In situ investigation of ice fractions and water states during partial freezing of pork loins and shrimps.

Ice fractions and water states in partially frozen muscle foods greatly affect their quality. In the study, a variable temperature nuclear magnetic resonance (VT-NMR) with a liquid nitrogen temperature control system was employed to in situ investigate the relationship between ice fractions and temperatures and changes in water states during partial freezing and thawing of pork and shrimp. Results indicated that changes in ice fractions ranging from -2 âˆ¼ -20 °C could be divided into 3 stages including slow increase, random leap and remarkable leap. More serious damages to the structures related to immobile water occurred in shrimp than in pork, and partial freezing also caused deterioration in muscle fibres related to free water. Additionally, -2 âˆ¼ -3 °C and - 3.5 °C were the appropriate partial freezing temperatures for pork and shrimp, respectively. Therefore, the VT-NMR method possessed great potential for fundamental studies and applications of partial freezing of muscle foods.

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.

Zebrafish as a high throughput model for organ preservation and transplantation research.

Despite decades of effort, the preservation of complex organs for transplantation remains a significant barrier that exacerbates the organ shortage crisis. Progress in organ preservation research is significantly hindered by suboptimal research tools that force investigators to sacrifice translatability over throughput. For instance, simple model systems, such as single cell monolayers or co-cultures, lack native tissue structure and functional assessment, while mammalian whole organs are complex systems with confounding variables not compatible with high-throughput experimentation. In response, diverse fields and industries have bridged this experimental gap through the development of rich and robust resources for the use of zebrafish as a model organism. Through this study, we aim to demonstrate the value zebrafish pose for the fields of solid organ preservation and transplantation, especially with respect to experimental transplantation efforts. A wide array of methods were customized and validated for preservation-specific experimentation utilizing zebrafish, including the development of assays at multiple developmental stages (larvae and adult), methods for loading and unloading preservation agents, and the development of viability scores to quantify functional outcomes. Using this platform, the largest and most comprehensive screen of cryoprotectant agents (CPAs) was performed to determine their toxicity and efficiency at preserving complex organ systems using a high subzero approach called partial freezing (i.e., storage in the frozen state at -10°C). As a result, adult zebrafish cardiac function was successfully preserved after 5 days of partial freezing storage. In combination, the methods and techniques developed have the potential to drive and accelerate research in the fields of solid organ preservation and transplantation.

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

The effect of low voltage electrostatic field combined with partial freezing (LVEF- PF) treatment on storage quality and microbial community of large yellow croaker was studied. Three different methods including chilled (C), partial freezing (PF) and 6 kV/m electrostatic field combined partial freezing storage were used to preserve large yellow croaker for 18 days. Total viable counts (TVC), sensory evaluation, and physiochemical index including pH, total volatile basic nitrogen (TVB-N), K value and centrifugal loss were examined. During storage, the large yellow croaker was susceptible to microbial growth and spoilage. However, LVEF-PF treatment was found to be effective in enhancing sensory quality, inhibiting microbial growth, and maintaining myofibril microstructure. Low field nuclear magnetic resonance showed that LVEF-PF treatment reduced the migration of immobilized water to free water. At 18th day, the TVC value of LVEF-PF, PF and chilled group were 3.56 log CFU/g, 5.11 log CFU/g, 7.73 log CFU/g, respectively. Therefore, from the results of TVB-N and TVC value, the shelf life of LVEF-PF group was at least 3 days longer than PF group, and 6 days longer than the chilled group. High-throughput sequencing showed that the microbial community diversity significantly decreased during storage. The predominant bacteria in chilled, PF, LVEF-PF group at 18th day were Pseudomonas, Psychrobacter and Shewanella, respectively, and the relative abundance of spoilage bacteria such as Pseudomonas and Psychrobacter were reduced by LVEF-PF treatment, that corresponding with lower values of TVB-N and TVC value. LVEF-PF treatment could be used as a new processing and storage method to delay deterioration and prolong shelf life of large yellow croaker.

Monitoring of freezing patterns within 3D collagen-hydroxyapatite scaffolds using infrared thermography.

The importance of cryopreservation in tissue engineering is unceasingly increasing. Preparation, cryopreservation, and storage of tissue-engineered constructs (TECs) at an on-site location offer a convenient way for their clinical application and commercialization. Partial freezing initiated at high sub-zero temperatures using ice-nucleating agents (INAs) has recently been applied in organ cryopreservation. It is anticipated that this freezing technique may be efficient for the preservation of both scaffold mechanical properties and cell viability of TECs. Infrared thermography is an instrumental method to monitor INAs-mediated freezing of various biological entities. In this paper, porous collagen-hydroxyapatite (collagen-HAP) scaffolds were fabricated and characterized as model TECs, whereas infrared thermography was proposed as a method for monitoring the crystallization-related events on their partial freezing down to -25 °C. Intra- and interscaffold latent heat transmission were descriptively evaluated. Nucleation, freezing points as well as the degree of supercooling and duration of crystallization were calculated based on inspection of respective thermographic curves. Special consideration was given to the cryoprotective agent (CPA) composition (Snomax®, crude leaf homogenate (CLH) from Hippophae rhamnoides, dimethyl sulfoxide (Me2SO) and recombinant type-III antifreeze protein (AFP)) and freezing conditions ('in air' or 'in bulk CPA'). For CPAs without ice nucleation activity, thermographic measurements demonstrated that the supercooling was significantly milder in the case of scaffolds present in a CPA solution compared to that without them. This parameter (ΔT, °C) altered with the following tendency: 10 Me2SO (2.90 ± 0.54 ('scaffold in a bulk CPA') vs. 7.71 ± 0.43 ('bulk CPA', P < 0.0001)) and recombinant type-III AFP, 0.5 mg/ml (2.65 ± 0.59 ('scaffold in a bulk CPA') vs. 7.68 ± 0.34 ('bulk CPA', P < 0.0001)). At the same time, in CPA solutions with ice nucleation activity the least degree of supercooling and the longest crystallization duration (Δt, min) for scaffolds frozen 'in air' were documented for CLH from Hippophae rhamnoides (1.57 ± 0.37 °C and 21.86 ± 2.93 min) compared to Snomax, 5 µg/ml (2.14 ± 0.33 °C and 19.91 ± 4.72 min), respectively). Moreover, when frozen 'in air' in CLH from Hippophae rhamnoides, collagen-HAP scaffolds were shown to have the longest ice-liquid equilibrium phase during crystallization and the lowest degree of supercooling followed by alginate core-shell capsules and nanofibrous electrospun fiber mats made of poly ɛ-caprolactone (PCL) and polylactic acid (PLA) (PCL/PLA) blend. The paper offers evidence that infrared thermography provides insightful information for monitoring partial freezing events in TECs when using different freezing containers, CPAs and conditions. This may further TEC-specific cryopreservation with enhanced batch homogeneity and optimization of CPA compositions of natural origin active at warm sub-zero temperatures.

Effect of water change on quality deterioration of Pacific white shrimp (Litopenaeus vannamei) during partial freezing storage.

The correlation between water changes and quality deterioration of Litopenaeus vannamei during partial freezing storage was evaluated in this study. Significant increases in cross-sectional area and equivalent diameter are detected, but the roundness and longiness of the ice crystals show irregular growth. Within the extension of storage, the bound water (T2b) and immobilized water (T21) decreased significantly. However, the free water (T22) increased significantly. Quality determination showed significant decrease in total sulfhydryl and Ca2+-ATPase, but significant increase in disulfide bonds during storage. Correlation analysis revealed that cross-sectional area showed significant negative correlation with total sulfhydryl and Ca2+-ATPase, while significant positive correlation with disulfide bonds, respectively. The correlation between water distribution index and Ca2+-ATPase, disulfide bonds was significant, respectively. Predicted models for the growth of ice crystals with respect to cross-sectional area and equivalent diameter size have been developed with the help of the Arrhenius model.

Effect of three culture patterns on quality changes of crayfish meats during partial freezing storage.

The quality changes and main metabolites of rice-crayfish (DT), intensive crayfish (JY), and lotus pond crayfish (OT) under three culture patterns during partial freezing were studied. Compared with the DT and JY groups, the OT samples had higher thiobarbituric acid reactive substances (TBARS), K values and color values. The microstructure of the OT samples deteriorated most obviously during storage, and they had the lowest water-holding capacity and the worst texture. Furthermore, differential metabolites of crayfish under different culture patterns were identified by UHPLC-MS, and the most abundant differential metabolites of the OT groups were found. The main differential metabolites include alcohols polyols and carbonyl compounds; amines; amino acids, peptides, and analogues; carbohydrates and carbohydrate conjugates; fatty acids and conjugates. In conclusion, based on the analysis of existing data, the OT groups were considered to be the most serious deterioration during partial freezing compared with the other two culture patterns.

Quality changes and indicator proteins of Litopenaeus vannamei based on label-free proteomics analysis during partial freezing storage.

Litopenaeus vannamei are known to deteriorate in quality during low-temperature storage. This study demonstrated the potential protein indicators of partial freezing of stored shrimp by traditional quality parameters and label-free based proteomic techniques. The carbonyl content and myofibril fragmentation index (MFI) of shrimp increased from 0.56 ± 0.03 to 2.14 ± 0.03 nmol/mg and 13.09 ± 0.14 to 54.93 ± 0.96, respectively. Within the extension of storage, the trichloroacetic acid (TCA), cooking loss and whiteness significantly increased. A total of 240 proteins changed in abundance at 10, 20, and 30 days compared to fresh samples. Projectin, ribosomal protein and histone were potential biomarkers for protein denaturation and oxidation in shrimp muscle. Myosin heavy chain and glyceraldehyde-3-phosphate dehydrogenase corresponded with the degradation of muscle proteins. Myosin light chain, tubulin alpha chain, and heat shock protein correlated with tenderness and water holding capacity; meantime, malate dehydrogenase and hemocyanin can serve as color indicators. Further study of the properties of these indicator proteins can inform their exploitation as quality indicator proteins during partial freezing storage.

Current practice and novel approaches in organ preservation.

Organ transplantation remains the only treatment option for patients with end-stage organ failure. The last decade has seen a flurry of activity in improving organ preservation technologies, which promise to increase utilization in a dramatic fashion. They also bring the promise of extending the preservation duration significantly, which opens the doors to sharing organs across local and international boundaries and transforms the field. In this work, we review the recent literature on machine perfusion of livers across various protocols in development and clinical use, in the context of extending the preservation duration. We then review the next generation of technologies that have the potential to further extend the limits and open the door to banking organs, including supercooling, partial freezing, and nanowarming, and outline the opportunities arising in the field for researchers in the short and long term.

The effects of polyphenols on fresh quality and the mechanism of partial freezing of tilapia fillets.

BACKGROUND: Fish is one of the most popular foods for consumers because of its abundant nutrition, tenderness and delicious taste. With increasing demand for tilapia fillets, practical preservation is widely used to maintain quality and safety during long-distance transportation and storage. Thus the effects of polyphenols (2 g L-1 ) on color, flavor quality and mechanism of tilapia fillets were studied during 49 days of partial freezing (-4 °C). RESULTS: Treatment with carnosic acid (CA), procyanidin (PA), quercetin (QE) and resveratrol (RSV) inhibited water migration, myoglobin oxidation and psychrophilic bacteria stability during partial freezing storage. Aeromonas and Acinetobacter were the dominant bacteria of tilapia fillets during -4 °C storage. The relative abundance of aromatic substances (T70/2) in the polyphenol groups (>20%) was richer than in the control (CON) group (17%). Partial least squares discriminant analysis results showed that the different odors of the control and polyphenol groups were completely separated. Moreover, 35 fatty acids were identified by gas chromatographic analysis. On 49 days, the ratios of unsaturated fatty acids in the PA group (58.64%), QE group (57.70%) and RSV group (57.25%) were higher than in the control group (57.19%), and the PA group was the highest. CONCLUSION: Polyphenol treatment effectively maintained freshness and improved the quality of tilapia fillets during partial freezing. The polyphenol treatment comprehensively sustained the color and flavor quality of tilapia fillets found in the proposed mechanism. In particular, PA treatment was considered a potential method for preserving the freshness of fillets. © 2022 Society of Chemical Industry.

Quality changes and deterioration mechanisms in three parts (belly, dorsal and tail muscle) of tilapia fillets during partial freezing storage.

The quality changes in tilapia belly muscle (BM), dorsal muscle (DM) and tail muscle (TM) were studied and the hypothesis of browning of the fillets was revealed during partial freezing. Compared with DM and TM groups, BM samples had higher thiobarbituric acid reactive substances (TBARS) (0.41 mg malondialdehyde eq/kg at 49 d) and K values (61.81% at 42 d) (P < 0.05). The microstructure of the BM group deteriorated most obviously during storage. Therefore, the BM group was considered to be the fastest to oxidize and deteriorate. In addition, 54 different micromolecular metabolites were identified from tilapia fillets by UHPLC-Q-TOF-MS analysis, and there were significant differences in the micromolecular metabolites in the three parts of tilapia. Therefore, proteins and lipids were degraded by the action of enzymes and microorganisms to produce some amines and small molecular acids, leading to the deterioration of the quality of tilapia fillets.

The role of antifreeze glycoprotein (AFGP) and polyvinyl alcohol/polyglycerol (X/Z-1000) as ice modulators during partial freezing of rat livers.

Introduction: The current liver organ shortage has pushed the field of transplantation to develop new methods to prolong the preservation time of livers from the current clinical standard of static cold storage. Our approach, termed partial freezing, aims to induce a thermodynamically stable frozen state at high subzero storage temperatures (-10°C to -15°C), while simultaneously maintaining a sufficient unfrozen fraction to limit ice-mediated injury. Methods and results: Using glycerol as the main permeating cryoprotectant agent, this research first demonstrated that partially frozen rat livers showed similar outcomes after thawing from either -10°C or -15°C with respect to subnormothermic machine perfusion metrics. Next, we assessed the effect of adding ice modulators, including antifreeze glycoprotein (AFGP) or a polyvinyl alcohol/polyglycerol combination (X/Z-1000), on the viability and structural integrity of partially frozen rat livers compared to glycerol-only control livers. Results showed that AFGP livers had high levels of ATP and the least edema but suffered from significant endothelial cell damage. X/Z-1000 livers had the highest levels of ATP and energy charge (EC) but also demonstrated endothelial damage and post-thaw edema. Glycerol-only control livers exhibited the least DNA damage on Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining but also had the lowest levels of ATP and EC. Discussion: Further research is necessary to optimize the ideal ice modulator cocktail for our partial-freezing protocol. Modifications to cryoprotective agent (CPA) combinations, including testing additional ice modulators, can help improve the viability of these partially frozen organs.

Relationship between Micromolecules and Quality Changes of Tilapia Fillets after Partial Freezing Treatment with Polyphenols.

The study investigated the main characteristic micromolecular changes in tilapia fillets after partial freezing treatment with polyphenols by ultrahigh-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) analysis. A total of 2121 metabolite ion features were identified. The result suggested that procyanidin treatment increased the sweet, salty, and thick peptides' contents and suppressed the formation of bitter peptides. The levels of cis-4-octenedioic acid, 2-amino-heptanoic acid, indoleacrylic acid, and 2-amino-3-methyl-1-butanol in polyphenol treatments were significantly lower compared to those in the control group (P < 0.05), which delayed the formation of micromolecule of acids and alcohols associated with spoilage and inhibited the protein and lipid oxidation and degradation. Polyphenol treatments suppressed the formation of biogenic amines (lower levels of spermidine and 1-naphthylacetylspermine) and reduced fillet quality deterioration. It provided critical novel insights into the understanding of the molecular mechanism for inhibiting the quality deterioration of fillets treated with polyphenols during storage.

The inhibition mechanism of the texture deterioration of tilapia fillets during partial freezing after treatment with polyphenols.

The inhibition mechanism of the texture deterioration of tilapia fillets after treatment with polyphenols during partial freezing for 49 days was studied. Carnosic acid (CA), procyanidin (PA), quercetin (QE), and resveratrol (RSV) treatments had significantly higher hardness values (over 230 g) than the control group (183 g) on day 49 (P < 0.05). Polyphenol treatments were effective in delaying the protein degradation, lipid oxidation and spoilage microbe growth. Moreover, the kinetic model showed that the predicted shelf life of tilapia fillets treated with PA (102 d) was extended by 25 d compared to the control group (77 d). It was the proposed possible mechanism that polyphenols comprehensively maintained the protein conformation (increased hydrogen bonds and decreased disulfide bonds) and retarded protein denaturation and degradation, protecting the texture of the fillets. Therefore, polyphenols can be used to maintain texture and extend the shelf life of tilapia fillets during partial freezing.

Systems with Size and Energy Polydispersity: From Glasses to Mosaic Crystals.

We use Langevin dynamics simulations to study dense 2d systems of particles with both size and energy polydispersity. We compare two types of bidisperse systems which differ in the correlation between particle size and interaction parameters: in one system big particles have high interaction parameters and small particles have low interaction parameters, while in the other system the situation is reversed. We study the different phases of the two systems and compare them to those of a system with size but not energy bidispersity. We show that, depending on the strength of interaction between big and small particles, cooling to low temperatures yields either homogeneous glasses or mosaic crystals. We find that systems with low mixing interaction, undergo partial freezing of one of the components at intermediate temperatures, and that while this phenomenon is energy-driven in both size and energy bidisperse systems, it is controlled by entropic effects in systems with size bidispersity only.

The preservation effect of CGA-Gel combined with partial freezing on sword prawn (Parapenaeopsis hardwickii).

Effects of Chlorogenic acid-Gelatin (CGA-Gel) combined with partial freezing on quality change of sword prawn (Parapenaeopsis hardwickii) stored at -5 °C were evaluated for 23 days. Changes in sensory score, total viable counts (TVC), and physiochemical indexes including pH, total volatile basic nitrogen (TVB-N), thiobarbituric acid reactive substances (TBARS) and Ca2+-ATPase were examined. All shrimp treated with CGA and CGA-Gel had lower total viable counts compared to control (P < 0.05). The value of TVB-N and TBA of CGA-Gel treated group at day 13 were 18.4 mg N/100 g and 0.175 mg/100 g respectively, both below the proposed safe limits and values of CGA treated group. All the results demonstrated that Chlorogenic acid can inhibit growth of microorganism, lipid oxidation and protein degradation. CGA-Gel treated samples presented better quality preservation effects than CGA treated alone. Therefore, CGA-Gel combined with partial freezing is promising in sword prawn shelf life extension.

Postmortem nucleotide degradation in turbot mince during chill and partial freezing storage.

Nucleotide degradation in fish is an important biochemical change after death, which is closely related to freshness and sensory quality. However, except ATP-relative nucleotides, it remains unclear about changes in other nucleotide metabolites during postmortem stage. In this study, a strategy for the simultaneous quantification of 28 nucleobases, nucleosides, and nucleotides using hydrophilic interaction chromatography coupled with tandem mass spectrometry (HILIC-MS/MS) with positive/negative ion switching was developed. This method showed good linearity, precision, repeatability, and recovery. Furthermore, it was successfully applied to monitor the postmortem nucleotide degradation of turbot mince during chill (4 °C) and partial freezing (-3 °C) storage for 168 h. It was noted that the patterns of the changes in nucleotide metabolites differed considerably depending on the storage temperature. Meanwhile, the different pathway and speed of nucleotide catabolism in turbot mince was summarized based on the quantification data.

Changes in the quality of superchilled rabbit meat stored at different temperatures.

This work studied the effects of a superchilling process at two different temperatures on the shelf life and selected quality parameters of rabbit meat. As the storage time increased, the rates at which the total aerobic count, total volatile basic nitrogen, thiobarbituric acid-reactive substances and pH value increased were significantly lower in superchilled rabbit meat stored at -4°C compared to those in rabbit meat stored at -2.5°C and 4°C. SDS-PAGE analysis indicated that the decrease in storage temperature could significantly reduce the degree of protein degradation. The lightness, redness, shear force, the integrity of muscle microstructure and water holding capacity decreased with increasing storage time. Compared with the samples frozen at -18°C, superchilled rabbit meat shows a marked reduction in microstructure deterioration. These results suggest that shelf life of good-quality rabbit meat was 20d under superchilling at -2.5°C and at least 36d under superchilling at -4°C, compared with less than 6d under traditional chilled storage.