Thermal Process Research Articles

Comparison of volatiles evolving from selected highland and mare lunar regolith simulants during vacuum sintering

Volatiles evolving from JSC-1A, NU-LHT-4M and CSM-LHT-1G lunar regolith simulants during in vacuo thermal processing were analyzed using mass spectrometry as a function of temperature. Two high-fidelity simulants, JSC-1A (mare) and NU-LHT-4M (highland), were compared to a newly developed CSM-LHT-1G highland simulant, modified to closely match lunar geochemistry. Large autogenous gas loads were observed for all investigated materials. Mineralogical knowledge was used to identify and attribute individual volatile species to reacting, transforming, or decomposing constituents (hydrates, carbonates, sulfates, sulfides, clays, etc.) of the respective regolith simulant in the self-generated gas environment. Cumulative mass losses for individual simulant components as a function of temperature were quantified using mass spectrometry in conjunction with thermogravimetric analysis. Investigation of the four components of CSM-LHT-1G – anorthosite, basalt, augite, and glass – aided the attribution of volatile species to specific compounds and their respective sources. The results showed significant decomposition of non-lunar phases present in the man-made regolith simulants below the typical glass crystallization temperatures, which paves the way to devising methods for enhancing the fidelity of the simulants. High gas loads and corrosive gases (HF and HCl) were recognized as potential hazards, pertaining to the development of large testbed facilities.

Numerical simulation and experimental analysis of thermal conduction and stress in laser cladding repair of thin-walled parts

To minimize the deformation of thin-walled parts during the laser cladding process and enhance the quality of the repaired parts, the Finite Element Abaqus software was used to develop a thermal conduction and 3D stress model, the heat source used in the experiments was a double ellipsoid heat source model. This model simulates the thermal process and the deformation resulting from residual stresses in the laser cladding process on a titanium alloy substrate with a thickness of 2 mm. Through the simulation, the temperature field of the substrate at the end of each pass was obtained, and the cladding sequence with the smallest temperature gradient during the multi-pass laser melting process was determined. By combining simulation and practice, the multilayer stacking pattern was optimized to achieve deformation control. Analog simulation experiments indicate that the optimized single-layer multi-pass laser cladding method results in less heat accumulation and thermal stress compared to the unidirectional sequential scanning method. The flatness test results show that the specimens have less deformation with the optimized multilayer stacking method. In addition, the metallographic organisation of the two cladding specimens is analysed in this paper, and the results show that the optimised specimens exhibit excellent microstructures and properties.

Identification of digestion-resistant peptides in various processed peanut reveals their distinct allergenicity

Peanut protein is a significant food allergen that can trigger severe reactions. The allergenicity of peanut protein may be affected by the thermal processing method and matrices, and its anti-digestibility may also change accordingly. This study investigated how three heat treatment techniques affect the allergenicity and digestibility of peanut proteins and compared the differences in anti-digestive peptide segments by Mass spectrometry. Results showed that boiling and frying reduced sensitization, while roasting potentially increased it. After gastric digestion, allergenicity of Ara h 1 decreases due to breakdown of allergenic peptide segments. Hydrophobic regions of Ara h 1 where monomers interact resist degradation. Compared to boiling and frying, roasting can retain more allergenic peptides containing PGQFEDFF, YLQGFSRN, QEERGQRR, HRIFLAGDKD, and KDLAFPGSGE allergenic epitopes even after prolonged digestion. Meanwhile, digestion-resistant epitopes were affected by matrix and thermal treatments. These findings underscore the potential implications for food processing and allergy management strategies.

Effect of hot-wire method on microstructure and mechanical properties of wire arc additive repaired superalloy

This study shows that the hot wire is an effective way to reduce the amount of undesirable Laves phase during the repair of 718Plus components, which are detrimental to the mechanical properties. The complex relationship between microstructure and hotwire was studied in detail. Five damaged components were repaired by depositing the melted 718Plus wire onto the wrought substrate using directed energy deposition-arc (DED-arc). A finite element model was used to provide clues for the thermal process analysis. The hot-wire method enhanced the cooling rate of the molten pool and suppressed the remelting behaviour of secondary dendritic arms (SDA) in the reheated zone. The resultant microstructure contained refined dendrites with more obvious SDA, which allows the production of tiny reticular Nb-rich liquid spots between dendrites during final solidification stage. These spots beyond a threshold of Nb could cause eutectic reaction, leading to the morphologic transformation from long-stripped to granular Laves phase and a lower volume fraction. Moreover, the hot-wire method hindered the dynamic precipitation of γ' phase due to the shortened precipitation time, which was responsible for the inferior mechanical properties. The heat-treatment re-optimized the precipitation of γ' phase and further dissolved Laves phase to release more Nb for γ' phase, which leads to the improvement of strength about 10 %.

Characterization of the in-situ degradation process of P3HT:PCBM based on hyperspectral and neural networks

In situ online observation of surface morphology during degradation processes is of paramount importance for exploring the stability of organic photovoltaic materials. In this study, we designed an in situ online characterization system based on hyperspectral and neural network technologies, and observed the degradation processes of P3HT:PCBM thin film materials. The system is capable of collecting hyperspectral image data from 101 channels within the 400–700 nm wavelength range for characterizing detailed surface features of materials. Additionally, to automate the processing of hyperspectral image data, we designed a spectral image segmentation algorithm based on neural networks and proposed a foreground attention mechanism to improve the segmentation accuracy of the algorithm. The experimental results indicate that the system can achieve high spectral characterization of P3HT:PCBM thin film materials and automate image data processing through artificial intelligence algorithms, with an image segmentation accuracy of 99.62 %. Furthermore, owing to the higher spectral resolution of this system and its computer-assisted analysis capabilities for material image data, not only are the in-situ variations in size, density, and formation rate of aggregates formed during the thermal degradation process of P3HT:PCBM thin film materials experimentally analyzed, but also the fluorescence changes at the edges of aggregates during the photodegradation process are revealed. The reliable code can be found at the following link: https://github.com/HyperSystemAndImageProc/IONFMDP-UHHNN.

Temperature-Dependent Oxidation Behavior of Silicon Carbide Surface: Reactive Molecular Dynamics Simulations.

The high-temperature oxidation mechanism of silicon carbide (SiC) is crucial for designing thermal protection systems in aircraft. This study explored the oxidative chemical reaction processes and mechanism on SiC surface and interfaces within the temperature range of 300-2300 K by using reactive molecular dynamics simulation. The oxygen impact on the silica (SiOx) growth of the SiC surface was analyzed, which shows a progressive increase of silica thickness. The simulation results indicated that the oxidation process of SiC was a typical passive oxidation mechanism. With the environmental temperature rising and oxygen impact, the increase of oxidation thickness on the SiC surface undergoes three oxidizing reaction processes: little chemical adsorption of oxygen molecules on the initial surface, rapid oxidation of silicon and carbon, and dramatic oxidation of the interface between the oxidation layer and SiC. Additionally, this work studied the mechanism of oxidation thickness growth and chemical diffusion of oxygen. The oxidation rate is weakened according to the oxygen atom diffusion barrier effect of silica repulsion. Moreover, the kinetic parameters were statistically calculated by fitting the growth of Si-O bonds and their reaction rate constants. Subsequently, the activation energy and pre-exponential factors were derived by using the Arrhenius equation to model the chemical reaction kinetics of the thermal oxidation process. The chemical reaction behaviors of the two stages could be concluded as follows: (i) in stage I, the initial oxidation is reaction rate limiting; (ii) in stage II, SiC oxidation is limited by both the oxidation reaction rate and the oxygen diffusion coefficient of the oxidation layer. The activation energy of stage II increased compared with stage I due to the oxygen atoms diffusion barrier between the oxidation layers. This study on the oxidation and ablation mechanism of the SiC surface at the atomic scale would provide insight into understanding thermal oxidation behavior and the design of ceramic materials.

Восстановление лакового слоя изоляционных пальцев ТЭД с применением установки инфракрасного нагрева камерного типа

Purpose: based on an in-depth analysis of the causes of damage to the insulating fingers of traction motors of electric locomotives, it is necessary to develop a method for increasing their operational reliability. The most effective way to obtain the desired result is to use an improved technology for restoring the electrical insulating varnish layer of insulating fingers using thermoradiation heating. The implementation of a promising technology in depot conditions is possible with the use of a chamber-type infrared heating unit, the control unit of which contains the most optimal energy supply mode determined during experimental studies on a laboratory combined heating unit. Methods: the most significant results of the work were obtained thanks to experimental studies of the electrical and mechanical strength of the cured electrical insulating varnish layer of insulating fingers, in addition, in the process of determining the optimal energy supply mode, finite element modeling methods of thermal processes were used. Results: a design of a laboratory combined infrared heating unit has been developed, thanks to which the optimal drying mode of insulating fingers has been determined, embedded in the operation of an industrial chamber-type unit for drying a set of insulating fingers. Also, the dependence of the breakdown voltage and the hardness of the outer surface of the insulating finger, linking its mechanical and dielectric properties, was determined. Practical significance: the results of the work can be used to improve existing technologies for depot and factory repair of insulating fingers, in particular, to create a series of industrial infrared heating units in locomotive service depots. It is also worth noting that the obtained curve of the dependence of hardness and breakdown voltage, in the future, will allow assessing the electrical strength of insulating fingers indirectly by the hardness parameter of the outer varnish layer.

Ferroelectricity in Ultrathin HfO2-Based Films by Nanosecond Laser Annealing.

Nonvolatile memory devices based on ferroelectric HfxZr1-xO2 (HZO) show great promise for back-end integrable storage and for neuromorphic accelerators, but their adoption is held back by the inability to scale down the HZO thickness without violating the strict thermal restrictions of the Si CMOS back end of line. In this work, we overcome this challenge and demonstrate the use of nanosecond pulsed laser annealing (NLA) to locally crystallize areas of an ultrathin (3.6 nm) HZO film into the ferroelectric orthorhombic phase. Meanwhile, the heat induced by the pulsed laser is confined to the layers above the Si, allowing for back-end compatible integration. We use a combination of electrical characterization, nanofocused scanning X-ray diffraction (nano-XRD), and synchrotron X-ray photoelectron spectroscopy (SXPS) to gain a comprehensive view of the change in material and interface properties by systematically varying both laser energy and the number of laser pulses on the same sample. We find that NLA can provide remanent polarization up to 2Pr= 11.6 μC/cm2 in 3.6 nm HZO, albeit with a significant wake-up effect. The improved TiN/HZO interface observed by XPS explains why device endurance goes beyond 107 cycles, whereas an identical film processed by rapid thermal processing (RTP) breaks already after 106 cycles. All in all, NLA provides a promising approach to scale down the ferroelectric oxide thickness for emerging HZO ferroelectric devices, which is key for their integration in scaled process nodes.

Single activator doped fluoride nanoparticles for X-ray excited high-resolution and delayed flexible nonplanar imaging

Lanthanide doped fluoride nanoparticles (NPs) exhibit adjustable X-ray excited optical/persistent luminescence (XEOL/XEPL) and possessing extensive potential in XEPL-based delay imaging. However, the high-resolution and delayed XEPL-based delay imaging always requires strict introduction of sensitized or heterovalent ions and the construction of complex structures for excellent XEPL performance of lanthanide-doped fluoride NPs, which is attributed to a lack of effective and convenient strategies. Here we show that the intense XEPL strength was obtained by single Tb3+ activated ion doping and simple CsY2F7@NaYF4 core/shell structure for X-ray excited high-resolution and delayed flexible nonplanar imaging. The strict introduction and control of sensitized or heterovalent ions, and the construction of intricate multilayer nanostructure are avoided. In addition, we enable the NPs to achieve high and long-term XEPL performance by simply thermal processing strategy. We successfully mixed minimized amount of the NPs into flexible film to create a scintillation screen which consequently exhibit high surface smoothness, environmental stability, and transparency. Our results demonstrate high resolution delayed imaging of the NPs integrated flexible film for the interior of nonplanar objects. The spatial resolution of 14.3 lp mm−1 is substantially higher than the typical spatial resolutions required for medical CT scans (2 lp mm−1) and X-ray imaging (3.5 lp mm−1). These findings will promote the development of advanced delayed X-ray nonplanar imaging applications.

Use of Flexible Retort Pouch as a Packaging Alternative for Three Mexican Ready-to-eat Bean Products

Objective: This study aimed to design a thermal process for three Mexican bean products packaged on flexible retort pouches and to compare the changes in quality, proximate composition, and antioxidant activity. Method: Three Mexican bean products: “pork beans” (PB), refried beans (RB), and mixed beans (MB, 50% “pork beans” and 50% refried beans), were packaged in retort pouches and processed in a steam/air retort at temperature 122°C, pressure = 2.6 kg·cm-2, come-up time = 13.5 min and 40 min of process, under overpressure conditions. Additionally, nine samples of each bean product packaged in plastic containers of 500 mL were added from the manufacturer's regular hot-fill processing line to be analyzed as control tests. Parameters of quality in all the products were evaluated. Research results and discussions: The Fo values were 13.2, 13.5, and 11.3 min for PB, RB, and MB, respectively. The beans thermally processed showed better protein, fiber, total phenolic, and essential minerals than traditional treatment, were viable, and did not need refrigerated storage. Research implications: The study of thermal processes in heat-resistant pouches in three types of ready-to-eat beans is a healthy and nutritious food alternative. Originality/Value: This study contributes to the development of sterilized foods safe by adjusting the temperature and process time to a Fo value that guarantees the destruction of Clostridium botulinum, with less impact on the final quality of the processed food.

Combining SSVD and subsequent heat treatment processes to fabricate high-quality CsPbBr3 perovskite films

Perovskites, known for their excellent photoluminescence efficiency and color purity, have seen widespread application in flat panel displays and lighting in recent years. Here, we present a process for fabricating CsPbBr3 perovskite film (PeFilm) with high luminescent properties and remarkable weather resistance. By combining single-source vapor deposition (SSVD) with subsequent heat treatment, the quality of PeFilms has been significantly improved. We enhanced the quality of PeFilms by using a thermal annealing process to remove PbBr2 from CsPb2Br5. During annealing, PbBr2 evaporates from PeFilms, changing the crystal phase to CsPbBr3. The heat treatment rearranges atoms between grains, promoting grain growth and fusion, producing larger crystals and reducing defects. The research results demonstrate that the integration of SSVD and appropriate heat treatment enables the fabrication of the CsPbBr3 PeFilm with an emission wavelength of 533 nm, CIE coordinates of (0.1842, 0.7797), and a photoluminescence quantum yield (PLQY) of 52.1%, and even after storing it in atmospheric conditions for 100 days, the PLQY of the CsPbBr3 PeFilm remains above 52%, demonstrating excellent stability.

Effect of moisture content on pyrolysis product yield from lignite and lignite-peanut shell mixtures using slow pyrolysis

ABSTRACT The conversion of biomass-coal mixtures into energy using thermal conversion systems offers a more environmentally sustainable alternative to conventional coal consumption. A reactor with an internal compartment is proposed to improve the pyrolysis performance of lignite coal and mixtures of lignite coal with peanut shells. The study investigates lignite coal with varying moisture contents and peanut shell proportions (0%, 10%, 25%, and 50%) at a temperature of 500°C, using a heating rate of 0.1°C/s. The results indicated that dry mixtures demonstrated higher overall productivity compared to wet mixtures, particularly in terms of charcoal production. The weight of charcoal increased by 4.83%, 4.71%, 4.02%, and 2.61% across the mixtures. The total conversion rates for dry mixtures were 24.59%, 29.27%, 34.36%, and 40.44%, while for wet mixtures, the conversion rates were 29.42%, 33.98%, 38.38%, and 43.05%, respectively. The results revealed that moisture content during pyrolysis significantly influenced the productivity of lignite and lignite-peanut shell mixtures. The conversion rates in dry mixtures were lower compared to those in wet mixtures. The novelty of this work lies in its pioneering investigation of the impact of moisture on the slow pyrolysis of Turkish lignite mixed with peanut shells. It offers novel insights into optimizing the thermal conversion process for these materials by uniquely examining the effects of moisture on productivity and conversion rates.

In Situ Conductive Heating for Thermal Desorption of Volatile Organic-Contaminated Soil Based on Solar Energy

A novel conductive heating method using solar energy for soil remediation was introduced in this work. Contaminated industrial heritage sites will affect the sustainable development of the local ecological environment and the surrounding air environment, and frequent exposure will have a negative impact on human health. Soil thermal desorption is an effective means to repair contaminated soil, but thermal desorption is accompanied by a large amount of energy consumption and secondary pollution. Therefore, a trough solar heat collection desorption system (TSHCDS) is proposed, which is applied to soil thermal desorption technology. The effects of different water inlet temperature, water inlet velocity and soil porosity on the evolution of soil temperature field were discussed. The temperature field of contaminated soil can be numerically simulated, and a small experimental platform is built to verify the accuracy of the numerical model for simulation research. It is concluded that the heating effect is the best when the water entry temperature is the highest, at 70 °C, and the temperature of test point 4 is increased by 50.71% and 1.42%, respectively. When the inlet water flow rate is increased from 0.1 m/s to 0.2 m/s, the heating effect is significantly improved; when the inlet water flow rate is increased from 0.5 m/s to 1.5 m/s, the heating effect is not significantly improved. Therefore, when the flow rate is greater than a certain value, the heating effect is not significantly improved. The simulation analysis of soil with different porosity shows that larger porosity will affect the thermal diffusivity, which will make the heat transfer effect worse and reduce the heating effect. The effects of soil temperature distribution on the removal of petroleum hydrocarbon C6–C9 and trichloroethylene (TCE) were studied. The results showed that in the thermal desorption process of petroleum hydrocarbon C6–C9-contaminated soil, the removal rate of pollutants increased significantly when the average soil temperature reached 80 °C. In the thermal desorption of trichloroethylene-contaminated soil, when the thermal desorption begins, the soil temperature rises rapidly and reaches the target temperature, and a large number of pollutants are removed. At the end of thermal desorption, the removal of both types of pollutants reached the target repair value. This study provides a new feasible method for soil thermal desorption.

Evaluation of heat transfer enhancement effect at the hot/cold end of a Stirling engine using performance improvement factor

The driving force of a Stirling engine comes from the heating expansion and cooling compression of working medium. The enhancement of heat transfer capacity of the hot/cold end is the key to improve the Stirling engine performance, while how to objectively evaluate the heat transfer enhancement effect is a precondition. Herein, a polytropic model of a Stirling engine thermal cycle process was firstly established. A method for evaluating the heat transfer enhancement performance under oscillating flow was proposed based on the efficiency and power improvement of a Stirling engine. This method was further used to evaluate the heat transfer enhancement effect of a novel four-leaf helical heating tube under oscillating flow, the efficiency and power improvement factor of which was reached 13.5 % and 6.1 %, respectively. The results show that the efficiency and power improvement evaluation criterion was more comprehensive and intuitive in evaluating the heat transfer enhancement performance under oscillating flow compared with the conventional evaluation indictor like performance evaluation criterion and equivalent tube length and tube number criterion.

Innovative simplified approach and numerical investigation for flow and heat transfer in internally threaded tubes

Internally threaded tubes exhibit exceptional heat transfer capabilities, holding paramount significance in enhancing energy efficiency, reducing energy consumption, and tackling thermal challenges across aerospace, automotive, and environmental domains. Nonetheless, their intricate structural features, software modelling intricacies, extensive grid requirements, and challenges in maintaining grid quality render numerical simulation investigations a demanding endeavor. This study elucidates the influence mechanisms of thread spacing on the distribution of single-phase and two-phase flows. It delves into the condensation heat transfer of the R32 refrigerant and the single-phase heat transfer of water within internally threaded tubes. At the same Reynolds number, the heat transfer rate can be improved by approximately 19.61% with the optimized internally threaded parameters. When the Reynolds number varies from 18,626 to 51,222, the heat transfer rate per unit length for Tube-5 remains around 2,478.9 W/m, with a variation of less than 5.19%. Furthermore, it presents a simplified numerical simulation approach tailored for internally threaded pipes. This method manipulates wall roughness and regulates wall rotation speed to mimic fluid dynamics phenomena akin to conventional numerical simulation techniques. The findings reveal that the proposed simplified numerical simulation approach yields heat transfer and pressure drop predictions with less than 3% discrepancies compared to traditional numerical simulation predictions. Simultaneously, compared to directly simulating threaded pipes through conventional means, this approach significantly mitigates grid generation complexities, slashing computational time costs by at least 85% and facilitating efficient thermal design and structural optimization processes.

Self-similar solution for laminar bubbly flow evolving from a vertical plate

The development of a bubble plume from a vertical gas-evolving electrode is driven by buoyancy and hydrodynamic bubble dispersion. This canonical fluid mechanics problem is relevant for both thermal and electrochemical processes. We adopt a mixture model formulation for the two-phase flow, considering variable density (beyond Boussinesq), viscosity and hydrodynamic bubble dispersion. Introducing a new change of coordinates, inspired by the Lees–Dorodnitsyn transformation, we obtain a new self-similar solution for the laminar boundary layer equations. The results predict a wall gas fraction and gas plume thickness that increase with height to the power of 1/5 before asymptotically reaching unity and scaling with height to the power 2/5, respectively. The vertical velocity scales with height to the power of 3/5. Our analysis shows that self-similarity is only possible if gas conservation is entirely formulated in terms of the gas specific volume instead of the gas fraction.

Carbon footprints of incineration, pyrolysis, and gasification for sewage sludge treatment

Thermal technologies have gained increasing attention in sludge management. This study applied life cycle assessment to assess the impacts to climate change of ten technological configurations (TCs) treating sludge with incineration, gasification, and pyrolysis. We used distributions of process parameters for quantifying the associated uncertainties and considered different energy exchanges. In a 55 %-fossil energy system, the TCs with various thermal processes showed impacts to climate change in a wide range of −2000 to 2000 kg CO2 eq/t total solid. A probabilistic comparison indicated that with a 10 %-fossil energy system, TCs with gasification and pyrolysis showed a > 95 % probability of performing better than TCs with incineration. Energy consumption and dewatering parameters contributed significantly to the uncertainty due to their large variation and sensitivity. This study emphasized the potential of optimizing key parameters and provided evidence from a climate change perspective for better technological selection and development in sludge management.

Removing Homocoupling Defects in Alkoxy/Alkyl‐PBTTT Enhances Polymer:Fullerene Co‐Crystal Formation and Stability

AbstractC14‐alkoxy/alkyl PBTTT‐OR‐R, a derivative of the prototype PBTTT polymer, is relevant for optoelectronic applications because it combines PBTTT‐like intercalation behavior with enhanced charge‐transfer absorption at longer wavelengths. Additionally, fundamental insights are achieved by comparing this alternating conjugated polymer in the presence and absence of homocoupling defects. While the homocoupling‐free oxidative variant, PBTTT‐OR‐R(O), as well as the Stille polymer with 19% homocoupling defects, PBTTT‐OR‐R(S), can both form co‐crystals when stoichiometrically mixed with PC61BM, the co‐crystal of the latter shows properties which are highly dependent on the thermal processing conditions because of the presence of these defects. The PBTTT‐OR‐R(S):PC61BM co‐crystal shows a low thermal stability and PC61BM can progressively be expelled upon heating. In cooling from the melt and depending on the cooling rate, mixtures of PBTTT‐OR‐R(S) and PC61BM show a competition between co‐crystallization (fast cooling) and separate crystallization (slow cooling). The PBTTT‐OR‐R(O):PC61BM co‐crystal is much more stable up to at least 260 °C and is not influenced by the applied cooling rate. These findings also translate to the device level. The performance of PBTTT‐OR‐R:PC61BM photodiodes is severely deteriorated after isothermal annealing in case of PBTTT‐OR‐R(S), whereas the thermally robust co‐crystals of PBTTT‐OR‐R(O) allow a more flexible design of optimized devices.

Comparison of acidified and conventional low acid thermal processing of white mushroom in glass jars as influenced by reciprocating agitation

The objective of this study was to evaluate the quality advantage that can be gained by combining acidified low-acid food thermal processing (ALTP) (pH < 4.6) and reciprocating agitation thermal processing (RATP) of mushroom. Mushroom was selected as a low acid food which is conventionally subjected to low-acid food conventional thermal processing (LACP) (pH > 4.6). Glass jars were used as containers. LACP was established to target a commercial sterilization process (Fo value of 5.0 min at 121.1 °C), while ALTP was established to get an equivalent pasteurization process (Fo value of 10.0 min at 90 °C). Heat penetration data was obtained to establish the above targeted processes and to assess the influence of processing conditions on the heating rate index and heating lag factor. Once processed, the associated quality parameters were evaluated and compared. Process variables included three processing temperatures (115, 120, 125 °C for LACP and 90, 95 and 100 °C for ALTP) and three RATP conditions (0, 1.0 and 2.0 Hz agitation). The results revealed higher rates of heat penetration and lower processing times for both LACP and ALTP processes as the reciprocation frequency increased. Quality retention advantages were realized as the process temperature was increased in each case. The best advantage was delivered with ALTP. Although the rate of heat transfer was the highest at 2.0 Hz, the best quality was observed at a moderate agitation frequency (1.0 Hz) as product texture breakdown was avoided. This is the first study that combined ALTP and RATP and compared them with LACP.

Cold plasma processing of kiwifruit juice: Effect on physicochemical, nutritional, microstructure, rheological properties and sensory attributes.

This study aimed to compare the untreated, cold plasma (CP)-optimized (30 kV/5 mm/6.7 min), CP-extreme (30 kV/2 mm/10 min), and thermally treated (TT) (90 ℃/5 min) kiwifruit juices based on the physicochemical (pH, total soluble solids (TSS), titratable acidity (TA), total color change (ΔE)), physical (particle size and rheology), microstructure (optical microscope), bioactive compounds (polyphenol, ascorbic acid, and sugar compounds), and sensory characteristics of kiwifruit juice. The pH, TSS, and TA were not significantly affected in CP and TT juice, whereas the ΔE (6.52) of TT juice lies in the range of "greatly visible." The microstructure characteristics of juice significantly changed after CP and thermal treatment. The cell and tissue disruption in CP-extreme and thermally treated juice was more than CP-optimized. The particle size of juice decreased irrespective of treatment, but the span value of CP-optimized juice was the lowest. Further, the CP treatment showed a lower consistency index, apparent viscosity, and pseudoplasticity of juice than the thermal treatment. The CP-treated juice retained bioactive and nutritional attributes more than thermally treated juice. The CP-optimized, CP-extreme, and thermal treatment reduced the sucrose content by 54, 55, and 23%, while the fructose and glucose content were increased by 17, 12, & 93%, and 17, 11 & 99%, respectively. Among the CP-treated juice, CP-optimized (71.36 mg/100g) contained a higher amount of ascorbic acid than the CP-extreme (64.36 mg/100g). Based on the similarity values in the fuzzy logic analysis, the sensory attributes of CP-optimized treated juice were superior to CP-extreme and thermal treated. PRACTICAL APPLICATION: In this era, non-thermal processing techniques are trending for retaining the nutrition and stability of juice. The old plasma (CP)-treated kiwifruit juice had better nutritional, bioactive compounds, and sensory attributes than the thermally treated juice. Further, the CP-treated juice had higher flowability and lower viscosity, making it ideal for juice processing. The conclusions drawn suggest that CP processing is a better alternative for processing kiwifruit juice than thermal processing.