Ice Crystals Research Articles

Tailoring an egg white protein double network emulsion gel as a novel fat substitute for improving freeze-thaw stability of minced meat gel

This work aimed to investigate the effect of double network emulsion gel (DNEG) as a substitute for pork back fat (PBF) on the freeze-thaw stability of minced meat gel (MMG). We used slow acidification with glucono-δ-lactone (GDL) to induce egg white protein (EWP) gelation, while CaCO3 was affected by acidification to release Ca2+ to cross-link sodium alginate (SA), resulting in the gradual formation of DNEG networks. The MMG prepared using DNEG substitute for PBF had fine hardness and color after 5 freeze-thaw cycles (FTCs). This was due to the excellent plasticity of DNEG, which made it more capable of filling the voids of minced meat products, thus reducing the space for ice crystal growth. As a result, MMG prepared with DNEG could pass through the maximum ice crystal formation zone faster and avoid damage due to the formation of larger ice crystals. Notably, DNEG provided a barrier for the migration of immobilized water to bulk water in the sample. After several freeze-thaw treatments, the water holding capacity of samples prepared with DNEG decreased significantly slower, which slowed down the oxidation and decomposition of meat proteins. In summary, this study revealed the role of fat substitute DNEG as a favorable filling material for improving the freeze-thaw stability of minced meat products, and provided a technical reference for the development of healthy and storable meat products.

To What Extent Do Low-Voltage Electrostatic Fields Play a Role in the Physicochemical Properties of Pork during Freezing and Storage?

Low-voltage electrostatic fields (LVEF) are recognized as a new technology that can improve the quality of frozen meat. To determine the extent to which LVEF assistance affects the quality of frozen pork for long-term storage, pork was frozen and stored at -18 and -38 °C for up to 5 months. Water-holding capacity, muscle microstructure, and protein properties were investigated after up to 5 months of frozen storage with and without LVEF assistance. In comparison to traditional -18 and -38 °C frozen storage, LVEF treatment inhibited water migration during frozen storage and thawing. As a result, thawing losses were reduced by 15.97% (-18 °C) and 3.38% (-38 °C) in LVEF-assisted compared to conventional freezing methods. LVEF helped to maintain the muscle fiber microstructure and reduce muscle protein denaturation by miniaturizing ice crystal formation by freezing. As a result of this study, LVEF is more suitable for freezing or short-term frozen storage, while a lower temperature plays a more significant role in long-term frozen storage.

Controlling the Architecture of Freeze-Dried Collagen Scaffolds with Ultrasound-Induced Nucleation.

Collagen is a naturally occurring polymer that can be freeze-dried to create 3D porous scaffold architectures for potential application in tissue engineering. The process comprises the freezing of water in an aqueous slurry followed by sublimation of the ice via a pre-determined temperature-pressure regime and these parameters determine the arrangement, shape and size of the ice crystals. However, ice nucleation is a stochastic process, and this has significant and inherent limitations on the ability to control scaffold structures both within and between the fabrication batches. In this paper, we demonstrate that it is possible to overcome the disadvantages of the stochastic process via the use of low-frequency ultrasound (40 kHz) to trigger nucleation, on-demand, in type I insoluble bovine collagen slurries. The application of ultrasound was found to define the nucleation temperature of collagen slurries, precisely tailoring the pore architecture and providing important new structural and mechanistic insights. The parameter space includes reduction in average pore size and narrowing of pore size distributions while maintaining the percolation diameter. A set of core principles are identified that highlight the huge potential of ultrasound to finely tune the scaffold architecture and revolutionise the reproducibility of the scaffold fabrication protocol.

Plant Cryopreservation: Principles, Applications, and Challenges of Banking Plant Diversity At Ultralow Temperatures.

Progressive loss of plant diversity requires the protection of wild and agri-/horticultural species. For species whose seeds are extremely short-lived, or rarely or never produce seeds, or whose genetic makeup must be preserved, cryopreservation offers the only possibility for long-term conservation. At temperatures below freezing, most vegetative plant tissues suffer severe damage from ice crystal formation and require protection. In this review, we describe how increasing the concentration of cellular solutes by air drying or adding cryoprotectants, together with rapid cooling, results in a vitrified, highly viscous state in which cells can remain viable and be stored. On this basis, a range of dormant bud-freezing, slow-cooling, and (droplet-)vitrification protocols have been developed, but few are used to cryobank important agricultural/horticultural/timber and threatened species. To improve cryopreservation efficiency, the effects of cryoprotectants and molecular processes need to be understood and the costs for cryobanking reduced. However, overall, the long-term costs of cryopreservation are low, while the benefits are huge. Expected final online publication date for the Annual Review of Plant Biology, Volume 75 is May 2024. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Use of ultrasound and NIRs as tools for monitoring ice formation in superchilled meat

This study aimed to gain a deeper understanding of the ice crystal formation during the superchilling process (SC) of meat by using non-destructive methods. Ultrasound inspection was performed considering the ultrasonic pulse velocity (UPV), while Near Infrared Spectroscopy (NIR) measurements were carried out with a spectral range of 950–1650 nm. Signals from both methodologies were periodically taken during the controlled freezing of 8 beef cubic samples of (6 cm3). Obtained results revealed that both methods have the ability to detect the ice crystal formation during the SC process, and particularly during the period of thermal arrest. Hence, these results evidence that ultrasound inspection and NIR, combined with Multivariate Statistical Process Control charts, could be implemented as quality control procedures during the SC process of muscle foods, allowing a more accurate control of the process and thus, minimizing the potential deleterious effects of ice crystals formation in meat.

Graph-Neural-Network-Based Unsupervised Learning of the Temporal Similarity of Structural Features Observed in Molecular Dynamics Simulations.

Classification of molecular structures is a crucial step in molecular dynamics (MD) simulations to detect various structures and phases within systems. Molecular structures, which are commonly identified using order parameters, were recently identified using machine learning (ML), that is, the ML models acquire structural features using labeled crystals or phases via supervised learning. However, these approaches may not identify unlabeled or unknown structures, such as the imperfect crystal structures observed in nonequilibrium systems and interfaces. In this study, we proposed the use of a novel unsupervised learning framework, denoted temporal self-supervised learning (TSSL), to learn structural features and design their parameters. In TSSL, the ML models learn that the structural similarity is learned via contrastive learning based on minor short-term variations caused by perturbations in MD simulations. This learning framework is applied to a sophisticated architecture of graph neural network models that use bond angle and length data of the neighboring atoms. TSSL successfully classifies water and ice crystals based on high local ordering, and furthermore, it detects imperfect structures typical of interfaces such as the water-ice and ice-vapor interfaces.

Tunable tip singularity of a water droplet freezing on surfaces under forced convection

Typically, a water droplet on surfaces freezes with a tip singularity on the top in an experimental environment, and the magnitude of the singular tip is thought to be a constant of ∼ 131°. Interestingly, we observed that the tip magnitude can be variable from 131° to 180° (i.e., disappearing) under a ubiquitous convection environment. Especially, dependent on the competition between heat conduction (influenced by contact angle and substrate temperature) and convection, the traditional concave freezing front and a newly found convex freezing front were both observed during the freezing process, respectively corresponding to the emergence and disappearance of the singular tip. Additionally, an analytical model was proposed to clarify the variable mechanisms of tip singularity and the quantitative relationship between the magnitude of tip and the curvature of the ice-water interfaces during freezing. This study advances our understanding of freezing dynamics and ice crystal geometry. Simultaneously, the inhibition effect of convection on the singular ice crystals may provide a promising method for mitigating mechanical damage caused by sharp ice crystals during cryopreservation.

Ice templated and ice seed tailored hydrogels for highly efficient solar evaporator

In recent years, freshwater resources have become a global concern, and solar vapor generation (SVG) has garnered significant attention from researchers. Herein, a novel hydrogel solar evaporator was prepared by incorporating lignin and CuS-rGO into a chitosan-gelatin matrix. The anisotropic and isotropic morphologies of the hydrogel were prepared by pathway control on the solidification velocities of ice crystals and ice seeds. It presented that the anisotropic morphology can improve the refraction of light and increase the utilization rate of light by forming a light trap, leading to higher water evaporation rate. Additionally, ice seed was introduced during the freezing process, producing an anisotropic hydrogel with curled layer structure that endowed lower enthalpy of water evaporation and faster water transfer rate, resulting in high evaporate of 3.62 kg m−2 h−1 under one solar irradiation with photothermal conversion efficiency of 97.7 %. Finally, the gel also demonstrated good mechanical properties, long-term working stability and harsh environment tolerance, which make it ideal for outdoor applications. The hydrogel evaporator had potential to generate 25.24 kg m2 water per day that could meet the huge demand for freshwater as sources.

Psychrophiles to control ice-water phase changes in frost-susceptible soils

The phase changes of soil water or porous media have a crucial influence on the performance of natural and man-made infrastructures in cold regions. While various methods have been explored to address the impacts of frost-action arising from these phase changes, conventional approaches often rely on chemicals, mechanical techniques, and the reuse of waste materials, which often exhibit certain limitations and environmental concerns. In contrast, certain organisms produce ice-binding proteins (IBPs) or antifreeze proteins (AFPs) to adapt to low temperatures, which can inhibit ice crystal growth by lowering the freezing point and preventing ice crystallization without the need for external intervention. This study explores the potential of three psychrophilic microbes: Sporosarcina psychrophile, Sporosarcina globispora, and Polaromonas hydrogenivorans, to induce non-equilibrium freezing point depression and thermal hysteresis in order to control ice lens growth in frost-susceptible soils. We hypothesize that the AFPs produced by psychrophiles will alter the phase changes of porous media in frost-susceptible soils. The growth profiles of the microbes, the concentration of released proteins in the extracellular solution, and the thermal properties of the protein-mixed soils are monitored at an interval of three days. The controlled soil showed a freezing point of − 4.59 °C and thermal hysteresis of 4.62 °C, whereas protein-treated soil showed a maximum freezing point depression of − 8.54 °C and thermal hysteresis of 7.71 °C. Interestingly, except for the controlled sample, all the protein-treated soil samples were thawed at a negative temperature (minimum recorded at − 0.85 °C). Further analysis showed that the treated soils compared to porous media mixed soil freeze (1.25 °C vs. 0.51 °C) and thaw (2.75 °C vs. 1.72 °C) at extensive temperature gap. This freezing and thawing temperature gap is the temperature difference between the beginning of ice core formation and completed frozen, and the beginning of ice core thawing and completed thawed for the treated soil samples selected from different incubation days. Overall, this study presents a novel bio-mediated approach using psychrophilic microbes to control ice formation in frost-susceptible soils.

STUDYING THE SOLUBILITY OF THE SYSTEM ZnSO4 - KNO3 - H2O

The solubility of the components in the ZnSO4 - KNO3 - H2O system was studied by the visual-polythermal method in the temperature range from -7.0°С to 42.0°С. The phase diagram delimits the fields of ice crystallization, KNO3, K2SO4·ZnSO4·6H2O, and ZnSO4. A solubility diagram was constructed, and a new compound K2SO4·ZnSO4·6H2O was separated. The new compound was identified by chemical, X-ray phase, thermogravimetric, and IR spectroscopic analysis.

The Influence of Whey Protein Isolate on the Quality Indicators of Acidophilic Ice Cream Based on Liquid Concentrates of Demineralized Whey.

The use of liquid whey concentrates in the composition of ice cream, especially in combination with other powdered whey proteins, is limited due to their understudied properties. This article shows the main rheological and thermophysical characteristics of ice cream mixes, as well as color parameters, microstructure, analysis of ice crystals and quality indicators of ice cream during storage. The most significant freezing of free water (p ≤ 0.05) was observed in the temperature range from the cryoscopic temperature to -10 °C. The microscopy of experimental ice cream samples based on hydrolyzed whey concentrates indicates the formation of a homogeneous crystalline structure of ice crystals with an average diameter of 13.75-14.75 μm. Microstructural analysis confirms the expediency of using whey protein isolate in ice cream, which ensures uniform distribution of air bubbles in the product and sufficient overrun (71.98-76.55%). The combination of non-hydrolyzed whey concentrate and 3% whey protein isolate provides the highest stability to preserve the purity and color intensity of the ice cream during storage. The produced ice cream can be classified as probiotic (number of Lactobacillus acidophilus not lower than 6.2 log CFU/g) and protein-enriched (protein supply from 15.02-18.59%).

Effect of liquid nitrogen spray freezing on the ice crystal size and quality of large yellow croaker

Large yellow croakers (Larimichthys crocea) were frozen by liquid nitrogen spray freezing (LNSF), liquid immersion freezing (LIF), and air freezing (AF), and the freezing rate, ice crystal size and product qualities were compared. LNSF was found to be a promising freezing technology because of the significantly (P < 0.05) shortest freezing time, smallest ice crystal, and best overall product quality. Then, the effect of processing parameters during LNSF on freezing characteristics, and microstructure and qualities of samples was studied. Freezing time was reduced by decreasing freezing temperature and increasing air velocity. A size uniformity index was proposed in this study to evaluate the distribution uniformity of ice crystals. The minimum cross-sectional area (605.83 μm2) with the best size uniformity was achieved at a freezing temperature of −90 °C, a final temperature of −30 °C, and an air velocity of 4 m/s, showing a reduction of 50.90% as compared to the maximum (1233.77 μm2). The qualities of samples frozen by LNSF with the aforementioned parameter values were well maintained and met the industrial standard. Therefore, the developed LNSF protocol was recommended for the industrial application for large yellow croaker.

Unraveling the molecular freezing behavior of water on a calcium silicate hydrate matrix.

The hydration process of cement-based materials primarily results in the formation of calcium silicate hydrate (CSH), which is crucial in deciding how long concrete will last. This study utilizes molecular dynamics simulation technology to explore the freezing behavior of pure water solutions within various calcium silicate hydrate (CSH) matrices. The investigated matrices encompass four different Ca/Si ratios. According to the simulation, as ice crystals develop close to the surface of CSH, the CSH matrix strengthens its hydrogen and ionic interactions with water molecules, which effectively prevents water molecules from crystallizing and nucleating. Consequently, these molecules compose an unfrozen water film structure that bridges between ice crystals and the CSH matrix. The research also reveals an intriguing relationship between silica chain behavior on the Ca/Si ratio and the CSH surface. Surface flaws arise as a result of the silica chains of CSH breaking into shorter segments as the Ca/Si ratio increases. These surface defects manifest as grooves on the matrix's surface, effectively capturing and retaining specific water molecules. The CSH matrix's hydrogen bonds with water molecules are weakened as a result of this process, facilitating their participation in the crystallization process, and leading to a thinner unfrozen water film thickness with an increased Ca/Si ratio. This study contributes to a greater knowledge of the performance and dependability of cement-based products by offering molecular-level insights into the freezing actions of liquids in gel pores.

Freezing-enhanced chlorination of organic pollutants for water treatment.

Freezing has been reported to accelerate chemical reactions and thus affect the fate of pollutants in the environment. However, little research has been conducted on the potential effects of freezing on the chlorination process. This study aimed to explore the freezing-enhanced chlorination process by comparing the oxidation of clofibric acid (CA) by chlorine in ice (at -20 °C) to the same reaction in water (at 25 °C). The degradation of CA, which was negligible in water, was significantly accelerated in ice. This acceleration can be attributed to the freeze concentration effect that occurs during freezing, which excludes solutes such as chlorine, CA and protons from the ice crystals, leading to their accumulated concentration in the liquid brine. The increased concentration of chlorine and protons in the liquid brine leads to higher rates of CA oxidation, supporting the freeze concentration effect as the underlying cause for the accelerated chlorination of CA in ice. Moreover, the chlorine/freezing system was also effective in the degradation of other organic pollutants. This highlights the environmental relevance and significance of freezing-enhanced chlorination in cold regions, particularly for the treatment of organic contaminants.

Ice crystal guided folding of graphene oxides in a confined space: a facile approach to 1D functional graphene structures.

The controlled conformational changes of planar graphene nanosheets are of great importance to the realization of their practical applications. Despite substantial effort in the area, the controlled folding of two-dimensional (2D) graphene sheets into one-dimensional (1D) structures still remains a significant challenge. Here, for the first time, we report an ice crystal guided folding strategy to fabricate 1D folded graphene nanobelts (FGBs), where the formation and growth of ice crystals in a confined space function to guide the folding of 2D graphene oxide (GO) nanosheets into 1D nanobelts (i.e. folded graphene oxide belts, FGOBs), which were subsequently converted to FGBs after annealing. Thin aqueous GO containing films were obtained by blowing air through a GO dispersion in the presence of a surfactant, polyoxypropylenediamine (D400), resulting in a foam containing uniform air bubbles. Subsequent shock cooling of the foam using liquid nitrogen resulted in the facile fabrication of FGOBs. This technique provides a general approach to encapsulate catalytic nanomaterials such as Fe3O4 nanorods, TiO2 and Co3O4 nanoparticles into the folded graphene structure for practical applications such as Li-ion batteries.

Responses of Simulated Arctic Mixed-Phase Clouds to Parameterized Ice Particle Shape

Abstract In simulations of Arctic mixed-phase clouds, cloud persistence and the liquid water path (LWP) are sensitive to ice particle number concentrations. Here, we explore sensitivities of cloud microphysical properties to the dominant ice particle shape (dendrites, plates, columns, or spheres) using the SCALE-AMPS large-eddy simulation model. AMPS is a bin microphysics scheme that predicts particle shapes based on the inherent growth ratio (IGR) of spheroids, which determines vapor depositional growth rates along the a and c axes, and the rimed and aggregate mass fractions. We examine the impacts of various IGR values on simulations of clouds observed during the M-PACE and SHEBA experiments. Under M-PACE (SHEBA) conditions, LWP varies between 49 (1.1) and 230 (6.7) g m−2, and the ice water path (IWP) varies between 3 (0.03) and 40 (0.12) g m−2, depending on the ice shape. The lowest LWP and the highest IWP are obtained when columnar particles dominate because their low terminal velocities and large capacitance and collisional area result in large vapor deposition and riming rates, whereas the highest LWP and lowest IWP are obtained when spherical particles dominate because their vapor deposition and riming rates are low. Because ice particle shape significantly influences simulated Arctic mixed-phase clouds, reliable simulations require accurately estimated IGR values under various atmospheric conditions. Finally, comparisons between the simulation results and observations show that the size distribution larger than 2000 μm is better reproduced when the increase in rimed mass that causes ice particles to become spherical is suppressed. Significance Statement Atmospheric models have difficulties in reproducing Arctic mixed-phase clouds because of uncertainties in the parameterization of microphysical processes. This is the first study to use a large-eddy simulation model implemented with a habit-predicting bin microphysics scheme to demonstrate the important role of ice particle shape on the microphysical properties of both heavy-riming and no-riming mixed-phase clouds. We found the vapor deposition and riming rates to be greatly influenced by ice particle shape. By comparing the ice particle size distribution, mass–diameter relationship, and area ratio between simulation results and observations, we show that a hexagonal ice shape model and a riming model that simply converts ice crystals to graupel may not accurately reproduce actual heavy-riming clouds.

Research on the effect of microelement salt with fertilizer

The visual-polythermal method was used to study the solubility of components in the ZnSO4 – (NH4)2SO4 – H2O system over the temperature interval of -22.0°С to +36.1°С. Solubility and characteristics of the constituents of the system at different temperatures and concentrations were studied to show the physicochemical interactions between zinc sulfate and ammonium sulfate. The phase description delineates the areas of ice crystallization, (NH4)2SO4, ZnSO4ꞏ(NH4)2SO4ꞏ6H2O, and ZnSO4. A solubility diagram was drawn and a new compound, ZnSO4ꞏ(NH4)2SO4ꞏ6H2O, was isolated. The system ZnSO4 – (NH4)2SO4 – H2O was investigated using thirteen inner sections. At the double and triple points of the system, the equipoise composition of solutions and crystallization temperatures were clarified. The analysis was carried out using contemporary physicochemical analysis methods to confirm the identity of the obtained compound. Analytical data on physicochemical changes, thermal stability and chemical decomposition of the ZnSO4ꞏ(NH4)2SO4ꞏ6H2O sample with temperature change were presented. All the diffractographic changes in the X-ray pattern of a new compound, in particular, the set of distances between the planes, the activation of their reflection angles, and the diffraction lines confirm the individuality of the new compound.

Solubility in manganese sulfate-ammonium sulfate-water system

The production of phosphorus-containing fertilizers involves the use of mineral acids and phosphate raw materials. In the production process and finished fertilizers, the existence of calcium phosphates, ammonium, sulfuric or nitric and phosphoric acids is possible. Enriched superphosphate contains monocalcium phosphate, calcium sulfate dihydrate, phosphoric acid. During ammoniation, monoammonium phosphate can also be formed. The solubility of the components in the manganese sulfate-ammonium sulfate-water system was studied by the visual-polythermal method in the temperature range from -1.0°С to 27.0°С. The phase diagram limits the regions of ice crystallization, ammonium sulfate, manganese sulfate and chemical compound. A solubility diagram was plotted and a new compound (ammonium sulfate + marganes sulfate + water) (NH4)2Mn(SO4)2*6H2O was isolated. The new compound was identified by chemical, X-ray diffraction, thermogravimetric and IR spectroscopic analyses. To physicochemically substantiate the behavior of marganese sulfate under the conditions of production of enriched superphosphate, the interaction of marganese sulfate with monocalcium phosphate was studied by the method of isomolar series in 0.01 M solutions.

Observation Method of Microphysical Parameters of Ice Crystals in Cloud Based on Digital Holography

Observation Method of Microphysical Parameters of Ice Crystals in Cloud Based on Digital Holography

Tuning the low-temperature phase behavior of aqueous ionic liquids.

Water's anomalous behavior is often explained using a two-liquid model, where two types of water, high-density liquid (HDL) and low-density liquid (LDL), can be separated via a liquid-liquid phase transition (LLPT) at low temperature. Mixtures of water and the ionic liquid hydrazinium trifluoroacetate were suggested to also show an LLPT but with the advantage that there is no rapid ice crystallization hampering its observation. It remains controversial whether these solutions exhibit an LLPT or are instead associated with complex phase separation phenomena. We here show detailed low-temperature calorimetry and diffraction experiments on aqueous solutions containing hydrazinium trifluoroacetate and other similar ionic liquids, all at a solute mole fraction of x = 0.175. Hydrazinium trifluoroacetate, ammonium trifluoroacetate, ethylammonium trifluoroacetate and hydrazinium pentafluoropropionate all boast exothermic transitions unrelated to crystallization as well as remarkable structural changes upon cooling into the glassy state. We propose a model inspired by micelle formation and decomposition in surfactant solutions, which is complemented by MD simulations and allows rationalizing the rich phase behavior of our mixtures during cooling. The fundamental aspect of the model is the hydrophobic nature of fluorinated anions that enables aggregation, which is reversed upon cooling and culminates in the remarkable exothermic first-order transition observed at low temperature. That is, we assign the first-order transition not to an LLPT but to phase-separations similar to the ones when falling below the Krafft temperature. All other solutions merely show simple vitrification behavior. Still, they exhibit distinct differences in liquid fragility, which is decreased continuously with decreasing hydrophobicity of the anions. This might enable the systematic tuning of ionic liquids with the goal of designing aqueous solutions of specific fragility.