Moderate Heat Treatment Research Articles

Optimization of co-linear-type pulsed electric field treatment chamber for milk pasteurization

Pulsed electric fields (PEFs) are increasingly employed industrially as pasteurization methods for liquid foods. However, some issues regarding heat-sensitive, high-protein liquid foods remain unresolved. The efficacy of PEFs during continuous processing depends on the structural characteristics of the processing chamber. This study presents the optimal structure of our originally developed colinear-type PEF treatment chamber, determined through a combination of experimental and numerical calculations. Our pasteurization system, with a flow rate of 10 L/h, involved an optimized PEF treatment and a moderate heat treatment at 60 °C. Our system inactivates Listeria innocua in sterilized milk by more than seven orders of magnitude. In a durability test, the system was successfully operated continuously for more than 1 h under pasteurized conditions without any damage or component adhesion on the stainless-steel electrodes. This study provides guidelines for the high-flow pasteurization of high-protein liquid foods.

Modulation of Interlayer Nanochannels via the Moderate Heat Treatment of Graphene Oxide Membranes.

In response to the phenomenon of interlayer transport channel swelling caused by the hydration of oxygen-containing functional groups on the GO membrane surface, a moderate heat treatment method was employed to controllably reduce the graphene oxide (GO) membrane and prepare a reduced GO composite nanofiltration membrane (mixed cellulose membrane (MCE)/ethylenediamine (EDA)/reduced GO-X (RGO-X)). The associations of different heat treatment temperatures with the hydrophilicity, interlayer structure, permeability and dye/salt rejection properties of GO membranes were systematically explored. The results indicated that the oxygen-containing groups of the GO membrane were partially eliminated after heat treatment, and the hydrophilicity was weakened. This effectively weakened the hydration between the GO membrane and the water molecules and inhibited the swelling of the oxidized graphene membrane. In the dye desalination test, the MCE/EDA/RGO membrane exhibited an ultra-high rejection rate of over 97% for methylene blue (MB) dye molecules. In addition, heat treatment increased the structural defects of the GO membrane and promoted the fast passage of water molecules via the membrane. In pure water flux testing, the water flux of the membrane remained above 46.58 Lm-2h-1bar-1, while the salt rejection rate was relatively low.

Intraspecific variation in responses to extreme and moderate temperature stress in the wild species, Solanum carolinense (Solanaceae).

Adaptation or acclimation to local temperature regimes has often been used as a proxy for predicting how plant populations will respond to impending novel conditions driven by human-caused climate change. To understand how plants may successfully respond to increasing air temperatures (extreme and moderate) in the future, we explored how temperature tolerance traits differ in populations of Solanum carolinense from northern (MN) and southern (TX) regions of the continental USA in a two-experiment study. In the first experiment, we compared the heat and cold tolerance in vegetative (sporophyte) and reproductive (male gametophyte) traits. In the second experiment, we studied if long-term heat influences plant development by examining how development in moderate heat affected reproductive structures and reproductive success. We found that temperature sensitivity differed between southern populations, which regularly experience extreme heat, and northern populations which do not. In contrast to our expectations, northern populations appeared more heat-tolerant than southern populations for vegetative traits such as chlorophyll stability and reproductive traits such as pollen germination. Our results are consistent with a heat-avoidance, rather than tolerance mechanism to mitigate extreme heat during pollen germination. In the second experiment, plants developing under the moderate heat treatment had significantly smaller reproductive structures and reduced seed production (27% fewer seeds on average than in the control treatment). Reproductive structures that developed in moderate heat were also reduced in size, particularly in the northern populations relative to populations from the south. We conclude that rising temperatures have the potential to incur substantial negative consequences for the reproductive success of individuals in this species and that some populations already mitigate stressful temperature conditions through phenotypic plasticity.

Synthesis and Exploration of Barium Stannate-Zirconate BaSn1-xZrxO3 (0 ≤ X ≤ 1) Solid Solutions as Photocatalysts.

Employing ionic liquid-assisted microwave synthesis and moderate heat treatment allows for the preparation of otherwise difficult-to-obtain perovskite-type BaSn1-xZrxO3 solid solutions (0 ≤ x ≤ 1). The impact of substituting Sn for the crystal structure, crystallinity, morphology, and photocatalytic performance was investigated. The obtained materials are characterized by X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller (BET) surface area analysis, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, and Raman and IR spectroscopy. SEM images show that the morphology of the samples varies from rods for x = 0, 0.2 to spherical for x = 0.5, 0.8, 1. Upon Zr for Sn substitution, the band gap changes from 3.1 to 5.0 eV as the valence and conduction bands move to lower and higher energies. The photocatalytic activities of the BaSn1-xZrxO3 samples in the hydroxylation of terephthalic acid (TA) follow the order BaSn0.5Zr0.5O3> BaSn0.8Zr0.2O3> BaSnO3> BaSn0.2Zr0.8O3> BaZrO3. The superior photocatalytic activity of BaSn0.5Zr0.5O3 can be attributed to the synergistically favorable combination of a suitable band structure, band gap size, and increased surface area-to-volume ratio, resulting in a diminished crystalline particle size unattainable from samples prepared via traditional synthetic routes or without ionic liquid.

Experimental investigation on cold-formed steel hollow sections with moderate heat treatment under combined compression and cyclic lateral loads

This paper presents an experimental investigation on cold-formed steel rectangular and square hollow sections (RHSs and SHSs) with subsequent heat-treatment under combined compression and cyclic lateral loads. A total of 25 specimens designed with different parameters, including slenderness ratios (b/t and d/t) and axial load ratio (n) ranging from 0 to 0.5 were tested. Material tests were carried out to confirm the material ductility requirements stated in Eurocode being reached. Failure modes, moment-rotation curves, secant stiffness, energy dissipation and plastic hinge length presented were analysed. In addition, deformation capacity was evaluated in terms of maximum and ultimate rotations. The comparison results between plastic rotation limits proposed by design codes and the test results indicate that AISC 341-16 is more suitable for the design of cold formed hollow sections with moderate heat treatment under this investigation, though the recommended reduction factor of axial load might be conservative.

Effects of heat treatment on the profile of volatile flavor components in bamboo shoots

The effects of different heat treatment conditions (105, 110, and 120 °C; 10, 20, 30, 40, and 50 min) on the flavor profiles of bamboo shoots were investigated using headspace/solid-phase microextraction-gas chromatography/mass spectrometry/olfactometry-odor activity value (HS/SPME-GC/MS/O-OAV) and sensory analysis. Results indicated noticeable differences in the amount and rate of changes in both original and newly produced flavor components in bamboo shoots at different temperatures. The retention rates of hexanal at 105 °C, 110 °C, and 120 °C were 8.55–34.41%, 7.28–34.32%, and 5.22–11.08%, respectively, whereas (E)-2-hexenal, (E, E)-2,4-heptadienal, (E, Z)-2,6-nonadienal, 1-hexanol, 1-octen-3-ol and 2-pentylfuran were mostly lost after heat treatment. The content of three lipid oxidation compounds (octanal, nonanal, and decanal) increased 75.59–500.67%, while the content of newly generated Maillard reaction compounds (e.g. methional, furfural) increased (0–12.58 μg/kg) with heating temperature and time. Sensory analysis indicated that the bamboo shoots heated at 110 °C for 30 min had the best overall flavor. These findings suggested that moderate heat treatment could eliminate some grassy and mushroom flavors from bamboo shoots, enhancing their sweet flavor. This improvement could be favorable for the consumer acceptance of heat-processed bamboo shoots.

Effect of UV-C Radiation and Thermal Treatment on Volatile Compounds, Physicochemical, Microbiological and Phytochemical Parameters on Apple Juice (Malus domestica) with Raspberry (Rubus idaleus L.)

Volatile compounds contribute to aroma and flavor, these being the main sensory attributes in food acceptance. This work addresses the physicochemical, volatile compounds, polyphenols, and flavonoids content and, antioxidant activity of apple-raspberry (90/10%) juice treated by thermal and ultraviolet radiation (UV-C) alone or in combination with moderate heat-treatment. Nineteen volatile compounds were identified which experienced changes depending on the treatment. Compounds such as α-ionone and β-ionone, that contribute to raspberries characteristic aroma, were present in a greater concentration in the UV-C treatment and lower in the thermal treatment. Likewise, 2-methyl butyl acetate, which give a fruity-sweet aroma typical of apples was present in a greater concentration in the UV-C treatment. Regarding polyphenol content, control and combined treatment presented the greater concentrations. However, after twenty days of storage, control and combined treatment presented the lower flavonoid concentration. Nevertheless, at this time, treatments showed no variations in antioxidant activity. Yeast and mold and total aerobic mesophilic and psychrophilic counts were reduced in the heat and combined treatments. In conclusion, UV-C and moderate heat might successfully be used to process a stable apple-raspberry juice while maintaining its quality and safety.

Influence of Hot Rolling Practice and Furnace Residence Time on the Strength and Toughness of Normalised Nb-Ti-V Structural Steel Plate

The influence of moderate thermomechanical rolling and heat treatment time on the microstructure and mechanical properties of normalised Ni-containing Nb-Ti-V microalloyed plate steels was investigated. Conventional rolling (CR) and low austenitic temperature rolling (TM) schedules were applied to 25 and 55mm thick plates. Predicted plate thermal profiles were used to simulate normalising of 25 and 55mm thick plates at the mid-thickness. As expected, the microstructure after TM rolling was finer due to austenite sub-structure development below the no-recrystallisation temperature which increases the amount of ferrite nucleation sites. The tensile strength of the CR plates was generally higher due to a larger pearlite volume fraction resulting from slow cooling from a relatively coarse austenite. In 25mm plate, the presence of acicular ferrite after CR resulted in a higher yield strength than that obtained after TM rolling. Furnace residence times of 0.75min/mm and longer allowed for plates to be completely normalised – characterised by continuous, well-defined polygonal ferrite grain boundaries. Short furnace residence times restricted the plate temperature to below the end of the ferrite-to-austenite transformation (Ac3), where untransformed ferrite is retained from the as-rolled microstructure and is characterized by poorly defined grain boundaries. Rolling practice and normalising residence time had little to no effect on impact toughness, but significantly influenced the normalised yield strength of thicker plate.

Evaluation of the additive effects of volatile fatty acids and moderate heat treatment for enhancing the inactivation of vegetative cells and spores of Clostridium perfringens by flow cytometry

ObjectivesClostridium perfringens is a well-known spore-forming bacterium that can resist the environment. A mixture of volatile fatty acids or thermal treatments can interact with these bacteria. The aim of this study was to evaluate the effects of different volatile fatty acid concentrations and moderate heat treatment on Clostridium perfringens sporulation. MethodsA pure culture of Clostridium perfringens type A in Duncan Strong medium was treated with a mixture of volatile fatty acids at several concentrations. A thermal treatment was also tested. To evaluate the effects, a double staining method was employed, and treatments on Clostridium perfringens were analysed by flow cytometry. ResultsModerate heat treatment destroyed vegetative forms but had no effect on sporulating forms. Volatile fatty acids combined with moderate heat treatment inhibited Clostridium perfringens sporulation. ConclusionsThe use of flow cytometry as an original method for evaluating the treatment of Clostridium perfringens is of interest because of its simplicity, short time to obtain results, and the level of information provided on the microbial population (impact on metabolism). A combination of mild treatments (moderate heat treatment + volatile fatty acids) to decrease the Clostridium perfringens concentration when these bacteria sporulate is a very promising finding for inhibiting Clostridium perfringens propagation.

Effect of moderate Fe doping and heat treatment on the microstructure of Ni-Mn-Ga melt-spun ribbons

The present work investigates the effects of Mn substitution with additions of Fe (0.5, 1, 2, and 3 at%) on the crystal structure, phase transformation temperatures, and magnetic properties of casted and heat-treated Ni49.8Mn28.5−xGa21.7Fex magnetic shape memory (MSM) alloys. The alloys doped with 0.5 and 1 at% Fe exhibited single-phase seven-layered modulated (14 M) and five-layered modulated (10 M) martensite structures at ambient temperature, whereas the alloys doped with 2 and 3 at% Fe exhibited L21 Heusler austenite structures at ambient temperature. The Ni49.8Mn27.5Ga21.7Fe1 alloy exhibiting the 10 M crystal structure at ambient temperature was selected for making ribbons using the melt-spinning process. The effects of heat treatment on grain growth, crystal structure, and other functional properties of the melt-spun ribbons were studied. The ribbons heat-treated at 1273 K exhibited a 10 M martensite structure and an average grain size of 220 µm along the ribbon plane. The results show that Ni49.8Mn27.5Ga21.7Fe1 is a particularly promising composition for designing and manufacturing functional MSM micro-actuators.

Reversible and irreversible effects of a moderate heat treatment on the moisture sorption and swelling behavior of modern and historical oak wood

Reversible and irreversible effects of a moderate heat treatment on the moisture sorption and swelling behavior of modern and historical oak wood

The effect of heat treatment on the lactosylation of milk proteins

Protein lactosylation is a significant modification that occurs during the heat treatment of dairy products, causing changes in proteins' physical-chemical and nutritional properties. Knowledge of the detailed lactosylation information on milk proteins under various heat treatments is important for selecting appropriate thermo-processing and identifying markers to monitor heat load in dairy products. In the present study, we used proteomics techniques to investigate lactosylated proteins under different heating temperatures. We observed a total of 123 lactosylated lysines in 65 proteins, with lactosylation even occurring in raw milk. The number of lactosylated lysines and proteins increased moderately at 75°C to 130°C, but dramatically at 140°C. We found that 6 out of 10, 9 out of 16, 6 out of 12, and 5 out of 15 lysine residues in κ-casein, β-lactoglobulin, α-lactalbumin, and αS1-casein, respectively, were lactosylated under the applied heating treatment. Moreover, different lactosylation states of individual lysines and proteins can indicate the intensity of heating processes. Lactosylation of K14 in β-lactoglobulin could distinguish pasteurized and UHT milk, while lactosylation of lactotransferrin can reflect moderate heat treatment of products.

Heated and unheated lupin protein‐grape seed extract conjugates stabilizing and structuring high internal phase oil‐in‐water emulsions

AbstractPlant‐based high internal phase oil‐in‐water emulsions (HIPEs) are promising fat replacers. However, producing stable HIPES with improved viscoelastic properties is a challenge for the food industry. Conjugation of plant proteins, such as lupin protein isolate, with phenolic compounds, such as proanthocyanidins from grape seed extract, associated (or not) with moderate heat treatment arise as potential methods to tune the surface properties of proteins and, consequently, the droplet‐droplet interactions that drive the viscoelastic properties of HIPEs. In this way, unheated (UHC) and heated (85°C, 15 min) (HC) lupin protein (LPI)‐grape seed extract (GSE) conjugates were produced and used to stabilize HIPEs. Evaluation of stability by Turbiscan and oil loss by centrifugation over 56 days of storage did not reflect the kinetic stability of HIPEs against process conditions. Under shearing, UHC‐stabilized emulsions at high GSE concentrations showed oil release, whereas all HC‐stabilized HIPEs released oil. However, the increase in GSE concentration and heat treatment improved the viscosity and storage modulus (G′) of HIPEs, possibly due to the droplet‐droplet interaction originating from hydrophilic and hydrophobic interactions in UHC and HC‐stabilized HIPEs, respectively. This pivotal study confirmed that conjugation of a plant protein with GSE and heat treatment could improve the viscoelastic properties of HIPEs and produce HIPEs with superior texture (higher G′).

Raising the temperature on electrodes for anion exchange membrane electrolysis - activity and stability aspects

The membrane electrode assembly is the powerhouse of the anion exchange membrane water electrolyser (AEMWE), thereby placing a great importance on the associated preparation conditions. This paper investigated how annealing temperature and time impacted activity and stability for both anode and cathode electrodes with catalyst-PTFE thin-films. The effect of annealing was thoroughly characterised through SEM/EDS, TEM, XRD, Raman spectroscopy and XPS. Moderate heat-treatment (T≤500°C) had a positive effect by improving morphology and enhancing reaction kinetics as seen through three-electrode measurements. Annealing temperature affected hydrogen adsorption, resulting in a change in the hydrogen evolution pathway as shown by hydrogen adsorption peaks and Tafel curves. These beneficial effects were further augmented by an enlarged surface area as shown in both three- and two-electrode measurements. Two electrode measurements revealed a staircase activity-trend, where the annealing temperature yielding the greatest activity declined with increasing annealing time. This resulted in efficient cathodes annealed at 2h-500°C, 3h-400°C and 4h-300°C. The aforementioned cell configurations reached approximately 500 mA cm−2 at 1.73 V, 1.82 V and 2.04 V respectively. Stable electrodes were produced for temperatures ≤500°C, after which their mechanical integrity began to fail due to pyrolysed PTFE. Stability was meticulously characterised and a degradation pathway for carbon catalysts was proposed, where expansion of the carbon black onion layers ultimately lead to catalyst particle detachment.

Probing the incoherent admixture of low and high-spin states of Co in (LaPr)CoO3 perovskite: focus on structural phase transitions

We report the mixed valence and intermediate spin-state (IS) transitions in Pr substituted LaCoO3 perovskites in the form of bulk and nanostructures. Various compositions (x) of La1−x Pr x CoO3 (0 ⩽ x⩽ 0.9) were synthesized using the sol–gel process under moderate heat treatment conditions (600 °C). The structural analysis of these compounds reveals a phase crossover from the monoclinic phase (space group, s.g.: I2/a) to an orthorhombic one (s.g.: Pbnm), and a rhombohedral phase (s.g.: R-3c) to an orthorhombic one (s.g.: Pnma) in the bulk and nanostructures, respectively, for the composition range 0 ⩽ x⩽ 0.6. Such a structural transformation remarkably reduces the Jahn–Teller distortion factor ΔJT: 0.374 → 0.0016 signifying the dominant role of the IS state (S Avg = 1) of trivalent Co ions in the investigated system. Magnetization measurements reveal the ferromagnetic (FM) nature of bulk LaCoO3 along with a weak antiferromagnetic (AFM) component coexisting with an FM component. This coexistence results in a weak loop-asymmetry (zero-field exchange-bias effect ∼134 Oe) at low temperatures. Here the FM ordering occurs due to the double-exchange interaction (J EX /k B∼ 11.25 K) between the tetravalent and trivalent Co ions. Significant decrease in the ordering temperatures was noticed in the nanostructures (T C ∼ 50 K) as compared to the bulk counterpart (∼90 K) due to the finite size/surface effects in the pristine compound. However, the incorporation of Pr leads to the development of a strong AFM component (J EX/k B ∼ 18.2 K) and enhances the ordering temperatures (∼145 K for x = 0.9) with negligible FM correlations in both bulk and nanostructures of LaPrCoO3 due to the dominant super-exchange interaction: Co3+/4+‒O‒Co3+/4+. Further evidence of the incoherent mixture of low-spin (LS) and high-spin (HS) states comes from the M–H measurements which yields a saturation magnetization of M S ∼ 275 emu mol−1 (under the limit of 1/H → 0) consistent with the theoretical value of 279 emu mol−1 corresponding to the spin admixture: 65% LS + 10% IS of trivalent Co along with 25% of LS Co4+ in the bulk pristine compound. A similar analysis yields: Co3+ [30% LS + 20% IS] + Co4+ [50% of LS] for the nanostructures of LaCoO3, yet the Pr substitution decreases the spin admixture configuration. The Kubelka–Munk analysis of the optical absorbance results in a significant decrease in the optical energy band gap (E g:1.86 → 1.80 eV) with the incorporation of Pr in LaCoO3 which corroborates the above results.

Various electromagnetic properties of magnetic Fe-based nanorods in GHz range

The introduction of magneto-dielectric substrates is required in the micro-strip antennas miniaturization due to the various dielectric and permeability constant. Most research work focus on the spherical structural Fe nanomaterials and the nanorods structures are rarely synthesized. In this paper, Fe-based nanorods have stepwise been synthesized with well maintaining their size and morphology by a moderate heat treatment of α-FeOOH nanorods. The magnetic and electromagnetic properties above GHz have been investigated. It is found that α-FeOOH, β-FeOOH and α-Fe2O3 nanorods have a constant real part of permittivity and low loss tangent tan δε. And the γ-Fe2O3, Fe3O4, and Fe nanorods are observed a resonance peak at 3 GHz which is over their nature resonance frequency and a relatively large permeability than their spherical nanoparticles. Our results indicate that Fe-based nanorods have various permittivity and permeability properties which have great potential application in high-frequency electronic or spintronic devices.

Investigating the OSL components and the sensitivity changes in a natural quartz crystal showing an intense post-sensitization TL signal

This study aims to investigate the optically stimulated luminescence of quartz grains exhibiting an intense thermoluminescent signal between 250 and 350°C after sensitization with a high dose of gamma radiation and moderate heat treatments. Pellet discs produced with zeroed and sensitized grains were irradiated with test doses ranging from 0.5 to 40 Gy. After sensitization, the OSL signal of the fast component stimulated with blue light increased more than 1000 times. Annealing at 400°C was adopted to erase the residual signal. The sensitivity changes were assessed after various TL and OSL readings. The annealing cycles were responsible for a significant increase in OSL and a 20% reduction in TL signals. The analysis of the residual TL indicated that the traps responsible for the main components of the sensitized peak (280°C) are harder to bleach than those related to the so-called 110, 325, and 375°C peaks. The sensitivity changes and the relationship between OSL and TL signals were explained in terms of a mechanism of competition involving active and deep electron traps. No correlation was observed between the fast OSL component and the 325°C TL peak.

Amitraz and Its Metabolites: Oxidative Stress-Mediated Cytotoxicity in HepG2 Cells and Study of Their Stability and Characterization in Honey.

The population decrease of bees that has been observed in recent years due to the Varroa destructor parasite may endanger the production of bee-products whose demand is on the rise. To minimize the negative effects caused by this parasite, the pesticide amitraz is commonly used by beekeepers. Based on these, the objectives of this work are to determine the toxic effects caused by amitraz and its metabolites in HepG2 cells, as well as its determination in honey samples and the study of its stability with different heat treatments commonly used in the honey industry and its relationship with the amount of 5-hydroxymethylfurfural (HMF) produced. Amitraz significantly decreased cell viability by MTT assay and total protein content (PC) assay, being more cytotoxic than its metabolites. Amitraz and its metabolites caused oxidative stress by Lipid Peroxidation (LPO) production and Reactive Oxygen Species (ROS) generation. Residues of amitraz and/or its metabolites were found in analyzed honey samples, with 2,4-Dimethylaniline (2,4-DMA) being the main metabolite confirmed by high-performance liquid chromatography-high resolution mass spectrometry (HPLC-QTOF HRMS). Amitraz and its metabolites resulted as unstable even at moderate heat treatments. Additionally, a positive correlation in terms of HMF concentration in samples and the severity of heat treatment was also observed. However, quantified amitraz and HMF were within the levels set in the regulation.

Exploring the Power of Thermosonication: A Comprehensive Review of Its Applications and Impact in the Food Industry

Thermosonication (TS) has been identified as a smart remedy for the shortcomings of heat treatment, which typically requires prolonged exposure to high temperatures. This technique combines moderate heat treatment with acoustic energy to eliminate harmful microorganisms and enzymes in food products. Unlike conventional heat treatment, thermosonication utilizes short holding times, allowing for the preservation of food products' phytochemical compounds and sensory characteristics. The benefits and challenges of this emerging technology, such as equipment cost, limited availability of data, inconsistent results, high energy consumption, and scale-up challenges, have been assessed, and the design process for using ultrasound in combination with mild thermal treatment has been discussed. TS has proven to be a promising technique for eliminating microorganisms and enzymes without compromising the nutritional or sensory quality of food products. Utilizing natural antimicrobial agents such as ascorbic acid, Nisin, and ε-polylysine (ε-PL) in combination with thermosonication is a promising approach to enhancing the safety and shelf life of food products. Further research is required to enhance the utilization of natural antimicrobial agents and to acquire a more comprehensive comprehension of their impact on the safety and quality of food products.

Moderate heat treatment of CoFe Prussian blue analogues for enhanced oxygen evolution reaction performance

Moderate heat treatment of CoFe Prussian blue analogues for enhanced oxygen evolution reaction performance