Search Results (3,047)

This study aims to investigate the differences in the effects of spraying and immersing methods on edible coatings for halved and pitted plums. Earlier studies have shown that these biodegradable packaging materials can preserve the quality and safety of fruits for an extended shelf life. Halved and pitted plums (variety Stanley) were treated with chitosan and rosehip oil edible coating emulsions by spraying and immersing methods. The treated series were analyzed by physical, physicochemical, microbiological, and sensorial methods during refrigerated storage for nine days, until the onset of microbiological spoilage. At the beginning of the storage, there was a visible difference between the differently treated samples. The untreated series showed the fastest browning. The emulsion-sprayed samples presented the least changes in color, shape, and volume. A weaker effect of the immersion technique can be explained by a deep standing of the fruits in a treating solution or emulsion. Some of the immersed samples have an aqueous texture and received a smaller sensory rating. The advantages and disadvantages of the methods need further investigation, but on a production scale, spraying can guarantee uniform batches. In laboratory circumstances, immersion is an easier method that does not need expensive and difficult-to-use equipment and gives good results. Full article

Ready-to-eat meat products face quality challenges during storage and reheating. This study aimed to (i) characterize the physicochemical/microbiological changes in stewed mutton during storage (4 °C/−18 °C, 0–28 days) and (ii) evaluate reheating methods (boiling vs. microwaving) on day-7 samples. The nutritional analysis confirmed moisture reduction (57.32 vs. 72.12 g/100 g)-concentrated protein/fat levels. Storage at −18 °C suppressed microbial growth (the total plate count (TPC), 3.73 vs. 4.80 log CFU/g at 28 days; p < 0.05) and lipid oxidation (thiobarbituric acid reactive substances (TBARS): 0.14 vs. 0.19 mg/kg) more effectively than storage at 4 °C. The total volatile basic nitrogen (TVB-N) kinetics projected a shelf life ≥90 days (4 °C) and ≥120 days (−18 °C). Microwave reheating after frozen storage (−18 °C) maximized the yield (86.21% vs. 75.90% boiling; p < 0.05) and preserved volatile profiles closest to those in the fresh samples (gas chromatography–mass spectrometry (GC-MS)/electronic nose). The combination of freezing storage and subsequent microwave reheating has been demonstrated to be an effective method for preserving the quality of a precooked lamb dish, thereby ensuring its nutritional value. Full article

Ternary choline chloride-based deep eutectic solvents (TDESs) exhibit unique physicochemical properties, including lower viscosities, lower melting points, higher thermal stabilities, and enhanced solvations compared to binary deep eutectic solvents (BDESs). Although BDESs have been widely studied, the addition of a third component in TDESs offers opportunities to further optimize their performance. This review aims to evaluate the physicochemical properties of TDESs and highlight their potential applications in sustainable industrial processes compared to BDESs. A comprehensive analysis of the existing literature was conducted, focusing on TDES properties, such as phase behavior, density, viscosity, pH, conductivity, and the effect of water, along with their applications in various fields. TDESs demonstrated superior physicochemical characteristics compared to BDESs, including improved solvation and thermal stability. Their applications in biomass conversion, CO₂ capture, heavy oil upgrading, refrigeration gases, and as solvents/catalysts in organic reactions show significant promise for enhancing process efficiency and sustainability. Despite their advantages, TDESs face challenges including limited predictive models, potential instability under certain conditions, and scalability hurdles. Overall, TDESs offer significant potential for advancing sustainable and efficient chemical processes for industrial applications. Full article

Subcooling-based ice slurry production faces challenges in terms of energy efficiency and operational stability, which limit its applications for large-scale cold energy storage. A thermodynamic model is established to investigate the effects of key control parameters, including evaporation temperature, condensation temperature, subcooling degree, water flow rate, type of refrigerant, and adiabatic compression efficiency. The results show that using the refrigerant R161 achieves the highest energy efficiency, indicating that R161 is the optimal refrigerant in this research. When the evaporation and condensation temperatures are −10 °C and 30 °C, respectively, the system achieves the maximum comprehensive performance coefficient of 2.43. Moreover, under a flow velocity of 0.8 m/s and a temperature of 0.5 °C, the system achieves a peak ice production rate of 45.28 kg/h. A high water temperature and high flow velocity would significantly degrade the system’s ice production capacity. This research provides useful guidance for the design, optimization, and application of ice slurry-based cold energy storage systems. Full article

With the increasing awareness of energy consumption issues, there has been a growing emphasis on energy-saving retrofits for central air-conditioning systems that constitute a significant proportion of energy consumption in buildings. Efficient energy utilization can be achieved by optimizing the modeling of the equipment within the chiller plants of central air-conditioning systems. Traditional modeling approaches have been static and have focused on modeling within narrow time frames when a certain amount of equipment operating data has accumulated, thus prioritizing the precision of the model itself while overlooking the fact that energy-saving retrofits are a long-term process. This study proposes a modeling scheme for the equipment within chiller plants throughout the energy-saving retrofit process. Based on the differences in the amount of available operating data for the equipment and the progress of retrofit implementation, the retrofit process was divided into three stages, each employing different modeling techniques and ensuring smooth transitions between the stages. The equipment within the chiller plants is categorized into two types based on the clarity of their operating characteristics, and two modeling schemes are proposed accordingly. Based on the proposed modeling scheme, chillers and chilled-water pumps were selected to represent the two types of equipment. Real operating data from actual retrofit projects was used to model the equipment and evaluate the accuracy of the model predictions. The results indicate that the models established by the proposed modeling scheme exhibit good accuracy at each stage of the retrofit, with the coefficients of variation (CV) remaining below 6.88%. Furthermore, the prediction accuracy improved as the retrofitting process progressed. The modeling scheme performs better on equipment with simpler and clearer operating characteristics, with a CV as low as 0.67% during normal operation stages. This underscores the potential application of the proposed modeling scheme throughout the energy-saving retrofit process and provides a model foundation for the subsequent optimization of the refrigeration system. Full article

In this study, we investigated the effects of air packaging, vacuum packaging and modified atmosphere packaging (CO₂/N₂: 80/20) on the purine metabolism and enzyme activities of refrigerated large yellow croakers. The results showed that modified atmosphere packaging significantly inhibited microbial growth, delayed adenosine triphosphate degradation and maintained higher IMP content (1.93 μmol/g on day 21) compared to the air packaging group (2.82 μmol/g on day 12). The total purine content increased with storage time, with hypoxanthine content increasing significantly and occupying most of the total content, which was the key factor for the elevation of purine, followed by adenine content showing a significant decreasing trend. Hypoxanthine accumulation was significantly suppressed in the modified atmosphere packaging group (2.31 μmol/g on day 18), which was much lower than that in the air packaging group (5.64 μmol/g), whereas xanthine and guanine did not show significant differences among the groups. The key enzymes xanthine oxidase and purine nucleoside phosphorylase were much less active in modified atmosphere packaging, effectively delaying the cascade reaction of inosine monophosphate → hypoxanthine → xanthine. The study confirmed that modified atmosphere packaging intervenes in purine metabolism through enzyme activity regulation, providing a theoretical basis for the preservation of low purine aquatic products. Full article

Photovoltaic–thermal (PVT) technology has attracted considerable attention for its ability to significantly improve solar energy conversion efficiency by simultaneously providing electricity and heat during the day. PVT technology serves a purpose in condensers and subcoolers for passive cooling in refrigeration systems at night. In our previous work, we proposed a switchable film-insulated photovoltaic–thermal–passive cooling (PVT-PC) module to address the structural incompatibility between diurnal and nocturnal modes. However, the performance of the proposed module strongly depends on two key design parameters: the structural height and the vacuum level of the air cushion. In this study, a numerical model of the proposed module is developed to examine the impact of design and meteorological parameters on its all-day performance. The results show that diurnal performance remains stable across different structural heights, while nocturnal passive cooling power shows strong dependence on vacuum level and structural height, achieving up to 103.73 W/m² at 10 mm height and 1500 Pa vacuum, which is comparable to unglazed PVT modules. Convective heat transfer enhancement, induced by changes in air cushion shape, is identified as the primary contributor to improved nocturnal cooling performance. Wind speed has minimal impact on electrical output but significantly enhances thermal efficiency and nocturnal convective cooling power, with a passive cooling power increase of up to 31.61%. In contrast, higher sky temperatures degrade nocturnal cooling performance due to diminished radiative exchange, despite improving diurnal thermal efficiency. These findings provide fundamental insights for optimizing the structural design and operational strategies of PVT-PC systems under varying environmental conditions. Full article

The aim of this study was to prevent the development of microorganisms in the refrigerated storage of tench by releasing allyl isothiocyanate (AITC) produced by black mustard seeds. Tench reared in an aquaculture centre were sacrificed and the fillets were separated. Different amounts of defatted mustard seed (300, 400 and 500 mg) were added to hermetic polypropylene trays. Microbiological, sensory, and gas chromatography with MS detection analysis were done. AITC release increased progressively until the third day of storage, significantly delaying the development of microorganisms in samples with higher mustard seed content. The tasting panel detected positive aromas at the beginning of the study, but these decreased and negative aromas appeared. The mustard seed treatment resulted in a higher positive aroma at the end of the storage, reducing rotting and ammonia odours. A total of 31 volatile compounds were detected and grouped into hydrocarbon, alcohol, benzenoid, isothiocyanate, ketone, acetate, aldehyde, and others. Butylated hydroxytoluene, an indicator of bacterial contamination, was the major aromatic compound found during storage. The release of AITC resulted in fewer organic compounds with negative aromas appearing during storage. PCA analysis allowed us to classify the assays during storage according to their volatile profiles, confirming the differences observed between treatments. Thus, adding mustard seed to fish packaging could be a viable alternative to extending the product’s shelf life and ensuring food safety. Full article

This study investigates Bimi^® (Brassica oleracea Italica × Alboglabra), a hybrid between kailan and conventional broccoli, to evaluate its compositional, functional, and sensory properties in relation to industrial sous-vide processing and refrigerated storage. Proximate composition, amino acid and fatty acid profiles, and mineral content were determined in raw samples. Color, chlorophyll content, total polyphenols, and antioxidant capacity (FRAP, ABTS, DPPH) were analyzed before and after sous-vide treatment and following 60 days of storage. Microbiological and physicochemical stability was monitored over 90 days under standard (4 °C) and mildly abusive (6–10 °C) storage conditions. Sensory profiling of Bimi^® and conventional broccoli was performed on sous-vide samples. The results showed an increase in total polyphenols and antioxidant activity after processing, while chlorophylls decreased. Microbiological safety was maintained under all conditions, with stable water activity and only moderate acidification. Bimi^® provided a valuable source of protein (4.32 g/100 g FW, 8.63% RDA), appreciable amounts of dietary fiber (2.96 g/100 g FW, 11.85% RDA), and essential minerals such as potassium (15.59% RDA), phosphorus (14.05% RDA), and calcium (8.09% RDA). Sensory evaluation revealed a milder flavor profile than that of conventional broccoli, accompanied by an asparagus-like aroma. These findings support the suitability of Bimi^® for industrial sous-vide processing and its potential as a nutritious convenience food. Full article

Taconis oscillations represent spontaneous excitation of acoustic modes in tubes with large temperature gradients in cryogenic systems. In this study, Taconis oscillations in hydrogen and helium systems are enhanced with a porous material resulting in a standing-wave thermoacoustic engine. A theoretical model is developed using the thermoacoustic software DeltaEC, version v6.4b2.7, to predict system performance, and an experimental apparatus is constructed for engine characterization. The low-amplitude thermoacoustic model predicts the pressure amplitude, frequency, and temperature gradient required for excitation of the standing-wave system. Experimental measurements, including the onset temperature ratio, acoustic pressure amplitudes, and frequencies, are recorded for different stack materials and geometries. The findings indicate that, independent of stack, hydrogen systems excite at smaller temperature differentials than helium (because of different properties such as lower viscosity for hydrogen), and the stack geometry and material affect the onset temperature ratio. However, pressure amplitude in the excited states varies minimally. Initial measurements are also conducted in a cooling setup with an added regenerator. The configuration with stainless-steel mesh screens produces a small cryogenic refrigeration effect with a decrease in temperature of about 1 K. The reported characterization of a Taconis-based thermoacoustic engine can be useful for the development of novel thermal management systems for cryogenic storage vessels, including refrigeration and pressurization. Full article

This study investigated the effect of an apple pectin coating enriched with gamma-decalactone (GDL) on the physicochemical and microbiological quality of strawberries over 9 days of refrigerated storage. Strawberries were coated with pectin solutions containing a plasticizer and emulsifier, with or without GDL, and compared to uncoated controls. The coatings were evaluated for their effects on fruit mass loss, pH, extract content (°Brix), firmness, color parameters (L*, a*, b*, C*, h*, ΔE), and microbial spoilage. The pectin coating limited changes in extract, pH, and color and slowed firmness loss. Notably, GDL-enriched coatings significantly reduced spoilage (14.29% after 9 days vs. 57.14% in the control) despite accelerating pulp softening. Extract content increased the most in the GDL group (from 9.92 to 12.00 °Brix), while mass loss reached up to 22.8%. Principal Component Analysis (PCA) confirmed coating type as a major factor differentiating sample quality over time. These findings demonstrate the potential of bioactive pectin-based coatings to enhance fruit preservation and support the development of active packaging strategies. Further studies should optimize coating composition and control the release kinetics of functional compounds. Full article

To study the effect of cold plasma (CP) on the refrigerator shelf life of coconut water, microorganism growth and diversity and physicochemical properties were investigated. Results indicated that CP treatment did not cause significant color changes in coconut water, with turbidity remaining lower than the control even after 6 days of storage. Enzymatic activity analysis revealed reduced polyphenol oxidase (PPO) and peroxidase (POD) levels in treated samples. Specifically, the 12 s CP treatment resulted in the lowest antioxidant capacity values: 15.77 Fe²⁺/g for ferric reducing antioxidant power (FRAP), 37.15% for DPPH radical scavenging, and 39.51% for ABTS⁺ radical scavenging. Microbial enumeration showed that extended CP treatment effectively inhibited the growth of total viable counts, psychrophilic bacteria, lactic acid bacteria, and yeast. High-throughput sequencing identified Leuconostoc, Carnobacterium, and Lactobacillus as the dominant bacterial genera. During storage, Carnobacterium was the primary genus in the early stage, while Leuconostoc emerged as the dominant genus by the end of the storage period. In summary, CP as an effective non-thermal technology was able to maintain quality and antioxidant capacity, inhibit microbial growth, and delay the spoilage in coconut water to help extend the refrigerated shelf life of the product. Full article

Combining Organic Rankine Cycles (ORC) with cooling cycles offers a promising approach to achieving greater outputs within a single system. In this study, a novel directly combined ORC-VCC system has been designed to not only meet the cooling demand using a geothermal heat source but also generate power. The proposed novel ORC-VCC system has been analyzed for its energetic performance using four selected fluids: R290, R600a, R601, and R1234ze(E). Parametric analysis has been conducted to investigate the effects of parameters of heat source temperature, heat source mass flow rate, cooling capacities, condenser temperature, ORC evaporator temperature, pinch point temperature difference and isentropic efficiencies on net power production. Among the working fluids, R290 has provided the highest net power production under all conditions in which it was available to operate. Additionally, the results have been analyzed concerning a reference cycle for comparative evaluation. The proposed novel cycle has outperformed the reference cycle in all investigated cases in terms of net power production such as demonstrating an improvement of approximately from 8.7% to 57.8% in geothermal heat source temperature investigations. Similar improvements have been observed over the reference cycle at lower heat source mass flow rates, where net power increases by up to 50.8%. Full article

Contaminated seeds pose a major risk in hydroponic systems, as a single contaminated seed can compromise the entire setup. Effective decontamination strategies are essential to control seed-borne pathogens. Pecan shells, a byproduct comprising nearly 50% of the nut’s weight, have demonstrated antimicrobial properties against key pathogens. This study evaluated pecan shell extract (PSE) as a treatment to inactivate Listeria monocytogenes, Escherichia coli O157:H7, and Pseudomonas spp. on lettuce seeds and its effect on germination. Lettuce seeds were inoculated with L. monocytogenes strains (101 M, V7, LCDC, and Scott A) and treated with PSE (1:10 w/v) either by coating in sodium alginate or priming for 6 h (4 °C or room temperature). Hydropriming was used as a control. Additional trials with E. coli and Pseudomonas spp. tested PSE at 1:10, 1:20, and 1:30 w/v ratios. Priming at refrigeration significantly reduced Listeria levels. E. coli priming treatments showed significant reductions at 1:20 and 1:30 w/v. For Pseudomonas, priming at 1:20 showed the highest reduction. PSE priming also enhanced germination (88.3%), outperforming other treatments. These findings suggest PSE is a sustainable and effective seed treatment to reduce microbial contamination and enhance seed germination in hydroponic systems. Full article

Per- or polyfluoroalkyl substances (PFASs) are man-made compounds involved in compositions of many industrial processes and consumer products. The largest-volume man-made PFAS are made up of refrigerants and fluoropolymers. Major concerns for our society related to these substances are their contribution to global warming as greenhouse gasses and the potential for adverse effects on living organisms, particularly by long-chain perfluoroalkyl acid derivatives. Restrictions on manufacturing and applications will increase in the near future. The full remediation of historical and current contaminations of air, soil and water remains problematic, especially for ultra-short PFASs, such as trifluoroacetic acid. Future monitoring of PFAS levels and their impact on ecosystems remains important. PFASs have become integrated in the lifestyle and infrastructures of our modern worldwide society and are likely to be part of that society for years to come in essential applications by closing the fluorine loop. Full article