Microbial and physicochemical evolution during hyperbaric storage at room temperature of fresh Atlantic salmon (Salmo salar)

Evaluation of Lipid Oxidation Characteristics in Salmon after Simulation of Cold Chain Interruption Using Rapid Evaporation Ionization Mass Spectrometry

Temperature fluctuations occurring during the cold chain logistics of salmon contribute to lipid oxidation. This study aimed to simulate cold chain interruption through freeze-thaw operations and evaluate the lipidomics data from salmon samples subjected to different numbers of freeze-thaw cycles by using rapid evaporative ionization mass spectrometry (REIMS) combined with an intelligent surgical knife (iKnife). The results indicated significant differences in the relative abundance of characteristic ions among the samples (p < 0.05). A total of 34 ions with variable importance for the projection values ≥1 were identified as potential biomarkers, including m/z 719.4233 ([PCC36:5-NH(CH3)3]-), m/z 337.3134 ([FAC22:1]-), m/z 720.4666 ([PEC35:6-H]-), m/z 309.2780 ([FAC20:1]-), m/z 777.4985 ([PCC40:4-NH(CH3)3]-), m/z 745.4421 ([PCC38:6-NH(CH3)3]-/[PEC38:6-NH3]-), m/z 747.4665 ([PCC38:5-NH(CH3)3]-/[PEC38:5-NH3]-), etc. The degree of lipid oxidation was found to be associated with the number of freeze-thaw cycles, exhibiting the most significant alterations in the relative abundance of lipid ions in the 8T samples. Additionally, sensory evaluation by the CIE-L*a*b* method and volatile analysis by headspace solid-phase microextraction gas chromatography-mass spectrometry demonstrated significant differences (p < 0.05) in color and odor among the salmon samples, with a correlation to the number of freeze-thaw cycles. The primary compounds responsible for alterations in salmon odor were aldehydes with lower odor thresholds. In summary, the iKnife-REIMS method accurately differentiated salmon muscle tissues based on varying levels of lipid oxidation, thus expanding the application of REIMS.

Advancements in nonthermal physical field technologies for prefabricated aquatic food: A comprehensive review

Aquatic foods are nutritious, enjoyable, and highly favored by consumers. In recent years, young consumers have shown a preference for prefabricated food due to its convenience, nutritional value, safety, and increasing market share. However, aquatic foods are prone to microbial spoilage due to their high moisture content, protein content, and unsaturated fatty acids. Furthermore, traditional processing methods of aquatic foods can lead to issues such as protein denaturation, lipid peroxidation, and other food safety and nutritional health problems. Therefore, there is a growing interest in exploring new technologies that can achieve a balance between antimicrobial efficiency and food quality. This review examines the mechanisms of cold plasma, high-pressure processing, photodynamic inactivation, pulsed electric field treatment, and ultraviolet irradiation. It also summarizes the research progress in nonthermal physical field technologies and their application combined with other technologies in prefabricated aquatic food. Additionally, the review discusses the current trends and developments in the field of prefabricated aquatic foods. The aim of this paper is to provide a theoretical basis for the development of new technologies and their implementation in the industrial production of prefabricated aquatic food.

Improving fresh cheese shelf-life through hyperbaric storage at variable room temperature

The changes in microbiological, physiochemical, and textural properties in fresh cheeses made from either cow or goat milk were observed under hyperbaric storage (HS, 50-100 MPa) at room temperature (RT) and compared with refrigerated storage under normal atmospheric pressure for 60 days. An initial microbial growth inhibition was observed for both cheese types, as well as a considerable inactivation of all endogenous microbiota under HS/RT (75-100 MPa/RT). This contributed to a higher stability of pH and color values, especially at the higher pressure at room temperature (100 MPa/RT) throughout 60 days storage. A compression effect occurred during HS/RT, resulting in higher whey loss, reduction in moisture content, and textural changes. Such changes tended to decrease over time, to values closer to the initial ones, with hardness values at the 60th day of storage at 75/RT similar to those observed for refrigeration on the 7th day and 1.4-fold higher than those observed at 100/RT. Overall, HS/RT reduced the microbial populations load during storage (≥5 log units in some cases), with minimal effects on most of the evaluated quality parameters. These results point to a considerable shelf-life extension of HS fresh cheeses, without temperature control, pinpointing HS as a more sustainable preservation strategy than refrigeration, with great potential for industrial application. PRACTICAL APPLICATION: The results presented in this study point to increased microbial stability of fresh cheeses when stored under hyperbaric storage without temperature control, leading possibly to an increased shelf-life, of up to 60 days. This kind of new food preservation strategy may be suitable for longer transportation of foods, where energy may not be handily and widely available, while additionally contributing to increased shelf-life and safety. Also, hyperbaric storage could be applied throughout the food storage, improving shelf-life with a lower carbon footprint than refrigeration.

Effects of immersing treatment of curcumin and piperine combined with vacuum packaging on the quality of salmon (Salmo salar) during cold chain logistics

In order to study the effects of the compound preservatives (curcumin and piperine (CP)) and vacuum packaging (VP) on the quality of salmon during cold chain logistics suffered from temperature abuse, the physiochemical indexes (texture, water holding capacity (WHC), total volatile basic nitrogen (TVB-N), thiobarbituric acid reactive substances (TBARS), free amino acids (FAA) contents), microbial indicators (total mesophilic bacteria count (MBC), total psychrotrophic bacteria count (PBC), H2S-producing bacteria count (HSBC)) were determined, and the moisture changes were explored by near-infrared (NIR) spectroscopy and low-field nuclear magnetic resonance (LF-NMR). The results showed that the treatment of curcumin and piperine in combination with vacuum packaging could maintain the quality of salmon suffered from temperature abuse most effectively. At the end of storage, the MBC of VP+CP was only 4.95 log CFU/g, which was about 1 log CFU/g lower than the control sample stored at the same condition. The combined treatment also retarded the increase of TVB-N, TBARS, and the decrease of hardness, springiness, and a* value, as well as water migration in salmon, contributing to higher water holding capacity and better appearance. Besides, VP+CP retarded the decrease of free glutamate, which contributed to umami taste. Due to the biological activity and safety of the preserves, the combined treatment could be a promising method for preservation of seafood.

Preservation of high pressure pasteurised milk by hyperbaric storage at room temperature versus refrigeration on inoculated microorganisms, fatty acids, volatile compounds and lipid oxidation

High pressure pasteurised (HPP) milk was stored by hyperbaric storage at room temperature (HS/RT) (50-100 MPa at 20 °C) and compared with refrigeration (RF), to assess the effect on two pathogens surrogates and a pathogenic, up to 120 days, and on fatty acids, volatile organic compounds (VOCs) and secondary lipid oxidation over 60 days. HS/RT (75-100 MPa) was able to inactivate at least 6.68/6.31/6.03 log CFU/mL of Escherichia coli/Listeria innocua/Salmonella Senftenberg (to below the detection limit), while RF resulted only in minor changes. Overall, fatty acids profile remained stable under HS/RT, although secondary lipid oxidation showed slightly higher values. In addition, both HS/RT and RF showed stable and similar VOCs profiles and off-flavour indicative compounds were not detected, except for the lowest pressure (50 MPa) after 40 days. HS/RT preserved HPP milk with enhanced microbial safety, shelf-life and quality compared to RF, being in addition quasi-energetically costless and more sustainable than RF.

Effects of Chitosan-Grafted-Phenolic Acid Coating on Quality and Microbiota Composition of Vacuum-Packaged Sea Bass (Lateolabrax japonicus) Fillets during Chilled Storage

ABSTRACT

The aim of this research was to experimentally assess the effect of chitosan (CS)-grafted phenolic acid (CS-g-PA) derivatives on the quality and microbiota composition of vacuum-packaged sea bass (Lateolabrax japonicus). Samples were treated by deionized water (CK), 1% CS, 1% CS-g-PA copolymer, and 1% CS-grafted gallic acid (CS-g-GA) copolymer for 10 min and combined with vacuum packaging stored at 4°C to analyze the microbiological and physicochemical indicators; they were also combined with 16s RNA high-throughput sequencing to explore the effects of CS derivatives on quality and microbial composition. The results showed that the treatment of CS-g-GA and CS-g-PA could retard the increase of pH, total volatile basic nitrogen, and the K value. The degradation of ATP-related compounds, production of biogenic amines, and growth of spoilage bacteria were inhibited by CS-g-GA and CS-g-PA. Moreover, CS-g-GA and CS-g-PA performed better in the inhibition of lipid oxidation by the analysis of thiobarbituric acid reactive substances and relative fluorescence intensity. According to the results of high-throughput sequencing, the diversity of microbial composition in all groups was decreased significantly during chilled storage, especially in the CK group. The predominant microorganism was Acinetobacter in the middle period of storage, while Pseudomonas and Shewanella became predominant at the end of storage. The treatment of CS-g-GA and CS-g-PA had significant effects inhibiting the growth of Shewanella during storage. On the basis of the analysis of the microorganism and physicochemical quality, compared with the CK group, CS-g-GA and CS-g-PA can maintain the good quality of sea bass fillets and prolong the shelf life for another 12 days.

HIGHLIGHTS

Analysis of Alternative Shelf Life-Extending Protocols and Their Effect on the Preservation of Seafood Products

Seafood is essential to a healthy and varied diet due to its highly nutritious characteristics. However, seafood products are highly perishable, which results in financial losses and quality concerns for consumers and the industry. Due to changes in consumer concerns, demand for healthy products has increased. New trends focusing on reducing synthetic preservatives require innovation and the application of additional or alternative strategies to extend the shelf life of this type of product. Currently, refrigeration and freezing storage are the most common methods for fish preservation. However, refrigeration alone cannot provide long shelf-life periods for fish, and freezing worsens sensorial characteristics and consumer interest. Therefore, the need to preserve seafood for long periods without exposing it to freezing temperatures exists. This review focuses on the application of other approaches to seafood products, such as biodegradable films and coating technology; superchilling; irradiation; high-pressure processing; hyperbaric storage; and biopreservation with lactic acid bacteria, bacteriocins, or bacteriophages. The efficiency of these techniques is discussed based on their impact on microbiological quality, sensorial degradation, and overall preservation of the product’s nutritional properties. Although these techniques are already known, their use in the industrial processing of seafood is not widespread. Thus, the novelty of this review is the aggregation of recent studies on shelf life extension approaches, which provide useful information for the selection of the most appropriate technology and procedures and industrial innovation. Despite the fact that all techniques inhibit or delay bacterial proliferation and product decay, an undesirable sensory impact may occur depending on the treatment conditions. Although no technique appears to replace refrigeration, the implementation of additional treatments in the seafood processing operation could reduce the need for freezing, extending the shelf life of fresh unfrozen products.

Inhibition of Several Bacterial Species Isolated from Squid and Shrimp Skewers by Different Natural Edible Compounds

Seafood is an excellent source of nutrients, essential for a healthy diet, ranging from proteins and fatty acids to vitamins and minerals. Seafood products are highly perishable foods due to their nutritional characteristics and composition. The application of nontoxic, natural, and edible preservatives to extend the shelf-life and inhibit bacterial proliferation of several foods has been a hot topic. Consequently, this work aimed to perform the microbiological characterization of squid and shrimp skewers during their shelf-life (five days) and evaluate the susceptibility of randomly isolated microorganisms to several natural edible compounds so that their application for the preservation and shelf-life extension of the product might be analyzed in the future. The product had considerably high total microorganisms loads of about 5 log CFU/g at day zero and 9 log CFU/g at day five. In addition, high bacterial counts of Pseudomonas spp., Enterobacterales, and lactic acid bacteria (LAB) were found, especially on the last day of storage, being Pseudomonas the dominant genus. However, no Escherichia coli or Listeria monocytogenes were detected on the analyzed samples. One hundred bacterial isolates were randomly selected and identified through 16s rRNA sequencing, resulting in the detection of several Enterobacterales, Pseudomonas spp., and LAB. The antibacterial activity of carvacrol, olive leaf extract, limonene, Citrox®, different chitosans, and ethanolic propolis extracts was evaluated by the agar diffusion method, and the minimum inhibitory concentration was determined only for Citrox® since only this solution could inhibit all the identified isolates. At concentrations higher than or equal to 1.69% (v/v), Citrox® demonstrated bacteriostatic and bactericidal activity to 97% and 3% of the isolates, respectively. To our knowledge, there are no available data about the effectiveness of this commercial product on seafood isolates. Although preliminary, this study showed evidence that Citrox® has the potential to be used as a natural preservative in these seafood products, improving food safety and quality while reducing waste. However, further studies are required, such as developing a Citrox®-based coating and its application on this matrix to validate its antimicrobial effect.

Fingerprint Approaches Coupled with Chemometrics to Discriminate Geographic Origin of Imported Salmon in China's Consumer Market

Of the salmon sold in China’s consumer market, 92% was labelled as Norwegian salmon, but was in fact was mainly imported from Chile. The aim of this study was to establish an effective method for discriminating the geographic origin of imported salmon using two fingerprint approaches, Near-infrared (NIR) spectroscopy and mineral element fingerprint (MEF). In total, 80 salmon (40 from Norway and 40 from Chile) were tested, and data generated by NIR and MEF were analysed via various chemometrics. Four spectral preprocessing methods, including vector normalization (VN), Savitzky Golay (SG) smoothing, first derivative (FD) and second derivative (SD), were employed on the raw NIR data, and a partial least squares (PLS) model based on the FD + SG9 pretreatment could successfully differentiate Norwegian salmons from Chilean salmons, with a R² value of 98.5%. Analysis of variance (ANOVA) and multiple comparative analysis were employed on the contents of 16 mineral elements including Pb, Fe, Cu, Zn, Al, Sr, Ni, As, Cr, V, Se, Mn, K, Ca, Na and Mg. The results showed that Fe, Zn, Al, Ni, As, Cr, V, Se, Ca and Na could be used as characteristic elements to discriminate the geographical origin of the imported salmon, and the discrimination rate of the linear discriminant analysis (LDA) model, trained on the above 10 elements, could reach up to 98.8%. The results demonstrate that both NIR and MEF could be effective tools for the rapid discrimination of geographic origin of imported salmon in China’s consumer market.

Fresh Fish Degradation and Advances in Preservation Using Physical Emerging Technologies

Fresh fish is a highly perishable food characterized by a short shelf-life, and for this reason, it must be properly handled and stored to slow down its deterioration and to ensure microbial safety and marketable shelf-life. Modern consumers seek fresh-like, minimally processed foods due to the raising concerns regarding the use of preservatives in foods, as is the case of fresh fish. Given this, emergent preservation techniques are being evaluated as a complement or even replacement of conventional preservation methodologies, to assure food safety and extend shelf-life without compromising food safety. This paper reviews the main mechanisms responsible for fish spoilage and the use of conventional physical methodologies to preserve fresh fish, encompassing the main effects of each methodology on microbiological and chemical quality aspects of this highly perishable food. In this sense, conventional storage procedures (refrigeration and freezing) are counterpointed with more recent cold-based storage methodologies, namely chilling and superchilling. In addition, the use of novel food packaging methodologies (edible films and coatings) is also presented and discussed, along with a new storage methodology, hyperbaric storage, that states storage pressure control to hurdle microbial development and slow down organoleptic decay at subzero, refrigeration, and room temperatures.

Enhanced preservation of vacuum-packaged Atlantic salmon by hyperbaric storage at room temperature versus refrigeration

Hyperbaric storage at room temperature (HS/RT: 75 MPa/25 °C) of vacuum-packaged fresh Atlantic salmon (Salmo salar) loins was studied for 30 days and compared to atmospheric pressure at refrigerated temperatures (AP/5 °C, 30 days) and RT (AP/25 °C, 5 days). Most of the fatty acids were not affected by storage conditions, with only a slight decrease of docosahexaenoic acid (DHA) content (n-3 polyunsaturated fatty acid) for AP samples, reflected in the lower polyene index values obtained and higher oxidation extent. For HS, a lower lipid oxidation extension and a slower increase of myofibrillar fragmentation index values were observed, when compared to AP samples. The volatile profile was similar for the HS and fresh samples, with the HS samples retaining fresh-like alcohols and aldehydes components, which disappeared in AP samples, mainly in AP/25 °C samples. The volatile profile for AP samples (5 and 25 °C) revealed mostly spoilage-like compounds due to microbial activity. Drip loss increased progressively during the 30 days of storage under HS, while a slight decrease of water holding capacity after 5 days was observed, increasing further after 30 days. Regarding textural properties, only resilience was affected by HS, decreasing after 30 days. So, HS/RT could represent an interesting extended preservation methodology of fresh salmon loins, since allows retaining important physicochemical properties for at least 15 days, while refrigeration after 5 days showed already volatile spoilage-like compounds due to microbial activity. Furthermore, this methodology allows additional considerable energy savings when compared to refrigeration.

Effect of Cold Chain Logistic Interruptions on Lipid Oxidation and Volatile Organic Compounds of Salmon (Salmo salar) and Their Correlations With Water Dynamics

Lipid oxidation and water migration are important factors in the quality changes of aquatic products. This study investigated the relationship between water migration and lipid oxidation in salmon filets under four different storage conditions (control: 0°C; T1: 4°C; T2 and T3: two temperature fluctuation groups) by detecting thiobarbituric acid–reactive substances, changes of fatty acids, and volatile organic compounds (VOCs), and other quality indicators including redness, microorganism, total volatile basic nitrogen (TVB-N), and water-holding capacity (WHC) were also measured. The results of low-field nuclear magnetic resonance (LF-NMR) showed that more trapped water (T₂₂) turned to form free water (T₂₃) in groups suffering temperature fluctuations. A more significant decrease in fatty acids was found in T2 and T1 groups, especially oleic acid (C18:1n9c), linoleic acid (C18:2n6c), and palmitic acid (C16:0). The VOCs with off-flavors (1-penten-3-ol, 2-penten-1-ol, (Z)-, 1-octen-3-ol, hexanal) in the groups suffered from simulated cold chain interruptions increased faster than the other two groups during storage. T₂₂ was negatively correlated (p < 0.05) with stearic acid (C18:0), 1-penten-3-ol, hexanal, and nonanal, whereas T₂₃ was positively correlated with 1-penten-3-ol, hexanal, and heptanal. Therefore, the temperature fluctuation accelerated the loss of polyunsaturated fatty acids and the increase of unpleasant odors related to water migration.

Hyperbaric storage at room like temperatures as a possible alternative to refrigeration: evolution and recent advances

From 2012, the preservation of food products under pressure has been increasingly studied and the knowledge acquired has enlarged since several food products have been studied at different storage conditions. This new food preservation methodology concept called Hyperbaric Storage (HS) has gain relevance due to its potential as a replacement or an improvement to the conventional cold storage processes, such as the traditional refrigeration (RF), or even frosting, from the energetic savings to the reduction of the carbon foot-print. Briefly, HS is capable to inhibit the microbial proliferation or its inactivation which results in the extension of the shelf-life of several food products when compared to RF. Moreover, the overall quality parameters seem not to be affected by HS, being the differences detected on samples over storage similar to lower when compared to the ones stored at RF. This review paper aims to gather data from all studies carried out so far regarding HS performance, mainly at room temperature on fruit juices, meat and fisheries, as well on dairy products and ready-to-eat meals. The HS advantages as a new food preservation methodology are presented and explained, being also discussed the industrial viability and environmental impact of this methodology, as well its limitations.

Improvement of the refrigerated preservation technology by hyperbaric storage for raw fresh meat

BACKGROUND

This work aimed to compare raw fresh meat (minced bovine and pork in pieces) preserved by hyperbaric storage (HS) at room-like temperature (75 MPa/25 °C) and HS at cold temperatures (60 MPa/10 °C) for up to 60 days, being both compared to refrigeration (RF, 4 °C).

RESULTS

HS conditions showed microbial load reductions over 60 days of storage, leading to a possible shelf-life extension when compared to samples at RF. Moreover, between both HS conditions similar results were found at the 60^th day, reaching in some cases values < 1.00 log CFU g^-1 . Overall, pH presented an increase with storage for both HS conditions (e.g. over 30 days, from 5.51 ± 0.02 to 5.70 ± 0.01 and 5.85 ± 0.03, for 60 MPa/10 °C and 75 MPa/25 °C, respectively, on pork meat in pieces, PP) contrary to RF where pH values decreased (from 5.51 ± 0.02 to 5.33 ± 0.03). Regarding moisture content and drip loss, lower and higher values were found, respectively at 75 MPa/25 °C, mainly in bovine minced meat. Overall, colour ΔE* did not present considerable differences for both samples under all storage conditions. Lipid oxidation presented an increase tendency over time, with both HS conditions showing the higher values (1.795 ± 0.217 and 2.169 ± 0.117 for 60 MPa/10 °C and 75 MPa/25 °C, respectively, compared to 0.895 ± 0.084 μg MDA g^-1 in PP samples at the 30^th day).

CONCLUSION

Although several advantages were found further studies should be carried out in order to optimize the HS conditions for raw fresh meat and assess the impact of this preservation methodology on other meat quality parameters as for instance sensorial aspects. © 2019 Society of Chemical Industry.

Applying Fourier Transform Mid Infrared Spectroscopy to Detect the Adulteration of Salmo salar with Oncorhynchus mykiss

The aim of this study was to evaluate the potential of Fourier transform infrared (FTIR) spectroscopy coupled with chemometric methods to detect fish adulteration. Muscles of Atlantic salmon (Salmo salar) (SS) and Salmon trout (Onconrhynchus mykiss) (OM) muscles were mixed in different percentages and transformed into mini-burgers. These were stored at 3 °C, then examined at 0, 72, 160, and 240 h for deteriorative microorganisms. Mini-burgers was submitted to Soxhlet extraction, following which lipid extracts were analyzed by FTIR. The principal component analysis (PCA) described the studied adulteration using four principal components with an explained variance of 95.60%. PCA showed that the absorbance in the spectral region from 721, 1097, 1370, 1464, 1655, 2805, to 2935, 3009 cm⁻¹ may be attributed to biochemical fingerprints related to differences between SS and OM. The partial least squares regression (PLS-R) predicted the presence/absence of adulteration in fish samples of an external set with high accuracy. The proposed methods have the advantage of allowing quick measurements, despite the storage time of the adulterated fish. FTIR combined with chemometrics showed that a methodology to identify the adulteration of SS with OM can be established, even when stored for different periods of time.