Effect of low voltage electrostatic field combined with partial freezing on the quality and microbial community of large yellow croaker

Mechanism of low-voltage electrostatic field on flavor retention in refrigerated sturgeon caviar: Insights from phospholipids

This study investigated the effect of low-voltage electrostatic field on the flavor quality changes and generation pathways of refrigerated sturgeon caviar. Research has found that after storage for 3-6 weeks, the physicochemical properties of caviar in the LVEF treatment group are better than those in the control group. The results of two-dimensional gas chromatography-time-of-flight mass spectrometry showed that the contents of hexanal, nonanal, (E,Z)-2,6-nonadienal, (E)-2-octenal and 1-octene-3-one related to the characteristic flavor of caviar (sweet, fruity and green) increased significantly. The lipidomics results indicated that the effects of LVEF on caviar mainly involve glycerophospholipid metabolism, linoleic acid metabolism, and α-Linolenic acid metabolism. Methanophosphatidylcholine (15:0/18:1), phosphatidylcholine (18:0/20:5), and phosphatidylcholine (18,1e/22:6) were significantly correlated with odor formation. Therefore, low-voltage electrostatic field treatment preserved the quality and enhanced the flavor of sturgeon caviar. This study provided a new theoretical basis for the preservation of sturgeon caviar.

Effect of konjac glucomannan-based preservation pads on quality changes in refrigerated large yellow croaker (Pseudosciaena crocea)

The purpose of this study was to evaluate the preservation effects of konjac glucomannan (KGM)/oregano essential oil (OEO) Pickering emulsion-based pads (K/OPE pads) on large yellow croaker (Pseudosciaena crocea) fillets stored at 4 °C. The K/OPE pads were fabricated using a freeze-drying technique. The homogeneous distribution of the OEO Pickering emulsions in the KGM matrix was observed using scanning electron microscopy. Fourier transform infrared spectroscopy confirmed that the OEO emulsions were encapsulated in the KGM and there was hydrogen bonding interaction between them. Compared with the KGM pads, the K/OPE pad groups demonstrated enhanced antioxidant and antimicrobial properties. When the content of OPE was increased from 20 % to 40 %, the antioxidant performance of the K/OPE pads increased from 48.09 % ± 0.03 % to 86.65 % ± 0.02 % and the inhibition range of Escherichia coli and Staphylococcus aureus increased to 13.84 ± 0.81 and 16.87 ± 1.53 mm, respectively. At the same time, K/OPE pads were more effective in inhibiting the formation of total volatile alkaline nitrogen and the production of thiobarbituric acid-reactive substances, thereby helping in reducing water loss and maintaining the muscle tissue structure of fish fillets for a longer storage time. Consequently, these K/OPE40 pads extended the shelf life of the fish fillets by an additional 4 days and delayed spoilage during refrigerated storage. The findings suggest that the K/OPE pads can effectively safeguard the quality of refrigerated large yellow croaker fillets, presenting their potential as an active packaging material in the fish preservation industry.

Comprehensive insights into the organoleptic characteristics attributes of "HuangYuXiang": Integration of volatilomics, sensomics, macrogenomics, lipidomics, and metabolomics

HuangYuXiang (HYX) is a colorful and flavorful traditional cuisine in China, which development of organoleptic attributes is a complex process. Flavor sensory attributes was explored through volatilomics, sensomics, macrogenomics, lipidomics, and metabolomics in seven HYXs. Group B demonstrated the highest sensory scores. A total of 41 volatiles were detected, of which 7 were identified as key volatiles. Caulobacteraceae sp., Psychrobacter faecalis, Ralstonia pickettii, Carnobacterium divergens, and Psychrobacter cibarius were representative bacteria in HYXs. A total of 679 lipids (251 differential lipids) and 329 (113 differential metabolites) metabolites were identified. The differential compounds were the main contributors to flavor differences. L-homocitrulline, arg-ser, 4-aminobenzoic acid, arg-gly, sucrose, pyridoxine, D-cyclohexylglycine, PC 21:4/22:6, PC O-15:0/22:5, PC O-20:2/20:5, and FA 18:2 were heavily accumulated under the microbial action, which in turn promoted the formation of aroma and taste substances. The results of this study provide a theoretical basis for the standardized processing of high-quality HYX.

Growth Reduction of Vibrionaceae and Microflora Diversity in Ice-Stored Pacific White Shrimp (Penaeus vannamei) Treated with a Low-Frequency Electric Field

A novel storage technique that combines the low-frequency electric field (LFEF) and ice temperature was used to extend the shelf life of Pacific white shrimp (Penaeus vannamei). The study investigated the effect of LFEF treatment on the quality and microbial composition of Penaeus vannamei during storage at ice temperature. The results showed that the LFEF treatment significantly extended the shelf life of shrimp during storage at ice temperature. The total volatile base nitrogen (TVB-N) and pH of samples increased over time, while the total viable count (TVC) showed a trend of first decreasing and then increasing. Obviously, shrimp samples treated with LFEF had a lower pH, TVB-N and TVC values than the untreated samples (p < 0.05) at the middle and late stages of storage. LFEF treatment increased the diversity and altered the composition of the microbial communities in Penaeus vannamei. Additionally, the treatment led to a decrease in the relative abundance of dominant spoilage bacteria, including Aliivibrio, Photobacterium and Moritella, in Penaeus vannamei stored at ice temperature for 11 days. Furthermore, correlation analysis indicated that TVB-N and pH had a significant and positive correlation with Pseudoalteromonas, suggesting that Pseudoalteromonas had a greater impact on shrimp quality. This study supports the practical application of accelerated low-frequency electric field-assisted shrimp preservation as an effective means of maintaining shrimp meat quality.

Changes in the physicochemical characteristics and microbial community compositions of the abdomen and cheliped muscles in swimming crab (Portunus trituberculatus) during frozen storage

The physicochemical indexes and microbial diversity were investigated to compare the altered quality properties of the abdomen and cheliped muscle in swimming crab (Portunus trituberculatus) during 100 days of frozen storage at -20℃. Over the extended duration of frozen storage, the sensory evaluation, moisture content, water activity (Aw), and water-holding capacity (WHC) in the abdomen and cheliped muscles of swimming crab decreased, while the pH, total volatile basic nitrogen (TVB-N), and trimethylamine (TMA) increased. The increase and decrease rates of these indicators were smaller in the abdomen than those in the cheliped muscle. High-throughput sequencing results indicated a reduction in the microbial richness and diversity in the abdomen and cheliped muscles of the swimming crab as frozen storage time extended. Proteobacteria, Actinobacteriota, and Firmicutes, Achromobacter, Kocuria, and Staphylococcus were the dominant phylum and genus in both muscle tissues, respectively. Furthermore, the correlation analysis between the composition of the microbiota and physiochemical properties revealed that the growths of Kocuria, Vibrio, Staphylococcus, and Aliiroseovarius were closely related to the physiochemical factors. The study provides a theoretical reference for quality deterioration and develops new products of different parts in the swimming crab during frozen storage.

Effect of low-voltage electrostatic field-assisted partial freezing on large yellow croaker protein properties and metabolomic analysis during storage

BACKGROUND

Large yellow croaker is highly perishable during storage because of high protein and moisture content. The degradation of the fish is mainly attributed to microbial growth and enzyme activity, so it is important to find an efficient storage method to extend its shelf life.

METHODOLOGY

This study investigated the effect of a low-voltage electrostatic field combined with partial freezing treatment on the physicochemical properties of myofibrillar protein (MP) and metabolomic analysis of large yellow croaker during preservation. The samples in chilled storage (C), partial freezing storage (PF) and 6 kV/m low-voltage electrostatic field partial freezing storage (LVEF-PF) were analyzed during an 18 day storage period.

RESULTS

In comparison with the C and PF groups, LVEF-PF delayed the oxidation of MP by inhibiting the formation of carbonyl groups (2.25 nmol/mg pro), and maintaining higher sulfhydryl content (29.73 nmol/mg pro). Fourier transform infrared (FTIR) spectroscopy and fluorescence spectroscopy analysis also demonstrated that the LVEF-PF treatment maintained the stability of the protein structure by increasing the a-helix ratio (19.88%) and reducing the random coil ratio (17.83%). Scanning electron microscopy showed that, compared with the LVEF-PF group, there was more degeneration and aggregation of MP in the C and PF groups after 18 days' storage. The results of untargeted metabolomic analysis showed that 415 kinds of differential metabolites were identified after storage, and the difference levels of differential metabolites were least between the samples treated with LVEF-PF stored on the ninth day and the fresh samples. The main differential metabolic pathways during storage were amino acid metabolism and lipid metabolism.

CONCLUSION

The LVEF-PF treatment could maintain the stability of myofibrillar protein in large yellow croaker during storage. These results showed a potential application of the LVEF-PF method for aquatic product preservation. © 2023 Society of Chemical Industry.

Effect of Intertidal Vegetation (Suaeda salsa) Restoration on Microbial Diversity in the Offshore Areas of the Yellow River Delta

The coastal wetlands in the Yellow River Delta play a vital role in the ecological function of the area. However, the impact of primary restoration on microbial communities is not yet fully understood. Hence, this study aimed to analyze the bacterial and archaeal communities in the soil. The results indicated that Marinobacter and Halomonas were predominant in the bacterial community during spring and winter. On the other hand, Muribaculaceae and Helicobacter were prevalent during the core remediation of soil, while Inhella and Halanaerobium were predominant in non-vegetation-covered high-salinity soil. The bacterial Shannon index showed significant differences in vegetation-covered areas. For archaea, Salinigranum, Halorubrum, and Halogranum were dominant in vegetation areas, while Halolamina, Halogranum, and Halorubrum were prevalent in non-vegetation areas. The colonization of Suaeda salsa led to differences in the composition of bacteria (22.6%) and archaea (29.5%), and salt was one of the significant reasons for this difference. The microflora was more diverse, and the elements circulated after vegetation grounding, while the microbial composition in non-vegetation areas was similar, but there was potential competition. Therefore, vegetation restoration can effectively restore soil ecological function, while the microorganisms in the soil before restoration provide germplasm resources for pollutant degradation and antimicrobial development.

Emerging technologies in seafood processing: An overview of innovations reshaping the aquatic food industry

Seafood processing has traditionally been challenging due to the rapid spoilage rates and quality degradation of these products. With the rise of food science and technology, novel methods are being developed to overcome these challenges and improve seafood quality, shelf life, and safety. These methods range from high-pressure processing (HPP) to edible coatings, and their exploration and application in seafood processing are of great importance. This review synthesizes the recent advancements in various emerging technologies used in the seafood industry and critically evaluates their efficacy, challenges, and potential benefits. The technologies covered include HPP, ultrasound, pulsed electric field, plasma technologies, pulsed light, low-voltage electrostatic field, ozone, vacuum cooking, purified condensed smoke, microwave heating, and edible coating. Each technology offers unique advantages and presents specific challenges; however, their successful application largely depends on the nature of the seafood product and the desired result. HPP and microwave heating show exceptional promise in terms of quality retention and shelf-life extension. Edible coatings present a multifunctional approach, offering preservation and the potential enhancement of nutritional value. The strength, weakness, opportunity, and threat (SWOT) analysis indicates that, despite the potential of these technologies, cost-effectiveness, scalability, regulatory considerations, and consumer acceptance remain crucial issues. As the seafood industry stands on the cusp of a technological revolution, understanding these nuances becomes imperative for sustainable growth. Future research should focus on technological refinements, understanding consumer perspectives, and developing regulatory frameworks to facilitate the adoption of these technologies in the seafood industry.

Dynamic Changes in the Microbial Composition and Spoilage Characteristics of Refrigerated Large Yellow Croaker (Larimichthys crocea) during Storage

The quality changes, dynamic changes in microbial composition, and diversity changes in large yellow croaker (Larimichthys crocea) during 4 °C refrigeration were studied using 16S rDNA high-throughput sequencing technology, and the total viable count (TVC), total volatile basic nitrogen (TVB-N), and thiobarbituric acid-reactive substances (TBARS) were determined. The results revealed a consistent increase in TVC, TVB-N, and TBARS levels over time. On the 9th day, TVC reached 7.43 lg/(CFU/g), while on the 15th day, TVB-N exceeded the upper limit for acceptable quality, reaching 42.56 mg/100 g. Based on the 16S rDNA sequencing results, we categorized the storage period into three phases: early storage (0th and 3rd days), middle storage (6th day), and late storage (9th, 12th, and 15th days). As the storage time increased, both the species richness and diversity exhibited a declining trend. The dominant genus identified among the spoilage bacteria in refrigerated large yellow croaker was Pseudomonas, accounting for a high relative abundance of 82.33%. A comparison was carried out of the spoilage-causing ability of three strains of Pseudomonas screened and isolated from the fish at the end of storage, and they were ranked as follows, from strongest to weakest: P. fluorescen, P. lundensis, and P. psychrophila. This study will provide a theoretical basis for extending the shelf life of large yellow croaker.

Cryoprotective Effect of NADES on Frozen-Thawed Mirror Carp Surimi in Terms of Oxidative Denaturation, Structural Properties, and Thermal Stability of Myofibrillar Proteins

Quality degradation due to the formation and growth of ice crystals caused by temperature fluctuations during storage, transportation, or retailing is a common problem in frozen surimi. While commercial antifreeze is used as an ingredient in frozen surimi, its high sweetness does not meet the contemporary consumer demand for low sugar and low calories. Therefore, the development of new green antifreeze agents to achieve an enhanced frozen-thawed stability of surimi has received more attention. The aim of this study was to develop a cryoprotectant (a mixture of citric acid and trehalose) to enhance the frozen-thawed stability of surimi by inhibiting the oxidative denaturation and structural changes of frozen-thawed mirror carp (Cyprinus carpio L.) surimi myofibrillar protein (MP). The results showed that the amounts of free amine, sulfhydryl, α-helix, intrinsic fluorescence intensity, and thermal stability in the control significantly decreased after five F-T cycles, while the Schiff base fluorescence intensity, amounts of disulfide bonds and surface hydrophobicity significantly increased (p < 0.05). Compared to sucrose + sorbitol (SS), the natural deep eutectic solvents (NADES) effectively inhibited protein oxidation. After five F-T cycles, the α-helix content and Ca2+-ATPase activity of the NADES samples were 4.32% and 80.0%, respectively, higher, and the carbonyl content was 17.4% lower than those of the control. These observations indicate that NADES could inhibit oxidative denaturation and enhance the structural stability of MP.

Cryoprotective effect of water-tailored trehalose-based natural deep eutectic solvents on frozen-thawed mirror carp (Cyprinus carpio L.) surimi

The inhibitory effect of water-tailored natural deep eutectic solvents (NADES) constructed from citric acid and trehalose with different amounts on the quality deterioration and oxidation of frozen-thawed (F-T) mirror carp (Cyprinus carpio L.) surimi was studied. NADES was obtained by citric acid to trehalose and the effect of moisture addition (v/v) on the structure, physicochemical, and anti-freezing capacity of NADES was assessed. NADES + 10 % H₂O has relatively low viscosity (25 %) and strong freezing resistance. However, a 50 % H₂O addition leads to the disappearance of the hydrogen bond. The addition of NADES effectively inhibits water loss, migration, and mechanical damage on F-T surimi. An inhibitory effect of 4 % (w/w) NADES on oxidation was verified by a decrease in carbonyl contents (17.4 %, 8.63 %) and TBARS (37.9 %, 15.2 %) of surimi compared with control (P < 0.05) and sucrose + sorbitol after 5F-T cycles, suggesting the potential of NADES as a cryoprotectant for the food industry.