Refrigeration Temperature Research Articles

Visual Performance of Fermented Whey with the Addition of Pectin and Chitosan During 24 Hours Storage at Refrigerator Temperature

Fermentation of whey often faces problems with the product clarity due to the milk solids residue from previous cheese making process. The aim of this research was to determine the clarity and the performance of fermented whey precipitation process in the presence of pectin and chitosan as coagulant. Whey was initially pasteurized and added with pectin and chitosan prior to fermentation with mixed starter culture. Fermented whey was stored in refrigerator for 24 hours. Data were obtained using visual analysis by 15 semi-trained panelists. Qualitative scorings were given by (+) or (-) markings from the specified criteria. The data were compiled in a table, showcasing the observed characteristics at the initial and final states of fermentation. The results showed that the highest clarity (+++) was achieved by the fermented whey with the addition of pectin, as well as most stable sediment performance (+++) was also produced by pectin treatment. However, while fermented whey with the addition of pectin exhibited clarity, the level of clarity achieved by fermented whey with the addition of chitosan was superior.

Enhancing the quality and shelf life of chevon using orange peel extract

The experiment was conducted to find out the effect of different levels of orange peel extract as a natural antioxidant and antimicrobial agent on fresh and preserved chevon. For this purpose, fresh chevon samples were divided into four treatment groups. These were treated as T0 (control group 0% orange peel extract), T1 (0.2% orange peel extract), T2 (0.3% orange peel extract) and T3 (0.4% orange peel extract) respectively. Sensory tests (color, flavor, tenderness, juiciness and overall acceptability), proximate components (DM, CP, EE and Ash), physicochemical quality (Raw meat pH, cooking loss), biochemical properties (POV, FFA and TBARS) and microbial assessment (TVC, TCC and TYMC) examination were determined in order to evaluate the effect of orange peel extract as natural antioxidant and antimicrobial agent for maintaining chevon qualities and the shelf-life of chevon for 0, 5, 10 and 15 days of storage period under refrigeration temperature. Among the four treatments T3 (0.4% orange peel extract) was the best in terms of nutrient quality, physicochemical properties, biochemical analysis and microbial assessment. Therefore, it is concluded that 0.4% orange peel extract may be used up to 15 days for chevon preservation.

Performance test of small fishing vessel refrigeration machine for fish storage

The refrigeration system in the fishing process is important for maintaining the quality of the catch. However, the design of small-scale refrigeration machines is still not common, so it is an interesting study. Therefore, this study aimed to evaluate the design of small-scale fishing vessel refrigeration machines. Field studies are needed in machine manufacturing to observe the components required to match the refrigeration machine components onboard fishing vessels. This uses a direct observation method to determine the components of the refrigeration machine on the ship. Furthermore, the performance of the machines produced will be tested through the load cooling process. Parameters determined in the performance test include monitoring temperature (suction and discharge), pressure (suction and discharge), evaporator temperature, load temperature, COP (Coefficient of Performance), and compressor power. Refrigerant temperature measurement uses an insulative principle so that ambient temperature does not affect it. The result is that the machine produced has a capacity of 35 l or 15 kg of load. Meanwhile, in the performance test, the COP and electrical power generated while cooling the load for approximately 4 hours were 2,42 and 507 W, respectively. The results of this design were successful and did not experience failure. The significanceof this study can be used as a reference source for making cooling machines for storing the catch of small-scale fishermen.

Dry LAMP: A point of care diagnostics for diagnosis of bovine tropical theileriosis.

Theileriosis is an important tick-bome hemoprotozoan disease of cattle which causes severe economic loss due to morbidity and mortality. A diagnostic test having high sensitivity, specificity and easy application at the field level is the need of the hour. In this regard Loop-mediated isothermal amplification (LAMP) is proven to be a sensitive, easy and time efficient method. One of the major obstacles for the application of LAMP is the difficulty in maintaining the cold chain to preserve reagents. Thus, the challenge is to develop a LAMP kit in a ready-to-use format with dried reagents useful for quick and simple application in field conditions. The optimized reaction of wet LAMP was followed for the standardization of dry LAMP with certain modifications which are needful. The major modification is vitrification technology of enzyme using trehalose. LAMP assay (dry and wet LAMP) was found to be more sensitive (100%) when compared to microscopy (69.5%) and PCR (86.9%). It was observed that the dry LAMP reaction tubes at room temperature as well as refrigeration temperature provided successful amplification till 7 weeks. The drying conditions of LAMP reagents were optimized, and finally managed to dry them in a single reaction tube without reducing the sensitivity. This technology enables us to transport LAMP kits to areas where the cold chain is not easily available.

PERBANDINGAN KADAR DAN UJI MUTU FISIK INJEKSI DEXAMETHASONE SODIUM PHOSPHATE SEBELUM DAN SESUDAH MASA KADALUARSA SECARA SPEKTROFOTOMETRI UV-VIS

Corticosteroids are drugs that contain synthetic steroid hormones. Dexamethasone sodium phosphate injection is a sterile preparation where a sterile preparation when opened will be exposed to air and microorganism in the surrounding environment, so that drug levels and potency will decrease. The use of steroid injection includes the use that is often used in hospitals and makes stock increase, this increase in preparations which often makes expired preparations will increase and become a problem in every hospital. This study aimed to determine the effect of storage at room temperature and refrigerator temperature on the level and physical quality of dexamethasone sodium phosphate injection before and after expiration. This study used dexamethasone sodium phosphate injection before and after expiration. The raw material for dexamethasone sodium phosphate is listed on the COA, 2022. The injection was stored at room temperature (<300C) and refrigerator temperature (2-80C) within 14 days, then organoleptic observation, pH test, and assay were carried out using UV-VIS Spectrophotometry. Quantitative analysis was carried out by comparing the levels of dexamethasone injection before and after the expiration date based on the linear regression chart and the paired sample t-test. The results obtained show that storage at room temperature and refrigerator temperature does not affect organoleptic observations, pH at the levels of dexamethasone sodium phosphate injection before and after expiration. Testing of dexamethasone sodium phosphate injection levels before and after expiration at room temperature storage (<300C) did not have a significant difference, while dexamethasone sodium phosphate injection levels before and after expiration at refrigerator temperature storage (2-80C) had a significant difference.

The fundamental efficacy of hesperidin-loaded/chitosan-coated hybrid nanoparticles as a prospective regimen in wound healing amendment: In vitro and in vivo comprehensive study

Hesperidin (Hsd), a promising bioactive phytomedicine, possesses a wound-healing activity. However, its poor solubility necessitates frequent topical application of high doses. Hence, this study aimed to prepare and characterize Hsd-loaded hybrid nanoparticles (Hsd-HNPs), followed by surface coating with chitosan (CS) to overcome such obstacles.Hsd was first encapsulated in a poly (D, L-lactic-co-glycolic) acid/soy phosphatidylcholine (PLGA/SPC) matrix, producing Hsd-HNPs, which were evaluated to choose the most appropriate one (F2). Then, F2 was coated with three concentrations of CS, and F2/CS1 was the optimal one, with a homogenous particle size of 254.10 ± 4.59 nm, a positive zeta potential of 24.23 ± 2.70 mV, a percent Hsd entrapping efficiency of 60.41 ± 4.56 %, and a percent yield of 75.67 ± 2.36 %. The stability of F2/CS1 was studied at a refrigerated temperature of 4 ± 1 °C. Then, it was incorporated into a gel base and subjected to further investigation of ex vivo skin permeation and in vivo wound healing activity.F2/CS1 demonstrated good stability at 4 ± 1 °C. The results of permeation studies manifested an enhanced pattern of Hsd permeation from F2/CS1 gel compared to that of the free Hsd. After topical application of F2/CS1 gel to the induced wound rat model, a significant and prominent wound healing efficacy was emphasized by histopathological and immunohistochemical examinations. In conclusion, Hsd/CS-HNPs (F2/CS1) gel could be regarded as promising topical nanophytomedicine with enhanced permeation and potentiated wound healing activity.

Development of a Simulator for Household Refrigerator Using Equation-Based Optimization Control with Bayesian Calibration

Conventional household refrigerators consist of a motor-driven compressor, evaporator, condenser, and expansion valve. To determine the optimal operation strategies of refrigerators, it is essential to investigate the overall system performance, using an appropriate simulator. This study proposed a data-driven simulator based on engineering features and machine learning algorithms for conventional household refrigerators. The most correlated variables for identifying the indoor temperature of refrigerators were identified using variable importance, and these were revealed to be the circulation fan speed, compressor operation status, and refrigerant flow direction. A data-driven simulator was constructed using Bayesian calibration, which considers the important variables, combined with a straightforward heat balance equation. The Markov Chain Monte Carlo approach was used to simultaneously calibrate three coefficients on the critical variables based on the heat balancing equation on each time step, which is consistent with the actual temperature of the container. The results revealed that the proposed approach (equation-based Bayesian calibration outperforms) standard machine learning algorithms, such as linear regression and random forest models, by 38.5%. Additionally, compared to the typical numerical analysis method, it can reduce the delivery time and effort required to develop a reliable simulator for household refrigerators.

Campylobacter Bacteriophage Infection at Refrigeration Temperatures

The application of bacteriophages to control foodborne bacterial pathogens in foods has gained traction in recent years. Poultry meat is a major source of Campylobacter jejuni, and a target for the application of bacteriophages. To offer the prospect of a post-harvest control measure, the bacteriophage must function at refrigeration temperatures, where C. jejuni does not grow but can survive. Here, we report actions of three classes of Campylobacter bacteriophage at 4 °C. The pre-incubation of broth cultures at 4 °C before a shift to 42 °C under conditions that support the growth of the host bacteria revealed differences in the time to lysis compared with cultures incubated at 42 °C. The pre-adsorption of the bacteriophage to a sub-population of bacteria is consistent with the observation of asynchronous infection. To ascertain whether the bacteriophages adsorb and infect (the commitment to replicate), we investigated bacteriophage transcription at 4 °C. RNA transcripts for all the bacteriophage host combinations were detected after 15 min, indicating that the interaction is not merely passive. Bacteriophages can infect C. jejuni at refrigeration temperatures, but the infection does not proceed to lysis in the absence of host cell division.

Temperature status of domestic refrigerators and its effect on the risk of listeriosis from ready-to-eat (RTE) cooked meat products

Inadequate domestic refrigeration is frequently cited as a factor that contributes to foodborne poisoning and infection, and consumer behaviour in this regard can vary largely. This study provides insight into the temperature profiles of domestic refrigerators in the Netherlands and the impact on the number of listeriosis cases related to ready-to-eat (RTE) cooked meat products. A survey was conducted among Dutch consumers (n = 1020) to assess their knowledge and behaviour related to refrigerators. Out of these participants, 534 measured their refrigerator's temperature, revealing an average temperature of 5.7 °C (standard deviation (SD) of 2.2 °C) with a maximum of 17 °C. Elderly people (65 years and older) had refrigerators with temperatures that were on average 0.6 °C higher than those of younger people (35 years or younger). The 24-hour temperature profiles of an additional set of actively surveyed refrigerators (n = 50) showed that the temperature measured on the upper shelf was significantly higher (mean 7.7 °C, SD 2.7 °C) than the temperature measured on the bottom shelf (5.7 °C, SD 2.1 °C). Quantitative Microbiological Risk Assessment (QMRA) predicted that the primary factors contributing to the risk of listeriosis were the initial concentration and the time and temperature during household storage. Scenario analysis revealed that storing opened RTE cooked meat products at home for either <7 days or at temperatures <7 °C resulted in a significant reduction of over 80 % in predicted illness cases. Among all illness cases, the elderly represented nearly 90 %. When assessing the impact of the disease in terms of Years of Life Lost (YLL), the contribution of the elderly was 59 %. Targeted communication, particularly directed towards the elderly, on the importance of storing RTE cooked meat products at the recommended temperature on the bottom or middle shelf as well as consuming within two to three days after opening, holds the potential to significantly reduce the number of cases.

Performance analysis of a dual-ejector enhanced two-stage auto-cascade refrigeration cycle for ultra-low temperature refrigeration

Auto-cascade refrigeration cycle (ARC) is a cost-effective solution for ultra-low temperature refrigeration. This paper proposes a dual-ejector enhanced two-stage auto-cascade refrigeration cycle (ETARC). In ETARC, two ejectors replace the throttle valves at the liquid phase outlet of the two gas–liquid separators in the conventional two-stage auto-cascade refrigeration cycle (CTARC). They are connected in series to recover partial expansion work in the throttling process, aiming to lift the suction pressure of the compressor. The ternary mixture component is selected and R600a/R41/R1150 is supposed to be the working fluid due to the best performance. The mass fraction ratio of the refrigerant mixture components, the quality at the inlet of two separators and the expansion ratio of the throttle valve (EPR) of the two cycles are optimized using particle swarm optimization (PSO) with respect to the maximum COP. The performances of the two cycles at optimum operating conditions are compared using energetic and exergetic methods, and the effect of the evaporation temperature and the condensation temperature on cycle performances and operating characteristics are discussed in detail. The results show that applying the two ejectors effectively improves the performance of ETARC. Compared with the CTARC at the evaporation temperature of −85℃, and the condensation temperature of 45℃, the ETARC cycle exhibits 16.07% improvement in COP, 29.43% increase in the volumetric refrigeration capacity qv, 17.17% reduction in the total exergy destruction rate. ETARC shows significant performance improvement and has a remarkable energy-saving potential.

Effect of incorporation of pumpkin seed powder and chia seed powder on storage stability of fiber enriched chicken meat nuggets

In the current investigation, the outcome of including powders of pumpkin seed (PSP) and chia seeds (CSP) on the various characteristics of nuggets prepared from chicken meat during storage at a refrigeration temperature of 4±1 °C was assessed. We sought to create functional chicken patties with increased nutritional properties, a longer shelf-life, and lower-oxidative rancidity. The effects of adding seed powders were evaluated using pH and TBARs measurements. The enhancement in the shelf-life of the nuggets prepared with CSP and PSP under refrigerated conditions was also confirmed by microbiological studies. Sensory tests were conducted to verify if these nuggets would be accepted by consumers. PSP at 3%, 6%, and 9% levels and CSP at 2%,4%, and 6% levels were individually added to the minced chicken meat. A significant (p < 0.05) rise in the pH values for all the treatments with the advancement in the storage period was observed. The thiobarbituric acid (TBA) value also increased in all treatments during refrigerated storage, but the treated nuggets had significantly (p < 0.05) lower TBA values towards the end of the storage period. We concluded that the control as well as the treated nuggets were moderately acceptable and microbiologically safe up to the 12th day of storage under refrigeration.

Seasonal stress on semen quality profiles, seminal biochemical and oxidative stress attributes in endangered Teressa goat of Andaman and Nicobar Islands

Objective: To measure seasonal effects on semen quality profiles, seminal biochemical and oxidative stress attributes in fresh and liquid stored semen in monsoon and dry seasons. Methods: A total of 10 Teressa bucks (3-4 years) were selected from breeding farm, ICAR-Central Island Agricultural Research Institute, Port Blair, Andaman and Nicobar Islands, India. Semen samples (n=25 per season) were collected through artificial vagina method and preserved at refrigerated temperature (5°C) for 48 h using Tris citrate glucose based extender. We detected semen quality parameters [volume, mass activity, pH, sperm concentration, total motility, viability, total sperm abnormality, and plasma membrane, acrosomal and nuclear integrities], biochemical profiles [aspartate amino transferase (AST), alanine amino transferase (ALT) and total cholesterol], and oxidative stress markers [total antioxidant capacity (TAC) and malondialdehyde (MDA)] during monsoon and dry seasons. Results: Semen quality parameters significantly differed between seasons (P&lt;0.05) and among storage periods (P&lt;0.05). Volume, pH, mass activity, motility, viability, acrosomal, plasma membrane and nuclear integrities, and TAC were significantly higher (P&lt;0.05). Sperm concentration, sperm abnormalities, MDA, AST, ALT and total cholesterol were significantly lower in fresh semen of monsoon than dry season (P&lt;0.05). Motility, viability, acrosomal, plasma membrane and nuclear integrities, and TAC were significantly decreased (P&lt;0.05) while sperm abnormality, AST, ALT, total cholesterol and MDA were significantly increased as liquid semen storage period advanced (P&lt;0.05). Conclusions: Monsoon season has higher beneficial effects on semen quality profiles and liquid stored semen remained usable for upto 48 h. Good quality ejaculates with higher TAC and lower MDA can be cryopreserved and will be used for artificial insemination.

Retrogradation-induced physicochemical changes in pre-cooked rice noodles stored at different temperatures: a viewpoint from water dynamics and structure.

There has been significant interest in pre-cooked noodles that have a long shelf life and are convenient to cook. However, the thermal processes during preparation, and their high moisture content, can lead to significant quality deterioration during storage. Nevertheless, a comprehensive evaluation of these quality losses has not yet been conducted. The effects of different storage temperatures (25, 4, and -20 °C) on the retrogradation-related physicochemical changes in pre-cooked rice noodles were elucidated mainly from the water dynamics and structural viewpoints. Thermal analysis demonstrated that amylopectin recrystallization took place in the noodles stored at refrigerated temperature, followed by room temperature. The refrigerated storage accelerated the starch retrogradation that caused the water molecules to become entrapped within the crystalline structure by lowering the water hydration properties and weighted T2 relaxation times of the pre-cooked noodles. These water mobility patterns were correlated with the textural changes in the noodles (greater hardness and Rmax /extensibility). Furthermore, the higher structural density and thickness derived from starch retrogradation were observed in the tomographic and microscopic images of the refrigerated noodles. The principal component analysis demonstrated that various physicochemical changes of the pre-cooked noodles during storage showed high correlations with the degree of starch retrogradation (r > 0.83). The physicochemical features of the precooked noodles stored under refrigerated conditions were involved in the molecular dynamics of water, showing a notable water mobility reduction derived from the starch retrogradation, which contributed to their thermal, tomographical, and textural changes. © 2023 Society of Chemical Industry.

The Effects of Alcoholic Extract of Ficus carica Leaves on Some Chemical and Microbiological Properties of Beef during Refrigerated Storage

This study explored the preservative effects of the alcoholic leaves’ extract of Ficus carica plant on beef refrigerated for 15 days. Phytochemical analysis showed that the plant extract contained terpenoids, flavonoids, tannins, saponins, and alkaloids. Furthermore, the alcoholic extract of plants significantly reduced the total viable counts of psychrotrophic bacteria, pathogenic bacteria (Proteus, Salmonella typhimiurum, Escherichia coli, and Staphylococcus aureus), and yeasts (Candida kruse, Candida lambica, and Zygosaccharomyces) isolated from meat samples, particularly at 100 and 200 mg/ml concentrations. The antioxidant activity of the extract was determined by using TBA and TVN values. The results showed that meat samples treated with 100 and 200 mg/ml of the alcoholic extract of F. carica had significantly lower TBA values (25, 0.24 mg/kg respectively) on day 5 which became 0.92, 0.53 mg/kg on day 15. Whereas the control values increased from 0.25 to 1.75 mg/kg on day 15,f ollowed by the TVN values of treatment meat samples with 100 and 200 mg/ml 5.57, 5.12 mg N/100 g meat respectively on day 5 which became 12.16, 10.65 mg N/ 100 g meat on day 15, while the TVN in control samples increased significantly (p &lt; 0.05) from 7.35 to 15.76 mg N/100 g meat. All results confirmed that the alcoholic extract of F. carica, which is rich in bioactive compounds is more effective as a natural antibacterial, antifungal and antioxidant, than synthetic antioxidants that maintain the quality of beef, compared to the control by reducing lipid oxidation and microbial growth at refrigeration temperatures, especially at 100 and 200 mg/ml concentrations of the plant extract.

Efek Temperatur dan Waktu Terhadap Total Kandungan Antioksida Dari 5 Jenis Tanaman Herbal dengan Metode Phenanthroline Termodifikasi

This research determines the effect of temperature, maceration time, extract storage time at room temperature and refrigerator temperature of the total antioxidant content in miana leaves (Plectranthus scutellarioides (L.)R. Br), papaya leaves (Carica papaya), rambutan leaves (Nephelium lappaceum), bay leaves (Eugenia polyantha) and green betel leaves (Piper betel L). The determination of total antioxidant content was carried out by modified phenanthroline method. Based on the research data. It was found that the optimum conditions for total antioxidant content in the samples above were at 100oC with 60 minutes of maceration time and without storage time of the extracted samples before being analyzed. The total antioxidant content of miana leaves, papaya leaves, rambutan leaves, bay leaves, and green betel leaves analyzed in the optimum conditions are 3.0865; 1.1554; 0.4641; 0.6764; and 3.3630 mmol Fe/g DW, respectively.

Microbial contamination and some chemical and physical properties of date fruits stored at room and refrigerator temperatures

Purpose The purpose of this article is to investigate on changes of the microbial load and the chemical and physical properties of date fruits stored for 6 months under two different temperatures.Design/methodology/approachA composite sample of 100 kg date fruits from the Khalas variety, season 2019, was collected from the local market in Al Ahsa Province, Saudi Arabia, packaged in 1 kg lots, stored at room and refrigerator temperatures and the microbial contamination and the chemical and physical properties monitored over a period of six months of storage. Total bacteria, lactic acid bacteria, Enterobacteriaceae, yeasts and molds were counted and representatives of yeast and mold contaminants were identified using morphological, physiological and molecular typing techniques. Changes in the color and texture of the samples were also monitored during storage.Findings The yeasts detected were two strains of each of Lachancea thermotolerans and Rhodosporidiobolus fluvialis and one strain of Cystofilobasidium lacus-mascardii. For molds, one strain of each of Aspergillus niger, Aspergillus flavus, Penicillium chrysogenum and Aspergillus caespitosus have been detected. No significant growth of these microorganisms was observed, but enough load persisted during storage that makes the samples not meeting the microbiological standards. There were significant changes in the color and texture of the fruits during storage.Originality/value These findings add important information that can help producers and processors to improve quality and promote marketing of date fruits, especially to international markets.

Analysis and optimization of injection characteristics and comprehensive performance of low GWP refrigerant HP-1 in high temperature heat pump systems

In the context of low-GWP refrigerants becoming a research hotspot, the environmentally friendly refrigerant HP-1 with independent intellectual property rights in China has demonstrated significant advantages in fields such as data centers and 5G base stations. However, there are few applied studies in the field of high-temperature heat pumps (HTHPs), therefore, in this study, HP-1 was utilized in HTHP system and this process was combined with the injection technology. It has been proven to be an effective approach for performance improvement. The injection characteristics of HP-1-based HTHP were analyzed and optimized with a focus on safety, stability, and efficient operation. The application advantages of HP-1 were compared and analyzed in terms of thermodynamic performance and Total Equivalent Warming Impact. The results indicated that there were three types of characteristic injection pressures based on system performance, corresponding to the maximum coefficient of performance (COP), the lowest electronic expansion valve inlet refrigerant temperature, and the lowest exhaust temperature of the compressor. Further, the corresponding control equations for injection pressure were obtained. Based on the safety injection pressure, the optimal COP under injection pressure could effectively improve the COP of the system by 2.1–5.2 %, and the exhaust temperature also increased by 6.1–10.1 %. When the temperature of the heat source was 50 °C and the target heating temperature was 120 °C, the heating capacity of HP-1 increased by 10.8 % compared with that of R245fa, the COP of the system increased by 2.7 %, and the volume heating capacity increased by 10.3 %. Moreover, the emission reduction effect of HP-1 was significant, and the carbon dioxide emissions were reduced by 15.4–39.1 %. The analysis shows that HP-1 exhibits better performance and environmental characteristics than HFC-245fa. This study is of guiding significance to improve the thermodynamic performance of HTHP, for the safe and efficient operation and energy saving and emission reduction in the industrial field.

Impact of heat-set and cold-set gelling polysaccharides on potato protein gelation: Gellan gum, agar, and methylcellulose

The plant-based meat market is growing due to concerns about the sustainability of the modern food system. Plant-based meats are often constructed from blends of food biopolymers, such as plant proteins and polysaccharides. This study characterizes the thermal setting properties of potato protein (10%) and polysaccharide (2 wt%) mixtures containing polysaccharides with different reversible gelling behaviors: agar (cold set); gellan gum (cold set); or methyl cellulose (heat set). Each sample was heated above the thermal denaturation temperature of the potato proteins to promote protein unfolding, aggregation, and network formation. The addition of the polysaccharides tended to increase the complex shear modulus of the biopolymer blends before heating but increase or decrease it after heating depending on polysaccharide type. The shear modulus and hardness of the gels formed after heating tended to increase after addition of the cold-set polysaccharides but decrease after the addition of the heat-set polysaccharides, especially at refrigerator temperatures. Differential scanning calorimetry data showed that the potato proteins underwent irreversible denaturation after heating for all samples. Zeta-potential analysis showed that the potato proteins and all polysaccharides were negatively charged under the pH conditions used. There was greater water loss during heating for the composite gels containing methyl cellulose, which may have been due to its increase hydrophobicity at high temperatures. Appearance and microstructure analysis showed that phase-separation occurred after mixing the polysaccharides with the potato proteins, which was attributed to a segregation mechanism. The knowledge obtained from this study may help the food industry to optimize protein-polysaccharide blends to create gels with characteristics and structures that can mimic different plant-based meat products.

An approach to improve the efficiency of cooling enhancement of a thermoelectric refrigerator through the use of phase‐change materials

AbstractIn this study, a technique is suggested to enhance the temperature difference for cooling and energy efficiency of thermoelectric cooler (TEC) used in cooled detectors when subjected to high current conditions. Embedding a structure for storing heat during phase change is the basis of this method at the heat sink. A simulation model was created for a common two‐stage series TEC with an asymmetrical design, which is coupled with a structure for storing heat through phase change. The research examined how phase transition heat storage impacts the coefficient of performance (COP) and refrigeration temperature difference across various phase‐change substances, heat transfer coefficients at the hot end, currents, and the height of the phase‐change material (PCM). The findings suggest that the suggested approach of combining PCM with TEC can efficiently lower the cold end temperature of TEC by a maximum of 20 K, enhance the temperature gap by a maximum of 16 K, and preserve the consistency of the optimized quantity across various hot end heat transfer coefficients. During the phase‐change process of PCMs, the COP of TECs integrated with PCM is found to increase by an average of 2%–3% compared to TECs without PCM integration. Under the maximum current operating condition, the cryogenic temperature can be optimized to a minimum of 238 K. In summary, the proposed method of integrating phase‐change heat storage with TECs provides a promising solution for improving their cooling performance and energy efficiency in cooled detectors under high current conditions. Additional investigation can be conducted to explore the practical application of this approach and enhance the design parameters for various uses.

Vapor-liquid equilibrium data and performance analysis on binary mixture of R32 and R1216 for residential air condition system

In order to accurately evaluate the performance of R32 and unsaturated fluorinated olefins (HFOs) binary mixtures in residential air condition (RAC) system, the vapor-liquid phase equilibrium (VLE) data of R32 and R1216 binary mixture has been measured with a liquid phase circulation system in the temperature range from 285 to 315 K. The experimental data were correlated by Peng-Robinson (PR) equation of state with Huron-Vidal (HV) mixing rule and non-random two-liquid (NRTL) activity coefficient model. Maximum deviation of the pressure and the mole fraction was 1.38% and 0.013, respectively. The azeotropic behavior was observed for the R32 and R1216 binary mixture when the mole fraction of R32 was around 0.9. The RAC system with standard refrigeration, heating and variable evaporation temperature operating condition was simulated. The cycle performance of binary mixtures of R32 + R1216, R1234yf and R1234ze(E) at different concentrations was compared. The azeotrope R32/R1216 (molar ratio 0.9/0.1) has an extremely low GWP, the COP, refrigeration/heating capacity per unit volume and condensation pressure close to pure R32, and lower discharge temperature. At the same time, it also has well variable operating conditions performance and can be considered as a drop-in replacement for R32 and R410A in RAC systems.