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The snow crystal morphology diagram. Different types of snow ice single crystals that grow in air at atmospheric pressure as a function of temperature and water vapor super- 

The snow crystal morphology diagram. Different types of snow ice single crystals that grow in air at atmospheric pressure as a function of temperature and water vapor super- 

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Freezing is the process of ice crystallization from supercooled water. Ice crystal morphology plays an important role in the textural and physical properties of frozen and frozen-thawed foods and in processes such as freeze drying, freeze concentration, and freeze texturization. Size and location of ice crystals are key in the quality of thawed tis...

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... relates to the physical form and structure of a material. The term includes a wide range of characteristics, extending from dimensions of a crystal lattice to the external size and shape of large objects. In the case of ice in nature, morphology means characterizing the structure at scales ranging from crystal lattices to supra-crystalline structures such as needles, plates and columns, and macro- structures such as floes (sheets of floating ice) and glaciers. In the context of this article, “ ice morphology ” will be understood as those parameters that allow characterization of the forms adopted by ice in liquid and solid foods that are relevant to their properties. However, to get an appreciation of the nomenclature of ice crystal structures and the variables influencing their formation, a short description of snow crystal morphology follows. The morphology of snow crystals (i.e., ice crystals growing from supersatured water vapor) exhibits a complex and puzzling dependence of temperature and supersaturation (Figure 3). Snow crystal growth is typically dominated by the kinetics of molecular attachment in combination with the already mentioned transport effects: mass diffusion, which carries water molecules to the growing crystal, and heat diffusion, which removes the heat generated by solidification. The interplay of these three processes is ultimately responsible for the vast diversity of snow crystal morphologies. However, the specific physical mechanisms responsible for the unusual temperature dependence of the morphology of growing ice crystals is still not well understood. 48 Some authors have classified the snow crystal morphology into primary and secondary habits of single crystals. The primary habit of single crystals depends on the aspect radio Г between the maximum length 2 c and the maximum width 2 a along the axis ( Г = c / a ; see Figure 4). The secondary habit corresponds to the finer details of shape, such as the amount of hollowing, and the number and shape of branches or needles. Except at the lowest supersaturation, the primary habit in an inert gas atmosphere depends only on temperature, whereas the secondary habit changes with time, temperature, supersaturation, crystal size, vapor mean free path, and thermal conductivity of the air. Both habits are also sensitive to small concentrations of gaseous impurities. 49 Polymorphism of ice occurs not only at the atomic level, i.e., as previously explained, but also by “ macroscopic polymorphism ”— a multiplicity of macroscopic shapes or patterns of crystals which grow under highly nonequilibrium conditions yielding a specific structure. 50 The final ice crystal morphology depends on the conditions under which the crystal was formed and grown as well as the rate of crystal growth, temperature, and the presence of solutes. 4 Of particular importance is the fact that the oriented nature of ice Ih leads to unequal growth rates on different crystal surfaces (termed anisotropic growth). In particular, growth is much more rapid in both the primary and secondary prism plane directions than in the basal plane direction. Therefore, at low degree of supercooling, this leads to ice crystals with disk morphologies. 42 As mentioned before, an important condition under which the ice crystal is formed is supercooling. Shibkov et al. 50,51 investigated the morphology of ice crystals freely grown from supercooled water finding that when supercooling increased from 0.1 °C to about 30 °C, the different structures of growing ice changed sequentially from disk, to perturbed disk, to a dense-branching morphology due to splitting of the fingertips, to dendrite, to stable needle, to fractal needled branch, to compact needled branch, and, finally, to platelet. In solutions, three patterns of growth of ice crystals around nuclei may arise 52 : (1) if the molecules of water are given enough time, they arrange themselves regularly into hexagonal crystallization units called dendrites (see Figure 5); (2) if they become incorporated at a fast rate into the crystal at odd places, they construct units called “ irregular dendrites ” or axial columns that originate from the center of crystallization; and (3) at higher cooling rates, many ice spears originate from the center without side branches; these units are called spherulites. However, the only ice crystal form of importance in most foods is the hexagonal crystallization unit or “ regular dendrite. ” 14 Dendrite morphology is defined by sinusoidal perturbations at the solid – liquid interface. The wavelength of these perturbations is dependent on the rate of crystalline growth, the temperature gradient in frozen region, and the degree of supercooling. There is a threshold wavelength which leads to the formation of stable dendrites; below this critical wavelength, the perturbations disappear. This limit is known as the limit of morphological stability and is used to define the crystal size in relation to freezing kinetics. ...

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Citations

... The presence of water in the product influences the protein denaturation (Vanzi et al., 1998), starch gelatinization (Slade & Levine, 1993), and also the state transitions in amorphous food components (Matveev et al., 2000). Freezing of water involves the formation of ice resulting from the crystallization of pure water present in the food product and is important in determining the process efficiency and quality of the food products (Petzold and Aguilera, 2009). The degree of ice formation in food products depends upon the freezing temperature. ...
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Understanding food materials from the classical realm of physics including soft condensed matter physics has been an area of interest, especially in the structural design engineering of food products. The contents of this review would help the reader in understanding the thermodynamics of food polymer, structural design principles, structural hierarchy, steps involved in food structuring, newer structural design technologies, and structure measurement techniques. Understanding the concepts of free volume would help the food engineers and technologists to study the food structural changes, manipulate process parameters and, the optimum amount of nutraceuticals/ingredients to be loaded in the food matrix. Such understanding helps in reducing food ingredient wastage while designing a food product.
... It has been suggested that large crystals with sharp edges can rupture cell walls and contribute to texture deterioration due to drip water loss [110], whereas rapid freezing generates small, fine intracellular crystals in the muscle, which are evenly distributed and do not cause significant losses [109]. Therefore, the speed of freezing is the parameter used to control the size and distribution of ice crystals in the system [111]. A further complication is recrystallisation, which occurs due to temperature fluctuations during freezing, causing the formation of larger crystals from the smaller crystals formed at the beginning [112]. ...
... A further complication is recrystallisation, which occurs due to temperature fluctuations during freezing, causing the formation of larger crystals from the smaller crystals formed at the beginning [112]. It is the process in which, over time, the average size of ice crystals increases, and their number decreases due to the redistribution of water from smaller ice crystals to larger ones [111]. One way to prevent recrystallisation is to keep the temperature constant throughout the storage process of frozen meat [3]. ...
... To obtain good freezing results, several strategies have been applied to increase the heat extraction rate, however, for this, the product should ideally be small and individually frozen. Freezing large products only results in the formation of large crystals that reduce the quality of the food [111]. New preservation technologies have been explored to improve the quality of meat reaching the consumer. ...
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Meat refers to animal tissues that can be used as food, its main component being skeletal muscle with some degree of fat and connective tissue. Since the early 1980s, the production, consumption and world trade of meat has increased considerably and these changes are related to world population growth, urbanization and rising domestic incomes in developing countries, as well as changes in consumption patterns, which trigger a global increase in demand for food of animal origin. In general terms, "quality" can be defined as the extent to which a product or service meets consumer expectations over time. When referred to meat quality, it focuses on hygienic aspects during its production, to its nutritional value or to the organoleptic or technological characteristics. The conservation of food implies the action to keep it with the properties or desired nature for as long as possible. The application of cold in meat, as the most used method for its conservation, is mainly due to two purposes: to preserve the initial food quality, with a view to its consumption, and to keep it at an adequate temperature for its maturation and the chemical and biochemical reactions that determine its quality and shelf life. The shelf life of food can be defined as the maximum time in which food maintains its nutritional, sensory, microbiological and safety qualities at levels accepted by consumers. Refrigeration and freezing are the most used traditional methods to preserve meat, based on the application of cold to the carcasses. The main objective is to avoid decomposition due to bacterial alteration. HIGHLIGHTS a. The use of antifreeze proteins reduces the size of ice crystals. b. Chilling causes weight losses in carcasses due to evaporation of water on the surface. c. Meat quality is due to pH, color, texture, WRC and chemical composition.
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... Regarding Ni concentration, the concentrated and diluted fractions of the SFC showed a similar distribution of the Ni in the two fractions, however, the concentration of the concentrate in the SFC-S2 was 0.313 mg/L and was higher than the concentrate of the PFC-S2. This could be justified by the formation of the ice in both methods, as the principle of the SFC require a formation of the ice nucleation inside the mother solution [47], which facilitates the migration of the ions of the heavy metals from the formed ice to concentrate during the separation. The Ni content in the concentrates of the second stage of PFC and SFC are equivalent to 4.138 mg/Kg 8.972 mg/Kg TS in the PFC-S2 and SFC-S2, respectively. ...
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... Understanding the freezing process is important for life sciences, 1-3 nanochemistry, 4,5 different natural, 6-10 biotechnological [11][12][13][14][15][16][17] and industrial [18][19][20] processes. Common to all these scopes is a freeze-induced phase separation (FIPS) into ice and a freeze-concentrated solution (FCS). ...
... Common to all these scopes is a freeze-induced phase separation (FIPS) into ice and a freeze-concentrated solution (FCS). 10,12,[21][22][23][24] IM/FCS morphology and the phase state of FCS determine the properties of frozen solutions 12,[25][26][27] and, consequently, the properties of freezedried/lyophilized products, [11][12][13][14][15] glaciers, 8,28 sea ice, 9,29 ice clouds 10 etc. Unlike bulk solutions, which freeze at the liquidus, [30][31][32][33] millimeter-scaled drops can be supercooled below the eutectic solidus. 34 Depending on solute molecular structure, several freezing 6,10,34,35 and glass transition 12,35 events occur upon cooling. ...
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... The application of -20 * -30°C freezing temperature might not be low enough to reach 'fast' freezing for larger samples. For instance, in food industry, fast freezing of blueberries using liquid nitrogen keeps the original microstructure of the product, but static freezing at -18°C results in significant damage [36]. Given the considerably greater sample size of soil than blueberry, it requires even lower temperature at the boundary and hence faster freezing, if the microfabric is to be kept intact. ...
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A systematical testing program on frozen Onsøy clay under isotropic loading and undrained shearing at different temperatures (− 3 ~ − 10 °C), strain rates (0.2~5%/h) and initial Terzaghi effective stress (20~400 kPa) was conducted with the focus on pore pressure development. It is meant to increase the understanding and facilitate the development of an ‘effective stress’-based model for multi-physical analysis for frozen soils. This study adopted the pore pressure measurement method suggested by Arenson and Springman (Can Geotech J 42 (2):412–430, 2005. https://doi.org/10.1139/t04-111) and developed a new testing procedure for frozen soils, including a ‘slow’ freezing method for sample preparation and post-freezing consolidation for securing hydraulic pressure equilibrium. The B-value of frozen soils is less than 1 and significantly dependent on temperature and loading history. The dilative tendency or pore pressure development in an undrained shearing condition is found to be dependent on both unfrozen water content and mean stress, which is consistent with unfrozen soils. Besides, the experimental results reported in the literature regarding uniaxial tests show that the shear strength does not share the same temperature- and salinity-dependency for different frozen soil types. The rate dependency of frozen soils is characterized between rate dependency of pure ice and that of the unfrozen soil and is therefore highly determined by the content of ice and the viscous behavior of ice (through temperature dependency). This paper also explains the pore pressure response in freezing and thawing is dependent on volumetric evolution of soil skeleton.
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... These losses are similar to those observed by Jha et al. (2019) and Bilbao-Sainz et al. (2020) in thawed potato and they can be attributed to the ice crystals formed during freezing. Thus, it is widely recognized that ice crystals produce mechanical damage on cell structures and the larger the size of the ice crystals, the larger the damage and, consequently, the larger the exudates after thawing (Li et al., 2018;Petzold and Aguilera, 2009). Data in Fig. 5 reveal that the application of SMFs during freezing, whichever the field intensity, did not significantly affect drip losses observed in potato after thawing (F (2,33) = 1.604, p-value = 0.216, n = 36) and, thus, mean DL values were similar in C, SMF dmax _40, and SMF dmin _150 samples. ...
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The effectiveness of static magnetic fields (SMFs) in improving food freezing is a topic that, nowadays, raises substantial controversy among the scientific community. To shed light on this matter, new freezing experiments, under well controlled conditions, were performed in potato samples subjected or not to SMFs of either 40-55 mT or 150-200 mT, that is, approximately 1000 and 5000 times greater than the Earth’s magnetic field, respectively. Our results showed that these SMFs did not affect supercooling, freezing kinetics, or potato quality. Thus, the supercooling reached before nucleation, the duration of the precooling, phase change, and tempering steps, the characteristic and total freezing times, drip losses, texture, and color were similar in potato samples frozen with or without SMF application. More experiments, at higher SMF intensities and in foods of different composition, should be performed to definitively evaluate the effectiveness of SMFs in improving food freezing.
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... During frozen storage, ice crystals will destroy muscle cells, resulting in mechanical damage and quality decline of muscle tissue (Petzold and Aguilera 2009). Therefore, the quantity, volume and distribution of ice crystals in frozen products will affect the quality of products. ...
... Figure 2(B)(c) shows that cryopreservation is mainly related to the formation of ice crystals in cells. The formation, size distribution and microstructure of ice crystals have been studied qualitatively and quantitatively by visualization techniques (Chow et al. 2005;Petzold and Aguilera 2009). The cryomicroscope can be used to observe the morphology of ice crystals and analyze the size, number and location of ice crystals. ...
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Frozen storage is one of the main storage methods for meat products. Freezing and thawing processes are important factors affecting the quality of stored foods. Deterioration of texture, denaturation of protein, decline of water holding capacity etc. are among the major quality issues during freezing that must be addressed. A number of advanced technologies are now available to detect the quality changes that can occur during freezing and/or thawing. This paper presents an overview of the techniques commonly used for the detection of meat product quality; these include: advanced microscopy, molecular sensory science and technology, nuclear magnetic resonance, hyperspectral technology, near infrared spectroscopy, Raman spectroscopy etc. These direct and indirect measurement techniques can characterize the quality of meat product from many different angles. The objective of this review is to provide an in-depth understanding of possible quality changes in meat products during freezing and thawing cycle so as to improve the quality of frozen and thawed meat products in industrial practice.