has emerged as a novel non-thermal process technology for inactivating microorganisms due to its low cost, safety, and efficiency. This study aimed to investigate the antimicrobial effect of VK3-mediated PDI against Pseudomonas fluorescens (P. fluorescens) and to assess its impact on the quality of the blunt bream contaminated with P. fluorescens. The inhibition efficiency and photosensitization mechanism were investigated under different VK3 concentrations and UV-A light time conditions. The results showed that PDI could significantly inactivate P. fluorescens >7.0 log10 cfu/ml with 1 mM VK3 and 45 min of UV-A irradiation. Type I and type II photoresponses could co-occur in VK3-mediated PDI by quantitatively analyzing the photoresponse product ROS (OH, H2O2, 1O2). It was observed by SEM and TEM that the combined treatment of VK3 and UV-A disrupted the cellular integrity of P. fluorescens, leading to leakage of cell contents. Meanwhile, it degraded intracellular proteins and destroys genomic DNA, ultimately leading to bacterial death. In addition, the PDI system slowed down P. fluorescens’ proliferation during the blunt bream storage at 4 °C. The PDI system effectively killed 59 % of P. fluorescens on the blunt bream fillets under 1.5 mM VK3 and 60 min of UV-A irradiation. The VK3-mediated PDI delayed pH change and TVB-N production, inhibited protein degradation and fat oxidation, and ultimately maintained the quality of fish fillets. This study provides a promising PDI system for controlling food microbial contamination and maintaining the storage quality of aquatic products.

Immersion frozen storage combined with silver carp muscle hydrolysate: Effects on freshness, protein properties and microstructure of cryopreserved grass carp

This study highlighted the combined effects of immersion frozen storage (IFS) and silver carp muscle hydrolysate (SCMH) on the quality of cryopreserved grass carp. The fish fillets were pretreated with SCMH and stored at −18 °C using an indirect IFS method (SCMH + IFS), which offered rapid freezing and reduced temperature fluctuations (±0.4 °C), and changes in freshness, protein properties and muscle structure were evaluated over a 60-day storage period. Compared to IFS alone or traditional air frozen storage (AFS), samples treated with SCMH + IFS showed lower increases in K value (from 10.4% to 33.9%), TVB-N (from 7.3 mg/100g to 15.1 mg/100g), as well as retarded changes in the solubility, Ca2+-ATPase activity, surface hydrophobicity, and sulfhydryl content of myofibrillar protein. Furthermore, the ice formation and recrystallization as well as the physical damages to fish muscle myofibril structure were markedly mitigated in the SCMH + IFS samples. Therefore, SCMH + IFS was a promising approach for enhancing the quality of cryopreserved fish products.

The enhanced antibacterial effect and mechanism of PostbioYDFF-3 against Pseudomonas putida NBRC 14164 and Acinetobacter johnsonii ANC 3681

The inhibitory mechanism of postbioYDFF-3 (postbiotics) on Pseudomonas putida NBRC 14164 (P. putida NBRC 14164) and Acinetobacter johnsonii ANC 3681 (A. johnsonii ANC 3681) in refrigerated fish fillet was investigated. At the cellular level, the minimum inhibitory concentrations of P. putida NBRC 14164 and A. johnsonii ANC 3681 treated with postbiotics were 3.9063 μL/mL and 15.625 μL/mL, respectively. The postbiotics effectively inhibited biofilm formation, promoted cell DNA leakage and increased cellular membrane permeability. Furthermore, the transcriptomic results showed that the pathways of transmembrane transport, energy metabolism, DNA damage repair, nucleotide binding and oxidation-reduction (REDOX) were significantly down-regulated. In particular, PhnA and A1_GM000335 genes were up-regulated by 9.71 and 7.16 times respectively, which was the key to stress response in the nucleotide binding pathway of A. johnsonii ANC 3681. PP4_RS22590 and katE genes were down-regulated by 28.64 and 11.63 times respectively, which caused the REDOX inhibition of P. putida NBRC 14164. The transcriptomic results were verified by quantitative real-time PCR (qRT-PCR). This study provided a new theoretical basis for the inhibition of postbiotics against P. putida NBRC 14164 and A. johnsonii ANC 3681.

Antibacterial Effects of Zinc Oxide Nanoparticle and Ginger Oil Nanoemulsion in Fish Fillet Keeping Quality

Antibacterial Effects of Zinc Oxide Nanoparticle and Ginger Oil Nanoemulsion in Fish Fillet Keeping Quality

A holo-omics analysis shows how sugar kelp can boost gut health in Atlantic salmon

The projected growth of Aquaculture requires continuous optimisation of feeding regimes, especially in enhancing disease resilience through immunostimulating feed supplements. Seaweed has been introduced as a promising supplement due to its proposed immunostimulant effects, while mitigating carbon emissions and marine eutrophication. Two separate growth trials were performed to evaluate the effects of a seaweed supplement, focusing on a closed land-based RAS system with fish growing from ∼300–600 g and an open water net-based trial with fish growing from ∼500–2500 g. A multi-omics approach was taken to investigate the effect of using up to 2 % fermented sugar kelp (Saccharina latissima) as a supplement on the growth performance and gut health of Atlantic salmon (Salmo salar L.). Standard growth metrics and quality indicators were coupled with multi-omics data for the host intestinal transcriptome, intestinal metabolome, and intestinal microbiome. Levels of iodine and heavy metals in the fish fillets resulting from seaweed inclusion were evaluated. Seaweed additives up to 2 % had no negative impact on the salmon growth performance or other health parameters. While concentration of iodine increased with seaweed addition, all levels remain below recommended thresholds. Furthermore, gut transcriptome analyses of 179 individuals revealed multiple indications for an immunostimulant effect of seaweed, including overexpression of the mucin biosynthesis and pyrimidine metabolism pathways related to mucus production and intestinal homeostasis. Genome-resolved metagenomics revealed a core microbiome dominated by Mycoplasma, Photobacterium, and Brevinema species. Interestingly, the assembled genomes of these three core species had consistently higher levels of genome erosion and gene loss compared to other present species suggesting host adaptation. Further, reduced prevalence of known pathogens such as Aliivibrio highlights a potential protective effect of seaweed by impeding growth of opportunistic pathogens. Results suggest that supplementation of up to 2 % fermented seaweed can increase feed efficiency, stabilise the intestinal microbiome and potentially increase resistance against known pathogenic bacteria including Aliivibrio species.

Complete replacement of fishmeal with unconventional animal protein sources: A comparative study of the effects of use of mealworm, earthworm and zooplankton on growth parameters, fatty acid composition and sensory profile rainbow trout

The global trend in aquaculture is to replace fishmeal with an alternative and sustainable source of protein for fish farming. As a result, some species of invertebrates have found a place in aquaculture as a rich source of protein and a promising substitute for fishmeal. This study aimed to investigate the effects of alternative protein sources on the growth parameters of rainbow trout (Oncorhynchus mykiss) as well as the fatty acid profile and the sensory quality of the fish fillets. The gas chromatography technique with a flame ionization detector was used to determine the fatty acid composition of the rainbow trout fillets, while different equations were used to determine the growth parameters and the hepatosomatic index. The sensory evaluation of the rainbow trout fillet was determined by a descriptive sensory analysis, a quality assessment and a consumer acceptance test. The replacement of fishmeal by mealworms (MWD) and earthworms (EWD) resulted in a positive effect on growth parameters, feed conversion, and hepatosomatic index (HSI) values. The mortallity of the rainbow trout fed with the experimental diets was less than 28 %. The eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) content of the trout fillets decreased with the inclusion of MWD (1.34 and 5.20 %, respectively) and EWD (1.74 and 6.41 %, respectively) in the trout diet. Feeding rainbow trout with MWD and EWD caused a decrease in the n-3/n-6 ratio compared to FMD (0.32 and 0.34, respectively vs. 0.56), whereas the addition of ZOD resulted in the increase of the n-3/n-6 ratio (0.67). The samples of fillets of trout fed with MWD and EWD belonged to the "very good" level of average sensory quality, while the fillets of trout fed with zooplankton were in the "good" quality range. Regarding acceptability by consumers all rainbow trout fillets shown good consumer acceptance.

Development of pH-Sensitive intelligent films incorporating betacyanin from dragon fruit peel and TiO2 nanoparticles for monitoring fish fillet freshness

This study aimed to develop novel pH-sensitive intelligent films for monitoring food freshness by incorporating betacyanin extracted from dragon fruit peel, pectin, sodium alginate, and titanium dioxide (TiO2) nanoparticles. Pectin and betacyanin were simultaneously extracted from dragon fruit peel and combined with sodium alginate and TiO2 nanoparticles to create composite and double-layer films. The films were comprehensively characterized to evaluate their physical, mechanical, structural, and functional properties. Additionally, their effectiveness in monitoring the freshness of mackerel fillets was assessed. The incorporation of TiO2 nanoparticles significantly enhanced film properties, with tensile strength increasing from 3.55-13.42 MPa to 13.85–14.90 MPa, water vapor permeability decreasing from 1.58 to 3.00 × 10−9 g/msPa to 1.54–3.00 × 10−9 g/msPa, and swelling degree reducing from 294-330% to 260–261%. TiO2 nanoparticles effectively immobilized and protected betacyanin from photodegradation, crucial for maintaining color stability. The subjected films demonstrated color changes from reddish-violet to brownish-yellow, correlating with increasing TVB-N levels in mackerel fillets. The double-layer film exhibited superior stability under both dark and light conditions compared to the composite film. This study uniquely combines dragon fruit peel-derived pectin and betacyanin with TiO2 nanoparticles, addressing the growing demand for eco-friendly packaging solutions by utilizing food waste and developing biodegradable alternatives to synthetic pH indicators.

Effects of cold plasma-activated solution on microbial amounts and diversity of Tilapia fillets at refrigerator storage

In this study, tilapia fillets were treated with the plasma-activated solution and refrigerated at 4 ± 1 °C. Compared with the distilled water group, plasma-activated lactic acid (PALA) treatment prolonged the microbiological shelf life of fish fillets by 4 d. The total bacterial count, psychrophilic bacteria, Pseudomonas spp., H2S-producing bacteria, and lactic acid bacteria in the PALA group were lower than those in the other treatment groups (P < 0.05). High-throughput sequencing indicated that Proteobacteria and Firmicutes were the two predominant core microbial phyla present during storage. In the first 5 d of storage, Acinetobacter, Kurthia, and Shewanella were the dominant genera. At the 7th d of storage, the spoilage bacteria Aeromonas and Pseudomonas increased slightly. These mechanistic results demonstrate that cold plasma solution treatment allows tilapia fillets to be stored under refrigeration for up to 7 d. Cold plasma solutions have potential applications in fish fillet refrigeration.

Heat Penetration Characteristics and Quality Evaluation of Pangasius (Pangasius hypophthalmus) Chunks in Masala Using Retort Pouches

A South Indian dish was developed using Pangasius fish (Pangasius hypophthalmus) fillet chunks in masalas as a medium. The aim of the current study was to optimize the various F₀ values for Pangasius fillet chunks packed in masala, using flexible, retortable pouches. After being processed at different lethality levels, the product showed a similar heating and cooling lag factor. For F₀ values of 7.37 and 8.12 minutes, the total process time were 26.94 and 31.37 minutes, respectively. The fh values for products processed at F₀ values of 7.37 and 8.12 minutes were 13 and 16.5 minutes, respectively. The cook value obtained for the thermally processed product was 64.70 minutes for F₀ 7.37 minutes and 65.87 minutes for F₀ 8.12 minutes. Over a storage duration of up to 90 days, all instrumental texture indicators exhibited a declining pattern. The product processed at Fo value of 7.37 and 8.12 minutes were achieved commercial sterility. The product processed at F₀ 7.37 minutes was considered more favourable based on organoleptic assessment.

Green Packaging Solutions for Extending the Shelf Life of Fish Fillet: Development and Evaluation of Cinnamon Essential Oil-Infused Cassava Starch and Fish Gelatin Edible Films.

Edible, eco-friendly films made from cassava starch, cinnamon essential oil (CEO), and fish gelatin have been shown to extend the shelf life of fish fillets. These biodegradable films offer an environmentally friendly alternative to conventional plastic packaging. This study explores the production of edible films using cassava starch, fish gelatin from processing waste, and CEO nanoemulsion (CEON), focusing on their physical, mechanical, antioxidant, and antibacterial properties. The optimal film blend, consisting of 5% cassava starch and a 1:3 ratio of fish gelatin with 10% CEON (SGCEON3), demonstrated excellent antioxidant and antibacterial properties, extending the fish fillet shelf life to 10 days. These films were light brown with increased thickness (0.19 ± 0.001 mm), tensile strength (20.15 MPa), and elongation at break (270.50%). The TGA analysis showed a consistent mass loss from 30 to 600 °C, and AFM results indicated an average height deviation of 39.925 nm, a roughness of 54.439 nm, a surface symmetry skewness of 0.860, and a kurtosis of 1.77. The FE-SEM images and FTIR spectra confirmed compatibility between fish gelatin and CEON. The migration assay observed a more gradual and constant release of the CEO from the SG films, and the SGCEON3 film is suitable as an antimicrobial packaging material. This study highlights the potential of biopolymer packaging infused with essential oils to extend the shelf life of perishable foods effectively.

Protective effects of Bacillus velezensis on texture, physicochemical properties, and lipid oxidation of grass carp fillets during repeated freeze-thaw cycles.

Probiotics have excellent antioxidant and antibacterial effects and are also considered to be promising natural biological preservatives. This study examined the freeze-thaw stability of the antioxidant and antibacterial activity of probiotic Bacillus velezensis PJP10, and evaluated the effect of different concentrations of PJP10 (106, 107, and 108 CFU mL-1) on microbial growth, textural characteristics, physicochemical properties, and lipid oxidation of grass carp fillets during repeated freeze-thaw cycles. Freeze-thaw cycles had little effect on the antioxidant and antibacterial stability of PJP10. Treatment with the PJP10 strain slowed effectively the increase in Aeromonas spp. counts (ASC), pH, total volatile basal nitrogen (TVB-N), and thiobarbituric acid (TBA) values of the freeze-thaw fish fillets. It maintained the textural quality of fillets, inhibiting the reduction of hardness, springiness, gumminess, cohesiveness, chewiness, and resilience values, and reduced lipid oxidation, as evidenced by decreased carbonyl values and conjugated diene values after multiple freeze-thaw cycles. Probiotic B. velezensis PJP10 had protective effects on microbiological, textural, and physicochemical properties, and lipid oxidation of grass carp fillets during repeated freeze-thaw storage, suggesting a potential application of this strain in the freeze-thaw preservation of freshwater fish. © 2024 Society of Chemical Industry.

Dietary Malondialdehyde Impair Intestinal Health and Fillet Quality of Hybrid Grouper (Epinephelus fuscoguttatus♀ × E. lanceolatus♂).

Aquafeed kept at elevated temperatures and humidity can result in malondialdehyde (MDA) formation, adversely affecting aquafeed quality and triggering negative reactions in fish. To investigate the detrimental effects of dietary MDA on fish, six experimental diets with varying MDA levels (ranging from 0.03 to 17.72 mg/kg, on dietary crude lipid basis) were administered to three replicates of hybrid grouper for 8 weeks. Dietary inclusion of 4.43 mg/kg MDA significantly decreased serum complement 4 content and lysozyme activity, along with intestinal complement 3, complement 4, and immunoglobulin M contents. Furthermore, dietary inclusion of 8.86 mg/kg MDA significantly increased the activities of interleukin-1 receptor-associated kinase, ubiquitin-protein ligase, p38 mitogen-activated protein kinase, and tumor necrosis factor-α, downregulated the relative expression of Occludin but upregulated the relative expression of HSP70 in the hindgut. Additionally, the highest inclusion of MDA (17.72 mg/kg) significantly upregulated the relative levels of pro-inflammatory cytokines (IL-1β and TNF-α), caused intestinal inflammation, and damaged the intestinal microbial structure and fish fillet texture. This study demonstrated a dose-dependent response of MDA on hybrid grouper. A low dietary dose of MDA (<2.21 mg/kg) exhibited minimal impact on immune response and fillet quality. However, higher inclusion levels (≥4.43 mg/kg) impaired the intestinal health and fillet quality. Consequently, the safety limit for MDA content in the diet for hybrid grouper has been established at 4.43 mg/kg based on dietary crude lipid basis.

Investigation of the Storage Temperature Effect on Phthalate Migration Potential in Vacuum‐Packed Fish Fillets

Investigation of the Storage Temperature Effect on Phthalate Migration Potential in Vacuum‐Packed Fish Fillets

Enhancing local gastronomy: Innovative preparations with coró Fish (Pomadasys corvinaeformis) on the coast of Northeast Brazil

Fishing is an important economic activity for the coastal regions of Brazil. This study aims to analyze the proximate composition of coró fish (Pomadasys corvinaeformis) and develop new preparations using this fish, common on the coast of the state of Ceará, in the municipality of Camocim. The methodology included analysis of the proximate composition of the fish filet, development of culinary preparations, microbiological analysis and sensory evaluation of the products prepared. Two preparations were developed: a coró cake and a coró cream, both subjected to microbiological and acceptance analysis. The coró filet is rich in protein and has a moderate lipid content, comparable to other fish species consumed in the region. The sensory analysis, carried out with focus groups from the fishing community and the general population of Camocim, revealed a high acceptance of the preparations, with a preference for coró cream. The analysis highlighted the importance of the characteristic flavor of coró in the preparations and suggested improvements, such as adjustments to the texture and color of the coró cake. Hence, the potential of coró as an important source of nutrients and an element of local gastronomy enhancements is emphasized. The preparations presented an alternative to diversifying the use of fish in regional cuisine and reinforcing Camocim's cultural food identity. The study suggests continuing research in the area, developing educational materials on food sovereignty, and incorporating traditional foods into the school curriculum as strategies to promote the appreciation of local products and the nutritional health of the population.

Cellulose-based halochromic sensor for real-time surveillance of spoilage of packed fish

The development of a biopolymer-based color-changing visual sensor for monitoring the spoilage of fishery products is described in this study. At first, a cellulose-based composite film containing mixed-indicator dyes was fabricated. The film was characterized using UV–visible and FT-IR spectroscopy, scanning electron microscopy, thermogravimetric analysis, lab, and RGB measurements. The halochromic properties of the film were evaluated through ammonia test and colorimetry. The developed film sensor is tested for monitoring the spoilage of packed seer fish fillets at room temperature for up to 48 h and at 4 °C for up to 10 days. The sensor displayed distinct color changes correlating with the spoilage of the packed fish. Analysis of total volatile basic nitrogen and pH levels of the samples revealed a correlation between the halochromism of the sensor and the spoilage of the fish. The color-changing pattern of the sensor was consistent with the results of microbial analysis. The present study reveals a promising material combination for fabricating simple visual sensors from biomaterials, which can be used to monitor the real-time deterioration of packaged fishery products.

A comparative study of chemical composition, the level of fatty acids, amino acids and mineral elements between two types of catfish (Bagrus and Muraena) found in the upper Tigris River

Fish meat is considered the second most interesting to consume in Iraq hence, consumers always consider the sensory and nutritional profile of the fish meat. The study aimed to investigate the chemical composition and level of fatty acids and amino acids in Bagrus and Muraena fish fillets. These fish for this study were obtained from the upper Tigris river in the Tikrit region of Iraq, as the demand for these types of fish increased in recent years. In this work, High Performance Liquid Chromatography −UV (HPLC-UV) was used for quantification of amino acids, and atomic absorption was used for quantifying the elements. The extraction was performed by liquid –liquid extraction and purified by dispersive phase purification. Results showed that the moisture percentages in Bagrus meat were 71.36 %, while Muraena meat recorded as 71.10 %. Moreover, the protein percentages for both fish types were found as 21.36 and 21.43 % respectively. Lipid percentages in fillets of Bagrus and Muraena were 3.59 and 4.62 %, respectively. The proportion of ash was 3.01 % in Bagrus meat, while it was 2.55 % in Muraena meat. The results also presented that the Muraena has a significantly higher saturated fatty acid level (26.06 %), whereas in Bagrus meat was much less (16.6 %). The highest percentage of amino acids in Bagrus meat recorded (92.66 %), while it was 61.94 % in Muraena meat. The Bagrus meat contained essential amino acids with a higher percentage (54.04 %), compared to Muraena meat (28.55 %), non-essential Amino acids percentage also reached 47.56 % in Bagrus fish fillets. The amino acids like alanine had recorded the highest percentage among non-essential amino acids, as its level resulted in 38.62 %, while the level (33.39 %) was lower in Muraena meat.

Violation of the Brazilian moratorium on the catfish piracatinga (Calophysus macropterus): genetic evidence of mislabeling and toxicological hazard to deceived consumers

The piracatinga (Calophysus macropterus) is a scavenger catfish from the Amazon and Orinoco River basins and its fishery has relied on the intentional killing of river dolphins and caimans for use as bait, mainly in the central Amazon. A previous genetic study revealed that piracatinga were being sold in Brazil as processed fillets labeled with fictitious names to deceive consumers. Due to the unsustainable impact on river dolphin populations, and to the threat to human health posed by the consumption of this mercury-rich species, Brazilian authorities issued on 2015 a 5-year moratorium on the fishing, storage and trade of piracatinga. This study presents a synthesis of two conducted research efforts. The first reported on the results of genetic and toxicological analyses of fish fillets labeled as Surubim (Pseudoplatystoma fasciatum), dourada (Brachyplatystoma rousseauxii) and piramutaba (Brachyplatystoma vaillantii), purchased from supermarkets in Manaus. Genetic analysis revealed that 89% of these samples were genetically identified as C. macropterus and mislabeling involving this and other species was revealed in 100% of fillets from supermarkets. Total mercury concentration in genetically identified C. macropterus fillets were above the safe limit for predatory fish set by FAO (1.0 mg. kg-1) in 44% of the fillets, ranging from 0.27 to 1.92 mg. kg-1. The second study reported on the genetic analysis of fish fillets labeled as Piramutaba (Brachyplatystoma vaillantii), Piranambu (Pirinampus pirinampu) and Mapará (Hypophthalmus edentatus) apprehended during surveillance operations at fish-processing plants in the cities of Iranduba and Manacapuru, both near Manaus, and suspect fish fillets offered as meals in a public school in Manaus. Genetic analysis revealed that 9% of these samples were C. macropterus. All samples were collected during the moratorium (2017-2019; N = 133). Our results revealed that despite the moratorium, the piracatinga continued to be fished and commercialized, and consequently it was not as effective as needed to reduce the impact of the illegal fishery over dolphin and caiman populations. Additionally, the inadvertent consumption of piracatinga is a health risk for humans, who may become intoxicated even with small weekly uptakes of this fish.

Optical evaluation of internal meat quality deterioration in a tuna fillet based on second-harmonic generation anisotropy measurement

Methods for evaluating fish freshness have transitioned toward non-invasive, non-destructive, and non-contact approaches. However, non-contact methods for texture assessment that usually require contact for measurement remain limited. This study proposes a new non-contact method to quantify muscle degradation, which is thought to reflect fish meat texture, using optical methods. Second-harmonic generation (SHG) is a non-linear light scattering process. The anisotropy of SHG light reflects the structural conditions in muscle myosin filament and collagen fibers that directly contribute to the texture of fish meat. This study assessed the feasibility of using SHG anisotropy measurements to evaluate muscle degradation in fish fillets during chilled storage. Analyses of the SHG intensity and anisotropy scattered from a tuna fillet successfully identified three degradation processes with turning points at 24 and 72 h after thawing. This study clearly demonstrates that SHG anisotropy measurements have potential as a standard for fish quality evaluation.

The active kappa-carrageenan coating and oxygen absorber packaging for the preservation of chilled rainbow trout fillets

The objective of the current research was to evaluate the effects of incorporating kappa-carrageenan (KCA) coating with dill essential oil (DEO), in conjunction with oxygen absorber (OA) packaging, on the quality attributes of rainbow trout fillets throughout a 20-day period of refrigerated storage. The administered treatments included OA, KCA + OA, KCA + DEO, KCA + DEO + OA, and control. Treating the trout fillets with DEO-loaded coating and/or using OA packaging was found to be more effective in restricting the growth of total mesophilic and psychrotrophic bacteria, Enterobacteriaceae, and lactic acid bacteria. The aforementioned treatments were more efficient in slowing down the rate of increase in pH, total volatile nitrogen, conjugated dienes, thiobarbituric acid reactive substances, protein carbonyls, electric conductivity, and organoleptic deterioration in the trout fillets. Notably, the most effective treatment in this context was KCA + DEO + OA. The shelf-life of trout fillets was established through the assessment of multiple parameters. It was determined to be 4 days in both the control and KCA groups, 8 days in the OA and KCA + OA groups, 16 days in the KCA + DEO group, and a minimum of 20 days in the KCA + DEO + OA group. Consequently, our recommendation is to apply an active coating based on KCA, incorporating DEO in conjunction with OA packaging, for the preservation of fish fillets stored in refrigeration.