Modified Atmosphere Systems and Shelf Life Extension of Fish and Fishery Products

Extending the Shelf Life of Atlantic Salmon (Salmo salar) with Sub-Chilled Storage and Modified Atmosphere Packaging in Recyclable Mono-Material Trays

This study investigated the effect of sub-chilling whole gutted salmon and sub-chilled storage at -1 °C in modified-atmosphere packaging in two recyclable mono-material trays (CPET, HDPE). Quality parameters were measured, including water-holding properties, salt content, color, texture, lipid oxidation, and sensory and microbiological shelf life. The oxygen transmission rate was measured for the packages. Compared to traditional fish storage on ice, sub-chilling gave a 0.4% weight gain, better water-holding capacity, and higher salt content. The sub-chilled fish gave a significantly better sensory quality and microbiological shelf life of up to 49 days. Photobacterium was the dominating bacteria during storage. Salmon packaged in CPET trays had a higher drip loss than HDPE trays, but a lower rate of lipid oxidation (1-penten-3-ol). Our results showed the feasibility of significantly extending shelf life with sub-chilling, removing the need for ice. Moreover, using recyclable trays for packaging contributes to a circular economy without compromising food quality.

Effect of Vacuum and Modified Atmosphere Packaging on the Shelf Life and Quality of Gutted Rainbow Trout (Oncorhynchus mykiss) during Refrigerated Storage

The quality changes of gutted rainbow trout in vacuum packaging (VP) and modified atmosphere packaging (MAP) with 40% CO2 + 60% N2 (MAP1), 60% CO2 + 40% N2 (MAP2), and 90% CO2 + 10% N2 (MAP3) were evaluated. The samples were stored at 3 ± 0.5 °C, and on days 1, 4, 7, 10, 13, and 16 of storage, microbiological, chemical, and sensory testing was performed. The aerobic plate count (APC) and psychrotrophic bacteria count (PBC) in VP fish exceeded the conventional limit of 7 log cfu/g on day 10, and in MAP1 and MAP2 fish on day 16, whereas in MAP3 fish, their number remained below that limit during the experiment. MAP significantly slowed down the growth of Enterobacteriaceae in trout, and the degree of inhibition increased with increasing CO2 concentration in the gas mixture. The lowest lactic acid bacteria numbers were detected in VP fish, whereas the highest numbers were determined in trout packaged in MAP2 and MAP3. Significantly lower numbers of hydrogen sulfide-producing (H2S) bacteria were detected in fish packed in MAP. Distinct patterns were observed for pH among treatments. The lowest increase in TBARS values was detected in VP and MAP3 fish, whereas in MAP1 and MAP2 fish, the TBARS values were higher than 1 mg MDA/kg on day 16 of storage when a rancid odor was detected. MAP inhibited the increase in total volatile basic nitrogen (TVB-N) content of trout compared to trout packaged in a vacuum. The sensory attributes of trout perceived by the sensory panel changed significantly in all experimental groups during storage. Based primarily on sensory, but also microbial, and chemical parameters, MAP has great potential for preserving fish quality and extending the shelf life of gutted rainbow trout from 7 days in VP to 13 days in MAP1 and MAP2, and to 16 days in MAP3.

Analysis of Quality and Color Properties according to the Gas Composition (Modified Atmosphere Packaging) of Pork Sous-Vide Ham Preserved in Natural Brine

The purpose of this study was to analyze whether seawater has positive effects on appearance characteristics, such as CIE a*, and to determine the gas composition concentration that is suitable for maintaining it. Pork hind meat was cured with four types of curing agent for 5 d at 4°C. The different curing agents comprised the control salt, control nitrite pickling salt (CN), treatment brine, and treatment bittern (BT). The cured hams were cooked at 65°C for 4 h and packaged at O₂:N₂ gas ratios of 7:3, 8:2, and 9:1 for 3 wk. The physicochemical properties were assessed immediately after heating the sample, and the color properties were measured after a 3 wk storage period. Based on the correlation results of the physicochemical properties, BT had a higher curing and cooking yield than the other treatments, owing to its high salinity. Results of color properties for BT (7:3) and CN (8:2) showed similar color CIE L*, CIE a* chroma, and hue angle values. Therefore, BT can be said to be a sous-vide curing agent suitable for preserving the color of ham, and a high nitrogen concentration of 30% helps to maintain the appearance of seawater sous-vide ham.

Insights into electrospun pullulan-carboxymethyl chitosan/PEO core-shell nanofibers loaded with nanogels for food antibacterial packaging

Nisin, a natural substance from Lactococcus lactis, displays a promising antibacterial ability against the gram-positive bacteria. However, it is susceptible to the external environment, i.e. temperature, pH, and food composition. In this study, a dual stabilization method, coaxial electrospinning, was applied to protect nisin in food packaging materials and the effect of nisin concentration on the properties of the nanofibers was investigated. The core-shell nanofibers with pullulan as a core layer and carboxymethyl chitosan (CMCS)/polyethylene oxide (PEO) as shell layer were prepared, and then the prepared CMCS-nisin nanogels (CNNGs) using a self-assembly method were loaded into the core layer of the nanofibers as antibacterial agents. The result revealed that the smooth surface can be observed on the nanofibers by microstructure characterization. The CNNGs-loaded nanofibers exhibited enhanced thermal stability and mechanical strength, as well as excellent antibacterial activity. Importantly, the as-formed nanofibers were applied to preserve bass fish and found that the shelf life of bass fish packed by CNNGSs with nisin at a concentration of 8 mg/mL was effectively extended from 9 days to 15 days. Taken together, the CNNGs can be well stabilized with the core-shell nanofibers, thus exerting significantly improved antimicrobial stability and bioactivity. This special structure exerts a great potential for application as food packaging materials to preserve aquatic products.

Analysis of Water Distribution and Muscle Quality of Silver Carp (Hypophthalmichthys molitrix) Chunks Based on Electron-Beam Irradiation

Electron-beam irradiation (EBI) is an efficient, safe, and nonthermal sterilization technique that is extensively used in food preservation research. Here we report the effects of different EBI doses (0, 4, 8 kGy) and preservation temperatures (room temperature [RT], 4 °C) on the muscle water distribution and muscle quality indices of silver carp chunks (SCCs). The highest entrapped water content was found in the 4-kGy-irradiated/4-°C-stored samples. The expressible moisture content (EMC) of the SCCs increased with increasing irradiation dose and was significantly lower in the RT group than in the 4 °C group. The irradiation dose and preservation temperature had no significant effect on the moisture content, whiteness value and protein content of SCCs (p > 0.05). When the irradiation dose reached 8 kGy, AV value, POV value and TVB value were significantly increased (p < 0.05). The myofibrillar protein content and actomyosin content of the SCCs in the 4 °C group was higher than that of the specimens in the RT group by 0.29−0.98 mg/mL (p < 0.05) and 36.21−296.58 μg/mL (p < 0.05), respectively. Overall, EBI treatment (4 kGy) and low-temperature preservation (4 °C) helped retain the muscle water content of the SCCs and preserve their quality, thereby endorsing the EBI treatment of silver carp products.

Application of Fourier Transform Infrared (FT-IR) Spectroscopy, Multispectral Imaging (MSI) and Electronic Nose (E-Nose) for the Rapid Evaluation of the Microbiological Quality of Gilthead Sea Bream Fillets

The potential of Fourier transform infrared (FT-IR) spectroscopy, multispectral imaging (MSI), and electronic nose (E-nose) was explored in order to determine the microbiological quality of gilthead sea bream (Sparus aurata) fillets. Fish fillets were maintained at four temperatures (0, 4, 8, and 12 °C) under aerobic conditions and modified atmosphere packaging (MAP) (33% CO₂, 19% O₂, 48% N₂) for up to 330 and 773 h, respectively, for the determination of the population of total viable counts (TVC). In parallel, spectral data were acquired by means of FT-IR and MSI techniques, whereas the volatile profile of the samples was monitored using an E-nose. Thereafter, the collected data were correlated to microbiological counts to estimate the TVC during fish fillet storage. The obtained results demonstrated that the partial least squares regression (PLS-R) models developed on FT-IR data provided satisfactory performance in the estimation of TVC for both aerobic and MAP conditions, with coefficients of determination (R²) for calibration of 0.98 and 0.94, and root mean squared error of calibration (RMSE_C) values of 0.43 and 0.87 log CFU/g, respectively. However, the performance of the PLS-R models developed on MSI data was less accurate with R² values of 0.79 and 0.77, and RMSE_C values of 0.78 and 0.72 for aerobic and MAP storage, respectively. Finally, the least satisfactory performance was observed for the E-nose with the lowest R² (0.34 and 0.17) and the highest RMSE_C (1.77 and 1.43 log CFU/g) values for aerobic and MAP conditions, respectively. The results of this work confirm the effectiveness of FT-IR spectroscopy for the rapid evaluation of the microbiological quality of gilthead sea bream fillets.

Effects of Individual and Block Freezing on the Quality of Pacific Oyster (Crassostrea gigas) during Storage under Different Pretreatment Conditions

In this study, a series of pretreatments, including ice-glazing, polyphosphate impregnated, and both ice-glazing and polyphosphate impregnated, were employed to pretreat shucked oysters in order to explore the optimal processing conditions for long-time storage. The effect of repeated freezing-thawing cycles on the quality of oysters was evaluated. Several quality indicators were used to investigate the effects of pretreatment. For the VBN (volatile salt-based nitrogen) value, the lowest value was 9.1 ± 0.2 of BPG (block oyster with polyphosphate impregnated and ice-glazing), which was significantly lower than 9.6 ± 0.2 of IPG (individual oyster with polyphosphate impregnated and ice-glazing). In terms of drip loss, there was no significant difference between the IPG (21.0 ± 0.2%) and the BPG (20.8 ± 0.2%). In addition, the highest WHC% (water holding capacity) was IPG (65.5 ± 0.5%) which was slightly lower than BPG (67.6 ± 0.6%). As compared to the experimental control, the IPG and BPG had the best appearance and color. In terms of TAPC (total aerobic plate count), with the increase of freezing storage time, each group showed a slight downward trend, but the difference was not statistically significant. After repeated freezing-thawing of block frozen oysters, there were significant differences in drip loss, WHC, and cooked taste with the increasing number of times, and there was a trend of deterioration (p < 0.05). Repeated freezing and thawing can seriously degrade the quality of oysters, so individual freezing (especially IPG) should be the most appropriate processing method.

Polyolefin Innovations toward Circularity and Sustainable Alternatives

The unprecedented growth and socioeconomic impacts of polyolefins clearly outline a major success story in the world of polymer science. Polyolefins revolutionizes industries such as health care, construction, and food packaging. Despite the benefits of polyolefins, there is a rising concern for the environment due to high production volume (i.e., fossil fuel consumption), often short usage time, and problems related to waste management and accumulation in the natural environment. Creating a circular economy for polyolefins through effective recycling technologies has the potential to decrease the environmental impact of these materials. This perspective discusses polyolefins and their impact, existing and emerging recycling/upcycling solutions, and recycle-by-design alternatives that are challenging the status quo.

Active and Intelligent Packaging for Enhancing Modified Atmospheres and Monitoring Quality and Shelf Life of Packed Gilthead Seabream Fillets at Isothermal and Variable Temperature Conditions

The study investigated the effect of active modified atmosphere packaging (20% CO2–60% N2–20% O2) with CO2 emitters (MAP-PAD) and conventional MAP (MAP) on the quality and shelf-life of gilthead seabream fillets during chill storage, while the most appropriate enzymatic Time Temperature Integrators (TTI) were selected for monitoring their shelf-life at isothermal and variable temperature storage conditions (Teff = 4.8 °C). The concentration of CO2 and O2 in the headspace of the package, volatile compounds and of the microbial population were monitored during storage. The kinetic parameters for bacterial growth were estimated at 0–10 °C using the Baranyi growth model. The MAP-PAD samples presented significantly lower microbial growth rates and longer lag phases compared to the MAP samples, leading to significant shelf-life extension: 2 days of extension at 2.5 °C and 5 °C, while 50% extension at variable conditions (Teff = 4.8 °C). CO2 emitters in the package improved the chemical freshness (K-values) and volatile compounds (characterizing freshness). The responses of different enzymatic TTI were modeled as the function of enzyme concentration, temperature and storage time. The activation energy (Ea) ranged from 97 to 148 kJ mol−1, allowing the selection of appropriate TTIs for the shelf-life monitoring of each fish product: LP-150U for the MAP and M-25U for the MAP-PAD samples. The validation experiment at Teff = 4.8 °C confirmed the applicability of Arrhenius-type models, as well as the use of TTIs as effective chill chain management tools during distribution and storage.

Application of Biotechnology in Specific Spoilage Organisms of Aquatic Products

Aquatic products are delicious and have high nutritive value, however, they are highly perishable during storage due to the growth and metabolism of microorganisms. The spoilage process of aquatic products was demonstrated to be highly related to the composition of microorganisms, in which the specific spoilage organisms (SSOs) are the main factors. In this article, the spoilage indicators of SSOs were systematically described, which could make a comprehensive evaluation of the quality of aquatic products. Quorum sensing (QS) regulates the growth, metabolism and characteristics of SSOs, the common signaling molecules and the QS system in the major SSOs of aquatic products were discussed. Moreover, we compared various technologies for the analysis of SSOs in aquatic products. Besides, quality control techniques based on microbiota regulating of aquatic products, including physical, chemical and biological preservation strategies, were also compared. In conclusion, novel preservation technologies and hurdle techniques are expected to achieve comprehensive inhibition of SSOs.

Effect of edible coating and modified atmosphere packaging on the microbiological and physicochemical stability of retail maki sushi

The effect of pH, packaging atmosphere (100% air, 40%, or 70% CO₂ balanced with N₂ ), and an edible chitosan coating was tested on the retail maki Sushi's microbiological and physiochemical stability. In two experiments, maki sushi was studied using sushi rice with an initial pH of 4.2 ± 0.05 and 4.8 ± 0.05. In the first experiment (lower pH), no apparent effect of neither modified atmosphere packaging (MAP) nor coating on bacterial growth was observed. However, raising the pH showed an apparent effect of low-CO₂ MAP and chitosan coating (p < 0.05). Both MAP and coating partly affected the maki sushi cross-section's visual perception, but no significant adverse effects were observed. An important observation was the improved stability of the pink salmon color in chitosan-coated maki sushi stored in low-CO₂ MAP compared to other groups. It is concluded that storage of Maki sushi at 4°C gives acceptable microbial stability and appropriate quality. However, an edible chitosan coating, especially in combination with low-CO₂ MAP, increases the microbiological stability and preserves the colorimetric properties of maki sushi stored at 8°C. Notably, this combination could work as a safety measure against temperature abuse in the food cold chain. PRACTICAL APPLICATION: Using an edible coating with active packaging can improve retail maki sushi's temperature tolerance and preserve its colorimetric properties. It is a fast and cost-effective technology with a substantial industrial potential easy to implement.

Mild processing of seafood-A review

Recent years have shown a tremendous increase in consumer demands for healthy, natural, high-quality convenience foods, especially within the fish and seafood sector. Traditional processing technologies such as drying or extensive heating can cause deterioration of nutrients and sensory quality uncompilable with these demands. This has led to development of many novel processing technologies, which include several mild technologies. The present review highlights the potential of mild thermal, and nonthermal physical, and chemical technologies, either used alone or in combination, to obtain safe seafood products with good shelf life and preference among consumers. Moreover, applications and limitations are discussed to provide a clear view of the potential for future development and applications. Some of the reviewed technologies, or combinations thereof, have shown great potential for non-seafood products, yet data are missing for fish and seafood in general. The present paper visualizes these knowledge gaps and the potential for new technology developments in the seafood sector. Among identified gaps, the combination of mild heating (e.g., sous vide or microwave) with more novel technologies such as pulsed electric field, pulsed light, soluble gas stabilization, cold plasma, or Ohmic heat must be highlighted. However, before industrial applications are available, more research is needed.

Freeze-Chilling of Whitefish: Effects of Capture, On-Board Processing, Freezing, Frozen Storage, Thawing, and Subsequent Chilled Storage-A Review

The current review investigates how whitefish quality is affected by capture at sea, on board handling, freezing, double freezing, frozen storage, thawing, and chilled storage. Packaging of fillets in MAP and vacuum are also covered. The main goal was to evaluate the freeze-chilling concept as a possible method for the fishing industry for all-year-round marketing of fish captured during the relatively short fishing period. The review covers both the effect of each processing step in the supply chain as well as the combined effect of all steps in the chain from sea to consumer, including post-thawing chilled storage, defined as the freeze-chilling method.

Recent Developments in Seafood Packaging Technologies

Seafood products are highly perishable, owing to their high water activity, close to neutral pH, and high content of unsaturated lipids and non-protein nitrogenous compounds. Thus, such products require immediate processing and/or packaging to retain their safety and quality. At the same time, consumers prefer fresh, minimally processed seafood products that maintain their initial quality properties. The present article aims to review the literature over the past decade on: (i) innovative, individual packaging technologies applied to extend the shelf life of fish and fishery products, (ii) the most common combinations of the above technologies applied as multiple hurdles to maximize the shelf life of seafood products, and (iii) the respective food packaging legislation. Packaging technologies covered include: Modified atmosphere packaging; vacuum packaging; vacuum skin packaging; active food packaging, including oxygen scavengers; carbon dioxide emitters; moisture regulators; antioxidant and antimicrobial packaging; intelligent packaging, including freshness indicators; time–temperature indicators and leakage indicators; retort pouch processing and edible films; coatings/biodegradable packaging, used individually or in combination for maximum preservation potential.

A Long-Term Stable Sensor Based on Fe@PCN-224 for Rapid and Quantitative Detection of H2O2 in Fishery Products

Hydrogen peroxide (H2O2) has been reported to be used for the illegal treatment of fishery products in order to obtain "fake" freshness. Residues of H2O2 in food may be of toxicology concern. In this study, a nonenzymatic sensor was developed based on Fe@PCN-224 metal-organic frameworks wrapped by Nafion to detect H2O2 concentration. The hybrid structure of Fe@PCN-224 was fabricated by incorporated free FeIII ions into the center of PCN-224, which was ultra-stable due to the strong interactions between Zr6 and the carboxyl group. Scanning electron spectroscopy images exhibited that Nafion sheets crossed together on the surface of Fe@PCN-224 nanoparticles to form a hierarchical and coherent structure for efficient electron transfer. Electrochemical investigations showed that the Fe@PCN-224/Nafion/GCE possessed good linearity from 2 to 13,000 μM (including four orders of magnitude), low detection limits (0.7 μM), high stability in continuous monitoring (current remained nearly stable over 2300 s) and in long-term measurement (current decreased 3.4% for 30 days). The prepared nanohybrid modified electrode was effectively applied to H2O2 detection in three different fishery products. The results were comparable to those measured using photometrical methods. The developed electrochemical method has a great potential in detecting the illegal management of fishery products with H2O2.

The microbial safety of fish and fish products: Recent advances in understanding its significance, contamination sources, and control strategies

Microorganisms play a crucial and unique role in fish and fish product safety. The presence of human pathogens and the formation of histamine caused by spoilage bacteria make the control of both pathogenic and spoilage microorganisms critical for fish product safety. To provide a comprehensive and updated overview of the involvement of microorganisms in fish and fish product safety, this paper reviewed outbreak and recall surveillance data obtained from government agencies from 1998 to 2018 and identified major safety concerns associated with both domestic and imported fish products. The review also summarized all available literature about the prevalence of major and emerging microbial safety concerns, including Salmonella spp., Listeria monocytogenes, and Aeromonas hydrophila, in different fish and fish products and the survival of these pathogens under different storage conditions. The prevalence of antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARGs), two emerging food safety concerns, is also reviewed. Pathogenic and spoilage microorganisms as well as ARB and ARGs can be introduced into fish and fish products in both preharvest and postharvest stages. Many novel intervention strategies have been proposed and tested for the control of different microorganisms on fish and fish products. One key question that needs to be considered when developing and implementing novel control measures is how to ensure that the measures are cost and environment friendly as well as sustainable. Over the years, regulations have been established to provide guidance documents for good farming and processing practices. To be more prepared for the globalization of the food chain, harmonization of regulations is still needed.

Evaluation of IoT-Enabled Monitoring and Electronic Nose Spoilage Detection for Salmon Freshness During Cold Storage

Salmon is a highly perishable food due to temperature, pH, odor, and texture changes during cold storage. Intelligent monitoring and spoilage rapid detection are effective approaches to improve freshness. The aim of this work was an evaluation of IoT-enabled monitoring system (IoTMS) and electronic nose spoilage detection for quality parameters changes and freshness under cold storage conditions. The salmon samples were analyzed and divided into three groups in an incubator set at 0 °C, 4 °C, and 6 °C. The quality parameters, i.e., texture, color, sensory, and pH changes, were measured and evaluated at different temperatures after 0, 3, 6, 9, 12, and 14 days of cold storage. The principal component analysis (PCA) algorithm can be used to cluster electronic nose information. Furthermore, a Convolutional Neural Networks and Support Vector Machine (CNN-SVM) based algorithm is used to cluster the freshness level of salmon samples stored in a specific storage condition. In the tested samples, the results show that the training dataset of freshness is about 95.6%, and the accuracy rate of the test dataset is 93.8%. For the training dataset of corruption, the accuracy rate is about 91.4%, and the accuracy rate of the test dataset is 90.5%. The overall accuracy rate is more than 90%. This work could help to reduce quality loss during salmon cold storage.

Sous-Vide as a Technique for Preparing Healthy and High-Quality Vegetable and Seafood Products

Sous-vide is a technique of cooking foods in vacuum bags under strictly controlled temperature, offering improved taste, texture and nutritional values along with extended shelf life as compared to the traditional cooking methods. In addition to other constituents, vegetables and seafood represent important sources of phytochemicals. Thus, by applying sous-vide technology, preservation of such foods can be prolonged with almost full retention of native quality. In this way, sous-vide processing meets customers' growing demand for the production of safer and healthier foods. Considering the industrial points of view, sous-vide technology has proven to be an adequate substitute for traditional cooking methods. Therefore, its application in various aspects of food production has been increasingly researched. Although sous-vide cooking of meats and vegetables is well explored, the challenges remain with seafoods due to the large differences in structure and quality of marine organisms. Cephalopods (e.g., squid, octopus, etc.) are of particular interest, as the changes of their muscular physical structure during processing have to be carefully considered. Based on all the above, this study summarizes the literature review on the recent sous-vide application on vegetable and seafood products in view of production of high-quality and safe foodstuffs.

100th Anniversary of Macromolecular Science Viewpoint: Needs for Plastics Packaging Circularity

Plastic packaging has gained an increasing amount of attention in all aspects of society. Over the past several decades, plastics became the material of choice due to their excellent properties, performance, and economics, but the end of life of plastics is not well managed. This has led to plastic waste in our environment, especially the oceans, rivers, and estuaries, driving legislative, industrial, and voluntary initiatives to make the necessary pivot to circularity. While the plastics recycling industry has made many advances in its relatively short life, there are still many technical and societal hurdles to be overcome. The goal of this work is not to provide a complete review of recycling as it pertains to circularity, but rather to highlight the technical gaps that need to be collaboratively addressed by the entire plastics community to achieve circularity. Each stage along the path, from design of packaging and materials of construction to sortation, recycling, and reprocessing are ripe for innovation. The most relevant issues are introduced to provide a starting point for research across all fields of polymer science to aid in reducing the environmental impact of plastic packaging waste.

Effectiveness of Sodium Alginate Active Coatings Containing Bacteriocin EFL4 for the Quality Improvement of Ready-to-Eat Fresh Salmon Fillets during Cold Storage

This study developed a biopreservation method for ready-to-eat (RTE) fresh salmon fillets based on the use of bacteriocin EFL4 produced by bacteriocinogenic Enterococcus faecalis L04 previously isolated from Chinese sea bass (Lateolabrax maculatus). Bacteriocin EFL4 has the ability to inhibit the growth of several fish-spoilage bacteria and foodborne pathogens, including Staphylococcus aureus, Escherichia coli, Shewanella putrefaciens, Pseudomonas fluorescens and Listeria monocytogenes, and the minimal inhibitory concentration (MIC) for S. putrefaciens was 0.32 μg/mL. The biopreservation potential of bacteriocin EFL4 for RTE fresh salmon fillets during cold storage at 4 °C was tested for the first time on a laboratory scale. Microbiological and physicochemical properties, as well as organoleptic evaluations, have been done during the biopreservation trials. The results show that RTE fresh salmon fillets treated with 0.64 μg/mL bacteriocin EFL4 could significantly (p < 0.05) reduce the total viable count (TVC), total volatile basic nitrogen (TVB-N), K value and maintain the quality of RTE fresh salmon fillets during 8-day storage on the basis of the organoleptic evaluation results.

Volatilome of Chill-Stored European Seabass (Dicentrarchus labrax) Fillets and Atlantic Salmon (Salmo salar) Slices under Modified Atmosphere Packaging

Fish spoilage occurs due to production of metabolites during storage, from bacterial action and chemical reactions, which leads to sensory rejection. Investigating the volatilome profile can reveal the potential spoilage markers. The evolution of volatile organic molecules during storage of European seabass (Dicentrarchus labrax) fillets and Atlantic salmon (Salmo salar) slices under modified atmosphere packaging at 2 °C was recorded by solid-phase microextraction combined with gas chromatography-mass spectrometry. Total volatile basic nitrogen (TVB-N), microbiological, and sensory changes were also monitored. The shelf life of seabass fillets and salmon slices was 10.5 days. Pseudomonas and H₂S-producing bacteria were the dominant microorganisms in both fish. TVB-N increased from the middle of storage, but never reached concentrations higher than the regulatory limit of 30–35 mg N/100 g. The volatilome consisted of a number of aldehydes, ketones, alcohols and esters, common to both fish species. However, different evolution patterns were observed, indicating the effect of fish substrate on microbial growth and eventually the generation of volatiles. The compounds 3-hydroxy-2-butanone, 2,3-butanediol, 2,3-butanedione and acetic acid could be proposed as potential spoilage markers. The identification and quantification of the volatilities of specific fish species via the development of a database with the fingerprint of fish species stored under certain storage conditions can help towards rapid spoilage assessment.

Preservative Effects of Gelatin Active Coating Containing Eugenol and Higher CO2 Concentration Modified Atmosphere Packaging on Chinese Sea bass (Lateolabrax maculatus) during Superchilling (-0.9 °C) Storage

The purpose of this research was to explore the fresh keeping effect of modified atmosphere packaging (MAP) with different gas ratios combined with gelatin active coatings containing eugenol on Chinese sea bass stored at −0.9 °C for 36 days. The results showed that MAP3 (60% CO₂/10% O₂/30% N₂), together with gelatin active coatings containing eugenol, could prevent water loss, which maintained high field NMR, MRI, and organoleptic evaluation results. This hurdle technology could also effectively delay the bacterial reproduction, protein degradation, and alkaline accumulation, so it showed the lowest K value, total volatile basic nitrogen, free amino acids, total viable count, Pseudomonas spp., and H₂S-producing bacteria, which better maintain the quality of sea bass.

Modeling the Effect of Active Modified Atmosphere Packaging on the Microbial Stability and Shelf Life of Gutted Sea Bass

The aim of the study was the evaluation and mathematical modeling of the effect of active modified atmosphere packaging (MAP), by the incorporation of CO2 emitters in the package, on the microbial stability and shelf life of gutted sea bass during refrigerated storage. Gutted sea bass samples were packaged in modified atmosphere (50% CO2–40% N2–10% O2) with and without CO2 emitters (ACT-MAP, MAP) (gas/product volume ratio 3:1) and stored at isothermal conditions: 0 °C, 5 °C, and 10 °C. The gas concentration in the package headspace (%CO2, %O2) and microbial growth (total viable count, TVC, Pseudomonas spp., Enterobacteriaceae spp., lactic acid bacteria) were monitored during storage. The microbial growth was modeled using the Baranyi growth model, and the kinetic parameters (microbial growth rate, lag phase) were estimated at the tested temperature and packaging conditions. The results showed that the ACT-MAP samples presented significantly lower microbial growth compared to the MAP samples. The growth rate of the total viable count at 0 °C was 0.175 and 0.138 d−1 for the MAP and ACT-MAP sea bass, respectively (p < 0.05). The shelf life of the MAP sea bass at 0–10 °C (based on a final TVC value: 7 log CFU g−1) was extended 4–7 days with the addition of a CO2 emitter in the package. The CO2 concentration in the ACT-MAP samples was stabilized at approximately 60%, while the CO2 in the MAP samples was approximately 40% at the end of the shelf life.

Natural Preservatives for Extending the Shelf-Life of Seafood: A Revisit

Consumer demand for minimally processed seafood that retains its sensory and nutritional properties after handling and storage is increasing. Nevertheless, quality loss in seafood occurs immediately after death, during processing and storage, and is associated with enzymatic, microbiological, and chemical reactions. To maintain the quality, several synthetic additives (preservatives) are promising for preventing the changes in texture and color, development of unpleasant flavor and rancid odor, and loss of nutrients of seafood during storage at low temperature. However, the use of these preservatives has been linked to potential health hazards. In this regard, natural preservatives with excellent antioxidant and antimicrobial properties have been extensively searched and implemented as safe alternatives in seafood processing, with the sole purpose of extending shelf-life. Natural preservatives commonly used include plants extracts, chitosan and chitooligosaccharide, bacteriocins, bioactive peptides, and essential oils, among others. This review provides updated information about the production, mode of action, applications, and limitations of these natural preservatives in seafood preservation.

A Comparison of the Effects of Packaging Containing Nano ZnO or Polylysine on the Microbial Purity and Texture of Cod (Gadus morhua) Fillets

Portions of fresh Baltic cod fillets were packed into cellulose boxes (control samples), which were covered with Methyl Hydroxypropyl Celluloses (MHPC) coating with 2% polylysine. The cellulose boxes had square PE films and were enclosed in MHPC coating containing ZnO nanoparticles. The cod fillets were stored at 5 °C and examined after 72 h and 144 h storage times. Results obtained in this study showed that the textural parameters of the cod fillets increased, with both Springiness and Cohesiveness found greater after 144 h of storage for all analysed packaging materials. The Gumminess of fillets increased after storage, but the lowest increase was noted in cod samples that were stored in boxes containing PE films with ZnO nanoparticles. It was found that water loss from the cod fillets in these boxes was also lowest. The Adhesiveness of the fish samples stored in boxes devoid of active coatings also increased. In contrast to the packaging material devoid of active coatings, the storage of fillets in active coating boxes resulted in a decrease of adhesiveness. Microbial analysis showed that packaging material containing nano-ZnO was found to be more active against mesophilic and psychotropic bacterial cells than the coatings with polylysine after 72 h and 144 h of storage.

Seafood Processing and Safety

Food microorganisms are found on all surfaces (skin and gills) and in the intestines of fishery products.[...].