Search Results (85)

Freezing is a crucial technology for preserving food quality and extending shelf life. However, frozen storage often leads to protein oxidation, degradation, and cellular structural damage, compromising food palatability. To address these challenges, antifreeze substances have emerged as a promising solution. This review comprehensively summarizes the current research on antifreeze substances, including natural compounds and artificial analogs. For natural antifreeze substances, the mechanisms of antifreeze proteins (AFPs), antifreeze peptides (AFPPs), antifreeze polysaccharides (AFPLs), and antifreeze phosphates (AFPSs) are elucidated. Additionally, the preparation of artificial synthesis analogs and the application of antifreeze substances are discussed. By presenting their properties and research advancements, this review aims to provide a reference for the practical utilization of antifreeze substances in food-freezing applications. Full article

Developing safe and efficient cryoprotectants is critical for effective cryopreservation in biomedical applications. Inspired by natural antifreeze proteins (AFPs), a series of linear and star-shaped peptoids featuring isopropanol side chains to mimic the amphiphilic characteristics of threonine were prepared. The effects of chain length and molecular topology on antifreeze properties were systematically investigated. Both ice recrystallization inhibition (IRI) and ice crystal growth suppression improved with increasing chain length, and star-shaped peptoids exhibited superior performance. Notably, the star-shaped peptoid S-(A₆)₃ demonstrated excellent antifreeze activity and low cytotoxicity, highlighting its promise as a novel, non-toxic alternative to conventional cryoprotectants like DMSO. These findings provide valuable insight into the structure-property relationship of peptoids for cryopreservation applications. Full article

This review provides an overview of terrestrial extremophiles, highlighting their adaptive strengths and strategies for coping with environmental challenges through the use of specialized proteins. It also explores why their unique lifestyle and ability to adapt to extreme conditions have become a major focus of research, as well as the main benefits and advancements in the study of these organisms in recent decades. This review aims to present an objective summary of the knowledge acquired and its translation into applied science and biotechnological applications. Full article

The antifreeze and antioxidant capacities of tilapia (Oreochromis mossambicus) gelatin hydrolysates were investigated, after glycosylation with saccharides of varying molecular weights, to enhance their functional properties to widen its commercial application in frozen aquatic products. Glycosylation was conducted by mixing gelatin hydrolysates with ribose, glucose, maltose, and dextran (20 kDa) at a 1:1 mass ratio; the glycosylation products had a pH of 10 and were incubated at 80 °C for 1 h. The results showed that the glycosylation degree ranked as: ribose > glucose > maltose > dextran. The mass spectrometry analysis showed that 17, 32, and 5 glycosylation sites were identified for ribose, glucose, and maltose, respectively, suggesting a molecular weight-dependent effect. Spectroscopic analyses, including ultraviolet and infrared spectroscopy, revealed that the gelatin hydrolysate structure was expanded, with chromophores in hydrophilic environments; a blue shift in the amide A and II bands confirmed that the amino group was involved. Fluorescence spectroscopy showed conformational changes with a red shift at 303.4 nm and a reduction in intensity. Antifreeze activity, such as catalase freezing protection and shrimp surimi protein stability, and antioxidant activity, including radical scavenging and metal ion chelation, were significantly improved. Ribose exhibited the strongest effects, followed by maltose and glucose. These results demonstrate the potential of glycosylation to improve gelatin hydrolysates for functional applications. Full article

Cryopreservation can adversely affect sperm motility, structural integrity, and fertilization ability. This study investigated the effects of MitoQ and antifreeze protein III (AFP III) on frozen–thawed semen from eight adult dogs using a Tris–fructose extender. Ejaculates were divided and diluted with a standard Tris–fructose–egg yolk extender containing MitoQ (200 nM/mL) and AFP III (0.75, 1.0, 2.0 µg/mL), individually or combined. Post-thaw, samples were evaluated for motility, viability, membrane and acrosome integrity, lipid peroxidation, apoptosis indicators, mitochondrial function, and reactive oxygen species (ROS-H₂O₂). The results showed significant (p < 0.05) improvements in motility rate, progressive motility, VAP, VSL, VCL, ALH, and BCF with MitoQ or AFP alone. AFP III (0.75, 1.0 µg/mL) showed higher values than controls (p > 0.05), while MitoQ alone showed no significant effect. Viability and acrosome integrity improved with AFP III. Membrane integrity and lipid peroxidation were better in 0.75 and 1.0 µg/mL AFP III groups. ROS-H₂O₂ levels and mitochondrial membrane potential were unaffected except at 1.0 µg/mL AFP III. The phosphatidylserine translocation assay showed no significant differences in dead sperm between controls and individual treatments, but significant differences occurred with combined MitoQ/AFP III. In conclusion, AFP III and MitoQ in diluents protect canine sperm cells from cryodamage. Full article

Sliver carp is a nutritious and abundant species in China, but its low market value stems from its thin meat, small bones and strong odor. Processing it into surimi enhances its economic value, though surimi typically has low gel strength and is prone to deterioration. Recently, three-dimensional (3D) printing has gained attention as an innovative additive manufacturing technique for personalization and process simplification requiring high-performance materials. This study intended to develop an optimized surimi formula for 3D printing with dynamic high-pressure microfluidization (DHPM)-modified pea protein isolate (PPI) and microcrystalline cellulose (MCC). Firstly, the effect of DHPM on PPI properties was evaluated, followed by the optimization of the surimi gel formula (72.093% water content, 3.203% PPI, 1.728% MCC, 1% salt, 1% collagen peptide and 20.976% sliver carp paste) and 3D printing parameters (2000 mm/min at 25 °C with a 1.5 mm nozzle). Rheological comparisons between the optimized surimi, surimi with commercial antifreeze and surimi with only PPI or MCC indicated that the optimized formulation exhibited clearer 3D printing outlines and reduced stickiness due to a higher recovery and lower loss modulus. These results demonstrated that DHPM-treated PPI and MCC enhanced the 3D printability of silver carp surimi gel, providing a new idea for a surimi product and supporting its potential applications in food 3D printing. Full article

Antifreeze agents play a critical role in various fields including tissue engineering, gene therapy, therapeutic protein production, and transplantation. Commonly used antifreeze agents such as DMSO and other organic substances are known to have cytotoxic effects. Antifreeze proteins sourced from cold-adapted organisms offer a promising solution by inhibiting ice crystal formation; however, their effectiveness is hindered by a dynamic ice-shaping (DIS) effect and thermal hysteresis (TH) properties. In response to these limitations, antifreeze peptides (AFPs) have been developed as alternatives to antifreeze proteins, providing similar antifreeze properties without the associated drawbacks. This review explores the methods for acquiring AFPs, with a particular emphasis on chemical synthesis. It aims to offer valuable insights and practical implications to drive the realm of sub-zero storage. Full article

The Chinese rare minnow (Gobiocypris rarus), an important model fish in China, faces endangerment in the wild. Sperm cryopreservation facilitates the development of new strains and germplasm conservation, but the quality of its cryopreserved sperm remains low. This study evaluates the protective effects of different concentrations of antifreeze proteins (AFP I and AFP III) on the cryopreservation of Chinese rare minnow sperm. Cryopreserved sperm showed significant declines in progressive motility, curvilinear velocity (VCL), average path velocity (VAP), and lifespan compared to fresh sperm, except for straight-line velocity (VSL). The cryomedium containing 10 μg/mL AFP I improved these parameters to their highest levels. However, no significant difference was found in progressive motility and kinetic parameters between cryopreserved sperm with and without AFPs. Cryopreserved sperm with 10 μg/mL AFP I showed the highest plasma membrane integrity, mitochondrial activity, and DNA integrity, significantly better than without AFPs; importantly, the fertilization rate of cryopreserved sperm with 10 μg/mL AFP I was not significantly different from that of fresh sperm. These results indicate that the addition of 10 μg/mL AFP I to the cryomedium for Chinese rare minnow sperm does not improve kinetic parameters but significantly enhances sperm quality, aiding in its new strain development and germplasm conservation. Full article

Cryopreservation is a crucial technique for the long-term ex situ conservation of plant genetic resources, particularly in the context of global biodiversity decline. This process entails freezing biological material at ultra-low temperatures using liquid nitrogen, which effectively halts metabolic activities and preserves plant tissues over extended periods. Over the past seven decades, a plethora of techniques for cryopreserving plant materials have been developed. These include slow freezing, vitrification, encapsulation dehydration, encapsulation–vitrification, droplet vitrification, cryo-plates, and cryo-mesh techniques. A key challenge in the advancement of cryopreservation lies in our ability to understand the molecular processes underlying plant freezing tolerance. These mechanisms include cold acclimatization, the activation of cold-responsive genes through pathways such as the ICE–CBF–COR cascade, and the protective roles of transcription factors, non-coding RNAs, and epigenetic modifications. Furthermore, specialized proteins, such as antifreeze proteins (AFPs) and late embryogenesis abundant (LEA) proteins, play crucial roles in protecting plant cells during freezing and thawing. Despite its potential, cryopreservation faces significant challenges, particularly in standardizing protocols for a wide range of plant species, especially those from tropical and subtropical regions. This review highlights the importance of ongoing research and the integration of omics technologies to improve cryopreservation techniques, ensuring their effectiveness across diverse plant species and contributing to global efforts regarding biodiversity conservation. Full article

The effects of MRS, whey protein and blueberry alone, and mixed fermentation on the survival rate of lactic acid bacteria under various freeze-drying conditions were investigated. The surface structure of the freeze-dried powders was also investigated to explore the anti-freezing protection mechanism of mixed whey protein and blueberry fermentation on the bacteria. It was found that the mixed fermentation medium of blueberry and whey protein has a protective effect on the freeze-drying bacteria and is better than the traditional MRS and whey protein medium. The optimal concentration of blueberry juice addition was 9%. The survival rate of the pre-freezing temperature at −80 °C was higher than at −20 °C after the pre-freezing and freeze-drying processes. The freeze-drying thickness of 0.3 cm could improve the survival rate of the bacteria. The Fourier transform infrared spectroscopy results indicated the interaction between the whey protein, anthocyanins, and the surface composition of the lactic acid bacteria. Full article

In this study, ultrafiltration fractions (<3 k Da, LMH; >3 k Da, HMH) and solid-phase extraction fractions (hydrophilic hydrolysate, HIH; hydrophobic hydrolysate, HOH) from trypsin hydrolysate purified from croceine croaker (Pseudosciaena crocea) isolate were obtained to investigate the cryoprotective effects of the different fractions, achieved by means of maceration of turbot fish meat after three freeze-thaw cycles. Alterations in the texture, color, moisture loss, myofibrillar protein oxidation stability and conformation, and microstructure of the fish were analyzed after freezing and thawing. The results demonstrate that HIH maximized the retention of fish texture, reduced moisture loss, minimized the oxidation and aggregation of myofibrillar proteins, and stabilized the secondary and tertiary structures of myofibrillar proteins compared to the control group. In conclusion, the HIH component in the trypsin hydrolysates of croceine croaker significantly contributes to minimizing freeze damage in fish meat and acts as an anti-freezing agent with high industrial application potential. Full article

Ice detection poses significant challenges in sectors such as renewable energy and aviation due to its adverse effects on aircraft performance and wind energy production. Ice buildup alters the surface characteristics of aircraft wings or wind turbine blades, inducing airflow separation and diminishing the aerodynamic properties of these structures. While various approaches have been proposed to address icing effects, including chemical solutions, pneumatic systems, and heating systems, these solutions are often costly and limited in scope. To enhance the cost-effectiveness of ice protection systems, reliable information about current icing conditions, particularly in the early stages, is crucial. Ultrasonic guided waves offer a promising solution for ice detection, enabling integration into critical structures and providing coverage over larger areas. However, existing techniques primarily focus on detecting thick ice layers, leaving a gap in early-stage detection. This paper proposes an approach based on high-order symmetric modes to detect thin ice formation with thicknesses up to a few hundred microns. The method involves measuring the group velocity of the S₁ mode at different temperatures and correlating velocity changes with ice layer formation. Experimental verification of the proposed approach was conducted using a novel group velocity dispersion curve reconstruction method, allowing for the tracking of propagating modes in the structure. Copper samples without and with special superhydrophobic multiscale coatings designed to prevent ice formation were employed for the experiments. The results demonstrated successful detection of ice formation and enabled differentiation between the coated and uncoated cases. Therefore, the proposed approach can be effectively used for early-stage monitoring of ice growth and evaluating the performance of anti-icing coatings, offering promising advancements in ice detection and prevention for critical applications. Full article

Antifreeze peptides have become effective antifreeze agents for frozen products, but their low quantity of active ingredients and high cost limit large-scale application. This study used the glycosylation of fish collagen peptides with glucosamine hydrochloride catalyzed by transglutaminase to obtain a transglutaminase-catalyzed glycosylation product (TGP) and investigate its antifreeze effect on tilapia. Compared with the blank group, the freshness (pH value of 6.31, TVB-N value of 21.7 mg/100 g, whiteness of 46.28), textural properties (especially hardness and elasticity), and rheological properties of the TGP groups were significantly improved. In addition, the protein structures of the samples were investigated using UV absorption and fluorescence spectroscopy. The results showed that the tertiary structure of the TGP groups changed to form a dense polymer. Therefore, this approach can reduce the denaturation and decomposition of muscle fibers and proteins in fish meat more effectively and has a better protective effect on muscle structure and protein aggregation, improving the stability of fish meat. This study reveals an innovative method for generating antifreeze peptides by enzymatic glycosylation, and glycosylated fish collagen peptide products can be used as new and effective green antifreeze agents in frozen foods. Full article

The development of nontoxic and efficient antifreeze agents for organ cryopreservation is crucial. However, the research remains highly challenging. In this study, we designed and synthesized a series of peptoid oligomers using the solid-phase submonomer synthesis method by mimicking the amphiphilic structures of antifreeze proteins (AFPs). The obtained peptoid oligomers showed excellent antifreeze properties, reducing the ice crystal growth rate and inhibiting ice recrystallization. The effects of the hydrophobicity and sequence of the peptoid side chains were also studied to reveal the structure–property relationship. The prepared peptoid oligomers were detected as non-cytotoxic and considered to be useful in the biological field. We hope that the peptoid oligomers presented in this study can provide effective strategies for the design of biological cryoprotectants for organ preservation in the future. Full article

Aquatic products are gaining popularity due to their delicacy and high nutrient value. However, they are perishable, with a short shelf-life. Frozen storage is associated with adverse effects, leading to protein oxidation and degradation, thereby altering the protein’s structural integrity and subsequently influencing the palatability of protein-based food products. To address these challenges, novel antifreeze peptides have gained significant attention. Antifreeze peptides are a class of small molecular weight proteins or protein hydrolysates that offer protection to organisms in frozen or sub-frozen environments. They offer distinct advantages over conventional commercial antifreeze agents and natural antifreeze proteins. This review provides an overview of the current state of research on antifreeze agents, elucidates their characteristics and mechanisms, and examines their applications in aquatic products. Furthermore, the article offers insights into the prospective development and application prospects of antifreeze peptides. Full article