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Ice crystal growth of water and its aqueous solution is the key phenomenon in food freezing. In this research, the effect of static magnetic field (SMF) on single ice crystal growth was investigated combing experiment and simulation. The ice crystal growth of water and NaCl-water solution under 0 - 15 mT SMF intensities were studied. The UV absorbance of water after SMF treatment was measured. Phase field model was adopted to simulate the ice crystal growth. The results show that SMF significantly inhibited the growth rate, while had little effect on the morphology and growth direction of ice crystals. SMF had a certain enhancement effect on the UV absorbance of deionized water. The proposed model could well simulate the ice crystal growth under different SMF intensities. Combining experimental and simulation results, it can be inferred that SMF inhibits ice crystal growth by enhancing original hydrogen bonds and reducing free energy. [ABSTRACT FROM AUTHOR]

In this study, a cabin design was made for fast freezing in household refrigerators using different fan types (radial fan velocity of 1100, 1500 and 1900 rpm) and axial (1350 rpm) and the effects on the quality characteristics of beef were examined. Before the freezing process, the beef (Semitendinosus) was sized at 10 × 10 × 2 cm as a single fillet; 2 × 2 × 2 cm as the cubed sample and the minced beef was prepared by the butcher from the same meat and shaped with the dimensions of 10 × 10 × 2 cm. It was seen that when the fan velocity was 1900 rpm during the freezing process, the weight (0.39–11.61 %) and cooking loss (26.69–44.66 %) values of the beef samples decreased. A decrease was observed in the TBARS values (0.34–0.87) of the sample as the radial fan velocity increased in radial fan. When the total color change values (3.96–7.59) of all beef samples were examined, it was seen that the least color change was achieved with the axial fan before and after cooking. When the textural properties of the meat were examined before and after cooking, it was observed that the hardness decreased as the radial fan velocity increased, and the lowest hardness value was obtained from freezing with the axial fan. In addition, porosity values decreased and protein denaturation temperatures increased due to the formation of smaller ice crystals with the axial fan. As a result, it has been observed that fan type and velocity have significant effects on accelerating the freezing process and preserving the quality of beef samples. [ABSTRACT FROM AUTHOR]

Atlantic salmon (Salmo salar) is the top imported fish in Japan. It is usually shipped in chilled form by air cargo to preserve its freshness but posts a high environmental impact. As a sustainable alternative, ocean freight can be implemented if the salmon is frozen. However, the question arises as to whether the quality of the frozen and thawed salmon is comparable. Therefore, the aim of this study is to evaluate the environmental impact and quality of Norwegian Atlantic salmon in chilled and frozen form. The CO 2 equivalent emissions of the key life-cycle stages were calculated, and the quality assessment was carried out by colorimetry and sensory evaluation with careful preparation and execution. The results showed that the CO 2 equivalent emissions of the packaging, transport, and overall cycle of the frozen salmon were 35 %, 90 %, and 60 % lower than those of the chilled salmon. Color measurements using digital imaging show that the frozen salmon is slightly redder, with a higher a* value and a lower b* value. Panelist ratings indicated that there was no statistically significant difference in perceived color, glossiness, fishy smell, texture, umami, and juiciness between chilled and frozen salmon. The study provides preliminary results that demonstrate the potential of frozen seafood and ocean freight transportation as a sustainable cold chain solution. [ABSTRACT FROM AUTHOR]

We present a mathematical model that considers the formation of an ice layer with expansion in a container with a moving boundary. The displacement represents the strain of the tank when the solidifying water expands. The results show that the ice and liquid fractions inside the tank depend on the spring constant and dimensions of the tank. If the spring constant tends to infinity, the ice and liquid fractions are those corresponding to an isochoric process. For each temperature, there is a threshold value of the spring constant, below which all the contents of the tank become ice and above which a smaller fraction does so. The threshold value of the spring constant relates to the degree to which water expands as it freezes. Structural design of a tank shows that the process departs from isochoric. Keeping the process completely isochoric requires oversizing the tank with corresponding increases in manufacturing costs and transportation weight. • We model formation of ice in a self pressurizing elastic tank for freezing temperatures. • The model calculates ice fraction as a function of freezing temperature and elastic constant. • The solution includes as a special case the isochoric freezing process. • The model determines the modified spring constant below which all the water becomes ice. • Structural design of a spherical tank shows the process may depart from the isochoric case. [ABSTRACT FROM AUTHOR]

• Almost all the investigated PCMs are compatible with aluminium, copper, stainless steel, and plastic. • Differences in thermal behaviour were observed despite the same operating conditions were applied. • The thermophysical and transport properties deeply affect the thermal performance of PCMs. • The charging time differs from the discharging one despite the same operating conditions. • The presence of metal lattice structures reduces the charging time more than the discharging one. Refrigeration, air conditioning and heat pump sector represents between 25 and 30% of the global consumption of electricity and this figure is expected to rapidly grow due to the current trend of electrification. To increase the efficiency of these systems or to maximize the use of renewable energy, latent thermal storage systems are being studied and recommended. However, there is a lack of reliable design rules based on trustable data that could help the thermal experts to design efficient and cost-effective latent thermal energy storage. This paper follows a previous work recently published (Longo et al., 2022) where the thermo-physical and transport properties of a few low temperature PCMs (i.e. 2–9 °C of melting temperature) were measured and discussed. In the present work, the attention is focused on two other fundamental aspects: the PCMs' compatibility with the most common construction materials and their thermal behaviour during the solid/liquid phase change. The collected results will contribute to add currently unavailable data in the literature and to highlight interesting insights on the performance of the selected PCMs. [Display omitted] [ABSTRACT FROM AUTHOR]

Ultrasonic-assisted freezing has received much attention for its outstanding capability to improve freezing performance. However, most researchers focus only on single-frequency ultrasound, lacking research on dual-frequency or multi-frequency ultrasound. Based on the relevant theory of the promotion of solution crystallization by ultrasound wave, this paper experimentally studied the subcooling degree and time of water freezing under the action of ultrasound. The experimental study was carried out on the production of ice from water by using different ultrasonic waves under a specific power. The results show that the effect of ultrasound with specific frequency combinations can improve the speed of water freezing and reduce the subcooling degree. When the experimental conditions are 28+33 kHz and 60 W, the comprehensive performance is the best. Compared with the condition without ultrasound, the subcooling degree is reduced by 5.28 K, and the time required for the complete solidification of water into ice was reduced by a duration of 60 s. [ABSTRACT FROM AUTHOR]

• Effects of SMF on four kinds of foods were compared from micro and macro scales. • SMF tended to decrease the ice crystals size for four kinds of fruits and vegetables. • Higher SMF intensity did not always produce smaller ice crystals. • Significant effect of SMF on macro-scale quality only appeared in one kind of food. Novel food freezing technology assisted by static magnetic field (SMF) has emerged in recent years. However, few papers have compared the effects of SMF on different kinds of foods under the same experimental conditions. This study investigated the effects of 0 to 45 mT SMF intensities on apple, peach, cucumber and Indian jujube from micro and macro scales. The parameters including ice crystal size, time through -1 ∼ -5 °C, drip loss and texture were compared. The results show that SMF tended to decrease the ice crystals size for four kinds of fruits and vegetables, and the optimal SMF intensity varied with the types of foods. The beneficial effect of SMF on reducing ice crystal size did not always appear in macro-scale freezing. Positive effects of SMF on macro-scale parameters only appeared in Indian jujube, and stronger intensity brought better quality. [ABSTRACT FROM AUTHOR]

In this study, a series of experiments were conducted to comprehensively investigate the freezing process of a static supercooled horizontal water bridge between cold fins. How cold surface temperatures, water bridge volumes, and air relative humidities with a wide range of variation effects on water bridge freezing were further explored. The dynamic evolutions of internal temperature, ice-water interface, and freezing time were revealed. Some particular deformation phenomena, such as ice rings and protruding droplets, were observed during the freezing process of the water bridge. The results indicate stable nucleation temperatures in the recalescence stage. It was found that whether nucleation and crystal growth occur depends on the nuclear energy barrier, and whether the nucleation temperature changes when nucleation occurs is determined by the stable nucleation temperatures. When the cold surface temperature is constant, the nucleation temperature decreases with the increase of water bridge volume and air relative humidity, respectively. Compared with water bridge volume, cold surface temperature and air relative humidity have a more significant effect on water bridge freezing. Furthermore, the lower the cold surface temperature, water bridge volume, and air relative humidity, respectively, the shorter the freezing time and the faster the movement velocity of the ice-water interface. In addition, a semi-empirical correlation is proposed to predict the movement distance of the ice-water interface, which can accurately predict 95% of the considered experimental data with a deviation of ±25%. [ABSTRACT FROM AUTHOR]

Pomegranate juice quality depends essentially on its chemical and nutritional components stability. The valuable nutritional components may be reduced during its processing or storage. This study examined the effect of pomegranate arils’ frozen storage on juice quality, in terms of physicochemical properties and bioactive compounds stability. The physicochemical criteria (pH, TSS, TA, color attributes) and biochemical criteria (Total Phenolic content, Total anthocyanin content and antioxidant activity) were assessed on pomegranate juice extracted from frozen arils stored at (-18°C) for 6 months. Two cultivars ‘Sefri’ and ‘Wonderful’ were subject to this study. Results showed that the pH, TSS, and TA were generally stable in frozen arils juice. However, arils freezing had a significant effect on pomegranate juice color parameters. In fact, a significant decrease of a* values were revealed in juice samples for both cultivars. Therefore, the color intensity (chroma) has decreased significantly and total color differences (ΔE∗ab) also showed a significant difference (p < 0.05) between fresh juice and frozen arils juice. Arils freezing conditions (−18 °C) for 6 months didn’t affect pomegranate juice physiochemical criteria. However, bioactive compounds of pomegranate juice were reduced significantly. In fact, total phenolic content decreased by about 27% and 31% for ‘Sefri’ and ‘Wonderful’ cultivars, respectively. Total anthocyanins content decreased by 20% and 30% for ‘Sefri’ and ‘Wonderful’ cultivars, respectively. Antioxidant activity, measured based on the juice’s radical scavenging properties using the 2,2-diphenyl-1-picrylhydrazyl method, decreased by about 50% for ‘Sefri’ cultivar and 60% for ‘Wonderful’ cultivar.

The objective of this study was to investigate the effect of microwave-assisted freezing (MAF) on some quality attributes of lamb meat. The lamb meat was frozen under microwave irradiation with different power levels of 0%, 40%, 50%, and 60%. The microstructure of frozen lamb meat was investigated immediately after freezing by light microscopy technique. Also, the quality properties such as drip loss, texture, and color were assessed after thawing of frozen meat samples. Results showed that the average size of ice crystals at the highest level of microwave power was approximately 38% lower than the frozen sample without the application of microwave irradiation (control sample). drip loss and color change decreased by increasing the power level of microwave irradiation. Also, MAF at the power levels of 50% and 60% improved the hardness of thawed lamb meat. [ABSTRACT FROM AUTHOR]

• The effects of SMF were compared under -18 °C and -40 °C freezing. • SMF reduced the maximum ice crystals formation time under -40 °C freezing. • The total weight loss of samples had a significant reduction after SMF was applied. • The pH was closer to the fresh samples under some SMF intensities. • SMF had more obvious beneficial effect on improving texture under -18 °C freezing. The effect of magnetic field on quality changes of frozen channel catfish under two different freezing temperatures was investigated in this paper. During the freezing process of channel catfish under -18 °C and -40 °C, which represented slow freezing and fast freezing conditions, static magnetic field (SMF) intensities of 0, 1.7, 3.5, 7.0 and 10.7 mT were applied. The temperature was monitored during the freezing process, and parameters of weight loss, pH, and textural properties were measured and compared. The results show that for the freezing condition of -40 °C, the time spent at the maximum ice crystals formation stage was significantly reduced after the application of SMF. The total weight loss of SMF samples frozen at both freezing temperatures had a significant reduction. The pH was closer to the fresh samples after 7.0 - 10.7 mT and 10.7 mT SMF intensities were applied to -18 °C and -40 °C, respectively. SMF had a beneficial effect on improving the hardness and chewiness properties of frozen fish, while it was only obvious at -18 °C freezing condition. [ABSTRACT FROM AUTHOR]

• Effects of PEF and OMF on supercooling of beef steaks were explored. • Lean beef's supercooled state was maintained with the PEF treatment. • Fat caused the non-uniform current density and temperature distribution under PEF. • Combined PEF and OMF were required to inhibit ice nucleation within fat-rich beef. • Quality factors indicated that supercooling could prolong the shelf-life of meat. Supercooling is of particular interest in the food industry since it has a great potential to improve shelf-life without freezing damage during storage. Food is a complex matrix of multi-components and its supercooling behavior may depend upon the physical properties of each component. In this study, the effect of a pulsed electric field (PEF) and an oscillating magnetic field (OMF) on supercooling of beef at different fat levels were explored. Lean-rich beef was supercooled with PEF only, while the simultaneous application of PEF and OMF was required for fat-rich beef. The finite element method (FEM) simulation demonstrated that fat caused the non-uniform current flow and temperature gradient due to the low electrical conductivity, and subsequently negative impacts on the supercooling extension of fat-rich beef meat. The OMF combined with PEF ensured maintaining a supercooled state of fat-rich beef at −4 °C by synergistically inhibiting ice nucleation. The beef steaks preserved in the supercooled state showed significantly lower drip loss, compared to the conventionally stored controls, and there were no significant differences in color between supercooled and fresh steaks during the 7 day-preservation. [ABSTRACT FROM AUTHOR]

The finite difference method (FDM) was used to calculate the temperature profile of the slab T (x,t) and freezing time (t calc). The methodology is based on the integral average property (P av) for each property P(T) (k, ρ , and Cp ap), which is the integral of P(T) from the initial slab temperature (T 0) up to a reference temperature (T ref), divided by the temperature range (T ref – T 0). The objective is to obtain an adequate (T ref) and a set of appropriate P(T) for a given set of experimental data. Simulations were performed to test several (T ref), obtaining (t calc), which was compared with 337 data from the slab freezing process. The principal findings were used to obtain the following parameters: minimum error E min = -6.71 %, overall mean error E mean = -0.27 %, maximum error E max = 5.84 %, and standard deviation σ n-1 = 1.69 %. When the Biot number is large, Bi f → ∞, T ref = T arith or T ref = T(i) is generally adequate to calculate (t calc), (T arith) being the average arithmetic temperature and T(i) temperature at a point (i), respectively. If Bi f → 0, T ref = T cf generally produces good results for (t calc), (T cf) being the final temperature in the center of the slab. If the traditional Biot number Bi → 0, the average temperature (T av) → (T c), obtained from the analytical solution with the convective boundary condition for a slab, (T c) being the center temperature. If Bi → ∞, (T av) → (T a) + (2/π)(T c - T a), (T a) being the ambient temperature. [ABSTRACT FROM AUTHOR]

• The first CFD freezing model using CT images to generate a realistic model geometry. • Temperature-dependent thermal properties of chicken meat were employed. • Mean error between measured and simulated average temperatures was less than 1.3 °C. • The effect of operating conditions on freezing time was modelled. This study presents a 3D computational fluid dynamics (CFD) model to predict the temperature profile of bulk-packed whole chickens during forced-air freezing based on 3D computed tomography (CT) images of the chicken. The model was validated against experimental cooling data. By using the temperature-dependent thermal properties of chicken meat, the mean differences between the predicted average drumstick temperatures with corresponding experimental results were less than 1.3 °C for all tested conditions. Based on the validated model, a correlation was proposed to estimate the effect of operating conditions on freezing time and that correlation may be used to optimise the design of the freezing tunnel for chicken products. [ABSTRACT FROM AUTHOR]

• Experimental freezing trials of packed chicken drumsticks were performed. • A numerical model for the freezing drumsticks was developed and validated. • Drumstick packing arrangement did not have a significant effect on freezing rate. • The presence of a liner bag increased freezing time by more than a factor of three. The cooling of polylined bulk-packed drumsticks during forced-air freezing was examined experimentally and numerically. The experiments showed that, when contained within the liner bag, the packing arrangement of the chicken drumsticks within the tray did not have a significant impact on freezing rate. However, the presence of the liner bag had a significant impact on freezing times, increasing them by more than a factor of three. A 3D computational fluid dynamics (CFD) model to predict the temperature profile of bulk-packed drumsticks, based on 3D computed tomography images of the chicken, was also developed and validated against the experimental cooling data. By using temperature-dependent thermal properties of chicken meat, the mean differences between the predicted average drumstick temperatures and corresponding experimental results were less than 1.1°C for all tested conditions. Based on the validated model, a correlation was proposed to estimate the effect of operating conditions on freezing time and that correlation may be used to optimise the design of the freezing tunnel for chicken products. [ABSTRACT FROM AUTHOR]

• Raw saury meat of frozen-thawed and non-frozen were compared in consumer preference. • Consumer panel sensory evaluation by 103 panellists was executed with extreme care. • Consumer preference was not significantly varied between frozen and non-frozen. • Linguistic information 'frozen' drastically reduced the consumer preference. • Influence of the information 'frozen' was inferred based on statistical analysis. Freezing preservation is the only technique that has potential to preserve food as it is even for years. It can also bring us important benefits such as; stable food supply, saving energy, reducing environmental load, food loss and parasites risk. However, many consumers are suspected to have prejudice "frozen food does not taste good" that might be the biggest obstacle to the further utilisation of frozen preservation, especially for the fishery food consumed in raw as sushi or sashimi. Therefore, sensory evaluation of sashimi made of Pacific saury was attempted to investigate whether the consumer preference of frozen-thawed fish is apparently worse than non-frozen fish. The influence of linguistic information 'frozen' on the consumer preference was also investigated. Pair test was conducted to compare non-frozen sample and frozen sample. The test was executed twice where 1st test was made without any information and 2nd test was made with disclosing whether the sample was non-frozen or frozen. To execute consumer panel sensory evaluation of sashimi, extremely careful preparations were applied for whole process from harvest to serving to ensure the consistent quality of all pieces of sashimi, by cooperation with a fish supplier and a chef training college. As a result, it was confirmed the average score of the preference was almost same regardless of frozen/non-frozen under the blind condition. However, by disclosing the information frozen/non-frozen, the score for frozen-thawed saury drastically decreased. Factor analysis was further executed to discuss the reason why the information 'frozen' decreased the consumer preferences. [ABSTRACT FROM AUTHOR]

In the frame of African artisanal small-scale extraction of palm oil, the effects of post-harvest storage time and freezing of palm fruits on the extraction yield and quality of crude palm oil (CPO) were studied at laboratory scale using a process mimicking artisanal extraction. The extraction yield and free fatty acid (FFA) content of CPO increased with the length of fruit storage time at room temperature and freezing. FFA, total fatty acid and triacylglycerol profiles indicated a lack of specificity of the lipases at work. During post-harvest storage, the carotenoid content of CPO decreased slightly, tocopherols and tocotrienols (tocols) remained steady, while lipid oxidation remained at a very low level. For frozen fruits, carotene and tocol contents decreased sharply as a function of storage time, thought remaining quite high, but decreasing amounts of secondary oxidation products were detected. The FFA content and lipid oxidation level were highly correlated, indicating a pro-oxidant effect of FFAs. To conclude, three days of storage prior to artisanal extraction seemed the best trade-off between extraction yield and CPO quality. Combined storage at room temperature and freezing of palm fruits led to a large range of FFA contents in CPO. Optimization of the FFA contents of artisanal CPOs in line with local consumer's demand calls for an assessment of their functional properties and sensory perception of foods formulated with CPOs. [ABSTRACT FROM AUTHOR]

• Carbon dioxide was infused into model solid food (gelatin gel). • Infusion of CO 2 (ICO) in gelatin gel samples facilitated nucleation to occur. • ICO sample nucleated at temperature closer to ultrasound application with shorter delay. • ICO treatment was in favor of ultrasound-initiated nucleation. To understand the mechanism of ice nucleation induced by ultrasound in solid food matrix, the effect of infusion of CO 2 (ICO) in a model solid food system (gelatin gel) on the dynamic nucleation of ice during ultrasound-assisted immersion freezing (UIF) was investigated. The results showed that the content of absorbed CO 2 in a gelatin gel samples increased with ICO-treated time increase and a great number of micro bubbles were observed in the samples by light microscope. The nucleation temperatures of the samples with/without ICO treatment increased by the application of ultrasound. In addition, there was a better correlation between the nucleation temperature and the ultrasound onset temperature for the samples infused with CO 2. Moreover, compared to the samples without ICO treatment, the nucleation delay was shorter and nucleation temperature was closer to ultrasound irradiation temperature. It can be concluded that cavitation and ultrasonic irradiation parameters are factors affecting the nucleation of model solid food and CO 2 infusion can be used to initiate the nucleation of solid samples during UIF. [ABSTRACT FROM AUTHOR]

• A hydrofluidisation freezing test rig was designed and experimentally investigated. • PIV measurements of the coolant flow inside the hydrofluidisation chamber were done. • Experiments were performed for various sample positions and coolant mass flow rates. • Velocity of the coolant along the sample walls varied within a sample position. • Mass flow rate increase had a minor effect on the boundary layer separation angle. Hydrofluidisation freezing is a novel and promising food processing technology. This freezing method offers a high product quality, mostly due to the short process times resulting from high heat transfer coefficients. Consequently, hydrofluidisation freezing time is relatively short. Nevertheless, comprehensive experimental studies of this method are not available in the current literature. Therefore, the scope of this study was to experimentally investigate the fluid flow inside a hydrofluidisation chamber. The construction of the test rig used for the presented analysis enabled particle image velocimetry (PIV) measurements of the process. The PIV method was used for velocity field measurements. These measurements were conducted for various mass flow rates of the coolant and for various ratios of the distance between the sample and the orifice (H) to the orifice diameter (d). The results showed that the H/d ratio has a strong influence on the velocity of the fluid near the sample walls. The velocity of the fluid rapidly decreased for H/d higher than 14.0. Moreover, the increase of the mass flow rate and, in consequence, the coolant Reynolds number for H/d exceeding 14.0 did not affect significantly the velocity field around the analysed sample. Hence, the gathered results showed the importance of the correct design of the HF chamber in order to maximise the fluid flow velocity around the processed objects. Moreover, various velocity profiles were analysed showing the velocity variation under the sample. The collected velocity profiles and velocity fields were considered suitable for the hydrofluidisation freezing CFD models validation. [ABSTRACT FROM AUTHOR]

• Supercooling freezing was applied to firm tofu that is the typical protein coagulum. • Effect of freezing rate after releasing from supercooling was evaluated. • Influence of frozen storage up to one month was examined. • Quality changes during supercooling freezing and storage was investigated in comparison to conventional freezing. This article attempted to apply supercooling freezing under atmospheric pressure to minimize the freezing damage on firm (momen) tofu, which is a representative of agglomeration type protein coagulum. Especially, we focused on the influence of different freezing rate after the releasing from supercooling state. Storage test up to one month with different storage temperature was also carried out. The quality parameters such as drip loss, texture, and microstructure were analyzed and compared with conventional methods (slow freezing and rapid freezing) after the storage under −80°C and -20°C up to one month. As the results, significant advantages were confirmed on the sample prepared by supercooling freezing even after the one-month storage. Further, higher freezing rate after the releasing from supercooling states successfully reduced the drip loss and kept good texture, with less microstructural damage. The possible mechanism on which supercooling freezing affects ice crystals formation and quality degradation are thoroughly discussed. [ABSTRACT FROM AUTHOR]

Children conceived by assisted reproductive technologies (ART) have an increased risk of adverse effects and diseases. It is still unresolved whether the ART procedures or infertility/subfertility status of the parents might explained some of these changes. The hypothesis is that ART procedures themselves can induce adverse epigenetic effects, especially because they take place at times when maximal epigenetic reprogramming is occurring, including during female gametogenesis and after fertilization. In this manuscript we will present the main results of the studies assessing the epigenetic impact after oocyte vitrification. [ABSTRACT FROM AUTHOR]

• A laboratory scale freezer was developed and offers uniform freezing conditions. • Tylose dehydration due to freezing was studied for mechanical and cryogenic freezing. • Repeatable results of weight loss and temperature measurements were obtained. • Relation between weight loss and surface temperature during freezing is illustrated. The freezing of unpackaged foods induces water loss due to interactions with the surrounding medium. The weight loss resulting from this dehydration is up to 6% according to the product and the freezing process. Food dehydration was studied for various operating conditions from mechanical to cryogenic ones with the same freezing device using Tylose as a food model material. The dehydration was studied for several surface states (smooth or streaked surface) and product porosities (full or perforated plates). It was found that weight loss is estimated with a good reproducibility in the developed freezer. The influence of freezing operating conditions and product characteristics on weight loss were clearly pointed out. From these results, weight loss could be related to the surface temperature evolution. In any case, these results confirm that to limit the weight loss, it is essential to decrease as quickly as possible the surface temperature of the product. [ABSTRACT FROM AUTHOR]

Highlights • The effect of static electric field was investigated on the freezing parameters of some food systems. • The electro-freezing showed a significant effect on freezing parameters of all samples. • An optimum strength exists for the best conditions of freezing under static electric field. • Static electric field assisted freezing increased the nucleation temperature and phase transition period. Abstract In present study the effect of freezing in the absence and presence of static electric field (SEF) on selected freezing parameters of liquid and solid food including: distilled water, NaCl solutions, mushroom extract and mushroom were investigated. The static electric field was applied at the intensities of 0.0–9.6 × 105 V/m during freezing at -30 ± 1°C. The freezing parameters of different samples were evaluated from the freezing curve of them. Results showed that among the different samples, the pure water had the highest freezing temperature, supercooling degree and shortest phase transition period in the absence of electric field. By applying the electric field, the nucleation temperature and phase transition period of the samples increased. The highest nucleation temperature was observed in the pure water under 6.4 × 105 V/m electric field. The nucleation temperature of the other samples showed an optimum value in the intensity of 3.2 × 105 V/m. [ABSTRACT FROM AUTHOR]

Highlights • Cold thermal storage is used to store energy during off-peak load for later use. • Ice storage is the most effective method for storing energy. • The mechanics of ice formation on flooded tubes in power plant AC is introduced. • Cold thermal storage application presented as best choice for reducing peak loads. Abstract Energy storage systems provide the methods and technologies used to store energy of various forms. Cold thermal storage is used to store energy during off-peak load conditions for later use during peak load conditions. A flooded tube for cold thermal storage was built to study the formation of ice experimentally. The flooded tube was subjected to stagnant water, stirred water, and recirculated water. The flooded tube with recirculated water showed the best performance. About 7.9 g/m2 s of ice was formed with a starting overall heat transfer coefficient of 1096 W/m2 K. Discharge cycles were analyzed, and it was determined that 7.1 kg of ice was sufficient to hold a load for 110 min for a 927 W unit. [ABSTRACT FROM AUTHOR]

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Highlights • Quality changes in apple tissue were studied during frozen storage. • Temperature fluctuations significantly affect the apple quality during storage. • The quality data were fitted to first order kinetics. • A developed kinetic model can be used to predict the apple quality evolution. Abstract Apple quality after freezing is affected by temperature fluctuations during cold storage. Ice re-crystallization and sublimation occur slowly at a constant temperature over a long period of storage, and more rapidly during fluctuating temperatures. These phenomena impact fruit quality, thus reducing storage life. To this end, apple tissue samples were frozen and subsequently stored in three different freezers set at −12 ± 3 °C, −18 ± 3 °C, and −23 ± 3°C. In each freezer, three different compartments were created to achieve different amplitudes of temperature fluctuations: (i) low (± 0.1 °C), (ii) medium (± 0.5 °C) and (iii) large (± 1.8 °C). Frost formation, drip loss, color changes and vitamin C (ascorbic acid) content were measured during five months of storage. The results revealed that apple quality was strongly affected by the temperature fluctuations during frozen storage. The kinetic models were calibrated using apple quality data collected at low and large amplitudes of fluctuations. The temperature dependency was successfully incorporated using an Arrhenius equation that integrates the temperature fluctuations. The kinetic models were validated using apple quality data gathered at a medium amplitude of fluctuation. In addition to a kinetic model, a physical model was applied to predict frost formation. [ABSTRACT FROM AUTHOR]

Hairtail samples were frozen by three different treatments, including conventional air freezing (CAF) at −20  o C, refrigerator cryogenic freezing (RCF) at −80  o C and liquid nitrogen immersion freezing (LIF) at −196  o C. In order to investigate the influence of freezing treatments on the development of ice crystal in hairtail samples, an improved method based on cryosection was applied to observe the formation of ice crystals in frozen hairtail meat, comparing with the traditional method of cryosubstitution. Results showed that cryosectioning was a highly effective tool for intuitionistic view of ice crystals, and greatly shortened the time from 3–5 days to 20–30 min. The equivalent diameter of the ice crystals determined by cryosectioning were 12.6 ± 3.73, 3.62 ± 1.91, and 1.22 ± 0.39 µm for the samples subjected to CAF, RCF and LIF, respectively. Smaller and more regular intracellular ice crystals were observed in hairtail samples frozen by LIF compared with other treatments. The microstructure of three frozen treated samples was profiled by scanning electron microscopy as well. Significant differences were observed in the water holding capacity in frozen samples of CAF (86.8%), RCF (87.4%), and LIF (89.2%). The characteristics of ice crystals, which have a strong influence on the final quality of the food, were considered as an important factor for the quality of hairtail during freezing. [ABSTRACT FROM AUTHOR]

This study aimed to model an innovative process of pulsed microwave assisted freezing (MAF), which was expected to improve frozen product quality. The phase change model was based on spherical ice crystal growth and an original enthalpy formulation. The objective was to understand better the thermal interactions between microwaves and a product being frozen in a TE10 waveguide in which nitrogen gas and microwaves reach the product on the top surface. The 2D model was validated against the literature data and used to perform numerical simulations. The freezing front location and the reflection at air-product interfaces have a large impact on microwave behaviour in the product, especially on hot-spot displacement. As in some experimental works, temperature oscillations were observed. It is shown that their amplitude is related to the pulse duration. These results will help in designing experimental procedures to study the interest of using low energy pulsed microwaves during freezing. [ABSTRACT FROM AUTHOR]

Summary The aim of this study was to compare the MRI signal of the brachial plexus and surrounding muscles before and after freezing/thawing on a murine model. A first MRI going through the brachial plexuses of 5 healthy Wistar rats was performed immediately post-mortem. A second MRI was performed after freezing at –30 °C and then thawing at 20 °C for 24 hours. All MRI images were segmented to make nerve and muscular structures appear and calculate the average intensity of the MRI signal using the program ImageJ. The average nerve and muscular MRI signals were compared before and after freezing/thawing and rated in grayscale units between 0 and 255. The average intensity of the MRI signal of nerve structures was 40.315 grayscale units before freezing and 31.943 after freezing/thawing. The average intensity of the MRI signal of muscular structures was 25.44 grayscale units before freezing and 35.710 after freezing/thawing. Our results have shown that the intensity of the MRI signal of the brachial plexus was higher before freezing/thawing. The intensity of the MRI signal of muscles was lower than the intensity of the brachial plexus before freezing/thawing and higher after freezing/thawing in muscles than in brachial plexus. The MRI could be used in clinical practice to monitor the reinnervation after frozen nerve allografts. [ABSTRACT FROM AUTHOR]

A one-dimensional mathematical model has been developed to solve the heat conduction equation and simulate the freezing process for a slab. The mathematical model was solved using finite differences and the method of lines (MOL). In MOL, spatial derivatives are discretized by finite differences, and the resulting system in time is integrated using an appropriate solver. Several sets of thermal properties were selected to simulate the process. Predicted freezing time values were compared to 142 published experimental data sets. Predictions obtained by published numerical methods were compared to the experimental data. The freezing time predictions of the proposed model give a percentage error in the range of −4.55 <  E (%) < 4.09, which includes the 142 data sets using the best calculation results. In summary, the MOL is a good numerical prediction method since an adequate set of thermophysical properties is especially tested and selected for each data set. [ABSTRACT FROM AUTHOR]

Scots pine ( Pinus silvestris L.) cone and seed water contents were analyzed in two consecutive seasons during maturation stage in the autumn and in January and March before seed dispersal. Cones with different water contents were subjected to 2 h of freezing at −30 °C, and seed viability and laboratory germination of seeds from individual cones after treatment were analyzed. Seed water content could be well predicted with the measurement of the cone water content, and the general relationship between these two could be described with a generalized logistic function. On average, the water content of cones was 5%-10% units higher than the seeds inside them. The higher the cone water content at the onset of freezing treatment, the higher the proportion of seeds with apparent damage (based on visual inspection of seeds using X-ray images) in that particular cone. High water content in cones also resulted in decreased germination after freezing treatment. The critical cone water content for 50% germination after freezing at −30 °C was approximately 31.3% (fresh mass basis). This corresponds to 21.6% water content in seeds. [ABSTRACT FROM AUTHOR]

From January 2001 to May 2002, 300 chicken carcasses from retail shops in Dakar were examined for prevalence of Salmonella and Campylobacter. Of these, 146 were fresh products, 58 were refrigerated and 96 were frozen. Salmonella was isolated from 96 (32%) of the carcasses analyzed. The most prominent Salmonella serovars were Salmonella Hadar (41.6%) and Salmonella Brancaster (20.8%). Campylobacter spp. was isolated from 168 (56%) of the samples. C. jejuni was more frequently isolated (59%) than C. coli (27%). The contamination rates for Campylobacter were significantly different in relation to the type of carcass: 76% for fresh, 53% for chilled and 28% for frozen.