Vacuum Pulse Research Articles

Exploring solution composition and vacuum pulse effects in the osmotic processing of sole (Paralichthys sp.) fillets

The study investigates the osmotic dehydration (OD) of sole fillets and its mass transfer kinetics. Brine (S10), brine+sucrose (S10Az), and brine+sucrose+acetic acid (S10AA) solutions were used, with treatments conducted under atmospheric pressure (control) and with vacuum impregnation pulses (VI) for 7 hours. A positive mass change was observed over time in S10 and S10Az, leading to increased processing yields, while a decreasing trend was noted in S10AA. VI had a significant effect on NaCl content in S10AA, resulting in a 45 % processing time reduction. The Peleg model accurately fitted the solutes content dynamics, suggesting that VI shortens the time it takes to reach equilibrium for NaCl and sucrose. Product texture characteristics were affected by the solution composition, with increased hardness in S10AA, but not by VI treatment. These findings enhance the understanding of fish pre-treatment operational variables and suggest the VI potential for streamlining processes in the fish industry.

Preserving potato perfection: Optimizing innovative drying techniques for maintaining physicochemical attributes and starch structure

To address the limitations of conventional hot air drying (HAD) for potato dehydration, pulsed vacuum drying (PVD) and humidity-controlled HAD (HC-HAD) were proposed as innovative techniques. In PVD, varying vacuum pulse durations (6, 8, 10, 12, and 14 min) and atmospheric pulse durations (2, 3, 4, and 5 min) were investigated. Under HC-HAD, different humidity control scenarios (40,30+30,90+CF, 50,30+30,90+CF, 40,30+CF, and 50,30+CF) were examined. The study revealed that a 14:2 duration pulsing in PVD retained the color and achieved the highest total phenol content (TPC) and antioxidation activity (conserving 97.50 % and 84.67 % of their fresh values, respectively) but had the longest drying time (260.00 min) compared to HC-HAD and HAD (139.45 min). The 50,30+CF strategy of HC-HAD exhibited the quickest drying time (116.79 min), maintained the color, TPC (87.97 % of the fresh value), and antioxidation activity (71.40 % of the fresh value), and achieved the best potato microstructure and starch structure. Furthermore, Artificial Neural Network simulations for HC-HAD conditions demonstrated significant reliability. These findings provide valuable insights for potato researchers and producers seeking to enhance preservation techniques and prolong the shelf life of potatoes as a staple crop.

Production of dry extracts from sea buckthorn raw materials: Research results

Production of soluble dry extracts from sea buckthorn raw materials is relevant and promising for enterprises of the Republic of Buryatia. The authors have selected technological equipment for obtaining dry extracts: extractor, concentrator, dryer. The possibility of using vacuum-pulse action and the influence of technological factors on the yield of water-soluble substances from sea buckthorn leaves and shoots has been studied. The operating parameters of the technological process have been determined experimentally under production conditions: temperature 45–50 °C, total duration of extraction, concentration and drying 79–111 minutes. The process of obtaining dry extracts is carried out in three stages: water extraction; filtration and concentration; drying in a vacuum pulse dryer. The resulting experimental sample of dry extract from sea buckthorn leaves and shoots is a free-flowing crystalline powder with a moisture content of 4–6 %, highly soluble in water, having high organoleptic characteristics – a natural, well-defined aroma characteristic of sea buckthorn, light brown color. The use of low temperatures and vacuum-pulse modes at the stages of the technological process predicts high safety of thermolabile biologically active substances in the product. The process of obtaining dry extracts from sea buckthorn leaves and shoots has been studied. The results of the studies prove the possibility of producing a dry extract with high organoleptic characteristics using the developed by the authors' technology by equipment whose vacuum-pulse operating modes have a positive effect on the yield of extractives and help reduce time costs along with the intensification of heat and mass exchange processes in sea buckthorn raw materials.

Improving preservation of bioactive compounds in mangosteen peel flour through pre-treatment with bleaching, ethanol, and vacuum pulse

One method of utilizing mangosteen peel involves subjecting it to the drying process. Applying different pre-treatments before drying is seen as an alternative to minimize the negative effects of temperature on obtaining flours. The study investigated various pre-treatment methods to enhance the production of mangosteen peel flour (MPF) while preserving its bioactive compounds. Pre-treatments with ethanol (E), blanching (B), and vacuum pulse (V) were used individually and in combination (EV, BE, BV and BEV), followed by convective drying at 80 °C. The obtained flours were evaluated for antioxidant capacity, profile of phenolic compounds and minerals, morphology of particles (SEM), and physical properties. The pre-treated samples showed higher levels of phenolic compounds than the control sample (C), with flavonoids standing out, especially in variants blanched. Samples EV and BEV exhibited high antioxidant capacity. All samples are sources of potassium, copper and zinc. The samples showed irregular particles, with varying sizes, with V, EV, and BEV being smaller and less agglomerated, and the results indicated cohesive properties in MPF. The porosity of the samples was consistent, limiting their flowability. The BEV approach stood out, preserving bioactive components, increasing antioxidant capacity, and proving to be effective in obtaining better MPF.

Surface-Enhanced Raman Spectroscopy of Ammonium Nitrate Using Al Structures, Fabricated by Laser Processing of AlN Ceramic.

This work presents results on laser-induced surface structuring of AlN ceramic and its application in Surface-Enhanced Raman Spectroscopy (SERS). The laser processing is performed by nanosecond pulses in air and vacuum. Depending on the processing conditions, different surface morphology can be obtained. The ablation process is realized by ceramic decomposition as the formation of an aluminium layer is detected. The efficiency of the fabricated structures as active substrates in SERS is estimated by the ability of the detection of ammonium nitrate (NH4NO3). It is conducted for Raman spectrometer systems that operate at wavelengths of 514 and 785 nm where the most common commercial systems work. The obtained structures contribute to enhancement of the Raman signal at both wavelengths, as the efficiency is higher for excitation at 514 nm. The limit of detection (LOD) of ammonium nitrate is estimated to be below the maximum allowed value in drinking water. The analysis of the obtained results was based on the calculations of the near field enhancement at different conditions based on Finite Difference Time Domain simulation and the extinction spectra calculations based on Generalized Mie scattering theory. The structures considered in these simulations were taken from the SEM images of the real samples. The oxidation issue of the ablated surface was studied by X-ray photoelectron spectroscopy. The presented results indicated that laser structuring of AlN ceramics is a way for fabrication of Al structures with specific near-field properties that can be used for the detection of substances with high social impact.

A novel textile drying technique via pulsed vacuum method

Drying is a time-consuming and energy-intensive process linked to environmental thermodynamic properties. Conventional methods often use high temperatures for long durations, potentially harming textiles. This article introduces an innovative vacuum textile drying technique utilizing pressure pulsation. Experimental validation reveals that pulsed vacuum drying (PVD) accelerates drying rates and lowers operational temperatures for cotton samples. Compared to constant vacuum drying, PVD achieves a 23% faster reduction to 5% moisture content while maintaining quality. PVD reduces drying temperature from 80 to 60 °C for the same drying time at atmospheric pressure. This article presents a numerical model to analyze fabric drying properties. Simulation results align with experimental results, with deviations in a range of 10 °C for critical temperatures and 2% for moisture content and drying time. The experimental and computational results helped to identify dryer performance key variables: chamber pressure, temperature, and vacuum pulse modulation. A series of experiments reveal optimized vacuum modulation that enhances average drying rate and minimizes drying time.

Electron acceleration by low order axisymmetric modes of Hermite-Cosh-Gaussian laser pulses in vacuum

Hermite-Cosh-Gaussian (H-ch-G) laser pulse is proposed for effective electron acceleration and energy gain by exploring its low order axisymmetric modes in vacuum. The intensity distribution of H-ch-G laser is influenced by the TEM(m, n) modes ordered Hermite polynomial, decentered parameter (b) controlled Cosh function and Gaussian beam function. The increase in decentered parameter b associated with Cosh function, changes its properties from fundamental Gaussian(b = 0) to more complex Gaussian types with ring-shaped (b ∼ 2) forms. As a result, it operates well enough to quickly accelerate electrons to exceedingly high energies in a short period of time. The laser pulse order TEM00, TEM01 or TEM10 are the low order axisymmetric modes of H-ch-G laser beam. The analytic results show that altering the mode indices (m, n) and decentered parameter (b) combination leads to a remarkable rise in electron energy with laser intensity (∼) to the order of GeV in vacuum.

Radially Polarized Laser-Induced Electron Acceleration in Vacuum

Enhanced electron acceleration due to tightly focused (TF) short-intense radially polarized (RP) Gaussian laser pulse in vacuum has been investigated. An axicon optical lens is utilized to accomplish a TF laser beam. The TF-RP laser fields are truncated to fifth order in diffraction angle. The innate and attractive symmetry of the tightly focused RP laser pulse imposes the trapping of electrons in the route of the laser propagation throughout laser–electron interaction. The applied axial magnetic field further ensures the enhancement in ponderomotive strength, pushing the electron in the expediting phase up to longer distances. Utilizing the optimum parameters of RP laser and magnetic field, noteworthy augmentation in the electron acceleration up to GeV range is obtained. The electron energy gain variations are plotted and analyzed for initial laser intensity, initial phase, electron initial energy and applied magnetic field parameters.

Electron acceleration by higher-order cosh-gaussian laser pulses in vacuum

Higher-order Cosh-Gaussian (ch-G) laser pulse is proposed for effective electron acceleration and energy gain in vacuum. The intensity distribution of ch-G laser is influenced by its higher-order (m) and decentered parameter (b) controlled propagation features. The laser pulse order m= (0,1,2,3) classifies them as Gaussian, ch-G, ch-square-G, and ch-cube-G laser pulses. The flatter the beam profile becomes as the order (m) increases, with the loss of its initial maximum intensity center at a slower rate as m increases, making it suitable for long-distance propagation. The increase in decentered parameter b, changes its properties from Gaussian(b=0) to flat top (b>1) and ring-shaped (b∼2) forms. As a result, it operates well enough to quickly accelerate electrons to exceedingly high energies in a short period of time. The analytic results show that altering the m and b combination leads to a significant rise in electron energy with laser intensity (∼1020W/cm2) of the order of GeV in vacuum.

Effect of carburized time on microstructure and properties of W[sbnd]Cu composites fabricated by vacuum pulse carburization

In this study, gradient WCX ceramic particle-reinforced WCu composites were successfully fabricated by vacuum pulse carburization and an infiltration sintering process. The effects of carburization time on the microstructure, hardness, compressive strength, wear resistance, and electrical conductivity were investigated in detail. With an increase in carburization time, the edges of the W particles became coarse until a large number of cracked structures appeared. The WC phase and a small amount of the W2C phase were the primary carbides generated upon carburization for 60 to 100 min. The WCX gradient microstructure significantly improved the mechanical properties of the WCu composites. The gradient structure also ensured the electrical conductivity of the WCu composites.

Effects of the Marinating Process on the Quality Characteristics and Bacterial Community of Leisure Dried Tofu

Leisure dried tofu (LD-tofu) was prepared using two different marinating processes: the repeated heating method (RHM) and the vacuum pulse method (VPM). The quality characteristics and bacterial community succession of LD-tofu and the marinade were evaluated. The results showed that the nutrients in LD-tofu were easily dissolved into the marinade during the marinating process, while the protein and moisture content of RHM LD-tofu changed most dramatically. With the increase in marinade recycling times, the springiness, chewiness and hardness of VPM LD-tofu increased significantly. The total viable count (TVC) of the VPM LD-tofu decreased from the initial value of 4.41 lg cfu/g to 2.51-2.67 lg cfu/g as a result of the marinating process, which had a significant inhibitory effect. Additionally, 26, 167 and 356 communities in the LD-tofu and marinade were detected at the phylum, family and genus levels, respectively. Pearson correlation analysis showed that Pseudomonadaceae, Thermaceae and Lactobacillaceae were closely related to the quality characteristics of LD-tofu, whereas Caulobacteriaceae, Bacillaceae and Enterobacteriae were closely related to the marinade. The present work provides a theoretical basis for the screening of functional strains and quality control in LD-tofu and marinade.

РАЗРАБОТКА ТЕХНОЛОГИИ ПРОИЗВОДСТВА ХМЕЛЕВО-ТОПИНАБУРНОЙ ЗАКВАСКИ

Enrichment of bread with nutrients useful for the human body contributes to the improvement of the population, so it is necessary to make a careful choice of ingredients. The article discusses the possibility of preparing a spontaneous fermentation starter based on an aqueous extract of hop cones and Jerusalem artichoke roots. Data on the content of vitamins, macro- and microelements in Jerusalem artichoke are given. A technological block diagram for the preparation of hops Jerusalem artichoke sourdough has been developed, including water extraction of hop cones. When comparing three methods of extraction, it was found that the most effective is vacuum extraction at a temperature of 54- 56ºС on the developed universal extract-evaporator plant. To increase the shelf life of the starter (up to 6 months), it is proposed to use a two-stage convective vacuum pulse drying. A description is given of the technology for drying hop Jerusalem artichoke starter culture under gentle conditions (heat carrier temperature not more than 46°C, speed 2.5 m/s) with maximum preservation of biologically active substances contained in the prepared mixture. The initial moisture content of the raw material was 61%, drying at the first stage was carried out to a critical moisture content of 25%. After the second stage, a final moisture content of 5% was obtained. The positive effect of vegetable raw materials on the quality of the starter has been proven experimentally. Thus, the lifting power of baking sourdough with the addition of Jerusalem artichoke is higher compared to a similar sourdough without the use of this root crop. The lifting force was compared using the “ball” method (the difference in ascent time was on average 5-10 minutes). In addition, the prototypes had better pulp porosity compared to traditional products, and also surpassed them in taste and aroma.

Proton acceleration in vacuum using frequency-chirped laser pulses

Recent investigations demonstrate the achievement of protons with energies of several hundred MeV via vacuum laser acceleration mechanisms. However, the symmetric electric field from an unchirped laser pulse is not efficient in generating a high energy proton beam. It is known that a proton can gain energy from a chirped laser pulse through the optimal phase synchronization between the proton and the laser field. In this study, we investigate the proton acceleration by different frequency-chirped laser pulses in vacuum both analytically and numerically. We consider four different situations constituting the unchirped, linear, quadratic, and sinusoidal chirped laser pulses. For the unchirped laser case, the pulse symmetry results in no net energy gain for the proton from the laser field. Conversely, using frequency-chirped laser pulses renders high energy to the proton compared with the unchirped laser pulse. We compared three different chirped cases, and found that a sinusoidal chirped laser pulse renders maximum acceleration to the protons compared to the linear and quadratic chirped situations. There exists an optimal chirp parameter for each type of chirped laser pulse.

Comprehensive analysis of vacuum application in desalting lean white fish to develop a highly acceptable ready-to-use product

Changes in consumers' lifestyle, coupled with a trend towards healthier low-sodium food, have led to a decline in salted fish consumption. Today, ready-to-use, high-quality food products are what the consumer demands. We evaluated the use of vacuum during the desalting of heavily salted hake, to develop a ready-to-use product. A partial vacuum pressure of 10,000 Pa was applied for 15 min (DV), and for 5 min followed by 5 min at atmospheric pressure in three pulses (DVP). Both were compared with the treatment at atmospheric pressure (DC). The application of vacuum during desalting hake fillets had significant effects on product yield and salt transfer kinetics. DV was more effective when considering the product yield, while DVP samples reached the lowest NaCl values. Vacuum pulses reduced the desalting time by at least 66%, resulting in lower aw values that would influence the product's microbiological stability. Vacuum did not modify the product texture significantly, though the effect of DVP was greater compared to DC. The developed desalted product had high sensory acceptability scores when evaluated by the consumer panel. The use of vacuum pulses would be a feasible and economical alternative to reduce desalting processing times of this ready-to-use fish product.

The impact of using vacuum and isomaltulose as an osmotic agent on mass exchange during osmotic dehydration and their effects on qualitative parameters of strawberries

AbstractThe impregnation of isomaltulose is an interesting strategy for the enrichment of strawberries since it is a carbohydrate with low glycemic and cariogenic indexes. The osmotic enrichment of strawberries with isomaltulose was performed considering the vacuum pulse in the first 0, 10, and 20 min in a total process time of 300 min, at 25°C. The tested solution concentrations were 25% and 35% (w w−1) of isomaltulose. The kinetics of solid gain, water loss, moisture content, and weight reduction were obtained. The fresh and final products had some physical and nutritional parameters evaluated. Osmotic processes resulted in a reduction of moisture content, water activity (aw), acidity, total anthocyanins and phenolic contents and antioxidant capacity, increased pH, influenced colorimetric parameters and caused shrinkage of the samples. The higher impregnation of isomaltulose was obtained with the vacuum pulse, which was 82% higher than the osmotic process without the vacuum pulse. The atmospheric process resulted in higher bioactive compounds levels and lower shrinkage and lower total color difference. Therefore, the 35% solution and use of vacuum were recommended when the objective was to maximize mass exchanges, while the 25% solution and without vacuum pulse were indicated for higher retention of strawberry bioactive compounds. The time of vacuum application at the beginning of the osmotic dehydration process and the use of osmotic solutions of different concentrations can result in different rates of dehydration and impregnation of isomaltulose in the strawberry and can influence important qualitative parameters. The evaluation of these factors helps in the optimization of the production of osmo‐dehydrated strawberries, increasing the process efficiency and the preservation of product quality.Practical ApplicationsThe time of vacuum application at the beginning of the osmotic dehydration process and the use of osmotic solutions of different concentrations can result in different rates of dehydration and impregnation of isomaltulose in the strawberry and can influence important qualitative parameters. The evaluation of these factors helps in the optimization of the production of osmo‐dehydrated strawberries, increasing the process efficiency and the preservation of product quality.

Acceleration of electrons by tightly focused azimuthally polarized ultrashort pulses in a vacuum.

Using the complex sink-source model (CSSM) and the Hertz potential method (HPM), the electromagnetic field expressions of tightly focused ultrashort azimuthally polarized pulses can be obtained. By numerically solving the relativistic Newton-Lorentz equation, the acceleration and confinement of electrons by the sub-cycle and few-cycle azimuthally polarized ultrashort pulses in vacuum are studied. Considering the radiation reaction force, it is found that electrons with an initial kinetic energy of less than 1MeV can be accelerated to hundreds of MeV and can be confined in the range of less than 1 micron for hundreds of femtoseconds in the direction perpendicular to the pulse propagation (transverse direction) by the pulses. With the increase of the beam waist and the intensity of the pulse, the electrons can obtain the exit kinetic energy exceeding 1GeV. When electrons are accelerated by the few-cycle pulses, the confined time of the electrons in the transverse direction is three times longer than that of the sub-cycle pulse. When the initial velocity of the electron points to a point in front of the focus, the electron can obtain the maximum exit kinetic energy. The change of the angular frequency corresponding to the spectral peak of the electromagnetic radiation from the electron acceleration with the electric field amplitude parameter E0 of the pulse is studied. The phenomena of redshift and blueshift of the spectrum peak frequency of the electron radiation with the E0 are found. These studies provide the methods to confine the movement of electrons in certain directions and accelerate electrons in the same time.

Influence of process conditions on the mass transfer of osmotically dehydrated jambolan fruits

Jambolan (Syzygium cumini) is a tropical fruit rich in anthocyanin pigments, but its fragile skin and pulp present low protection against physical damages and microorganisms. In this sense, a preservative technology, as osmotic dehydration (OD), was studied to investigate the impact of some variables over this process. At first, fruits of jambolan were submitted to physical and physical-chemical analysis. Furthermore, whole fruits underwent OD following a fractional factorial design. The influence of the process variables: temperature (20-50ºC), sucrose concentration (30-60%), pressure (10-90 kPa), vacuum pulse time (5-15 min), calcium lactate concentration (0-4%) and number of vacuum pulse (1-3) was assessed on water loss (WL), solid gain (SG) and weight reduction (WR). In general, biometric analysis showed positive and significant correlation among the physical characteristics of jambolan. Physical-chemical assay demonstrated that the fresh fruit presents a potential source of bioactive compounds. The screening design showed that temperature, sucrose concentration, calcium lactate concentration and pressure affected the WL in jambolan. On the other hand, vacuum pulse time and number of vacuum pulse showed no influence on the WL, SG and WR; therefore, these variables must be fixed at the most economically viable level for any further trials.

Characterization of vacuum and deep ultraviolet pulses via two-photon autocorrelation signals.

Characterization of ultrashort vacuum and deep ultraviolet pulses is important in view of applications of those pulses for spectroscopic and dynamical imaging of atoms, molecules, and materials. We present an extension of the autocorrelation technique, applied for measurement of the pulse duration via a single Gaussian function. Analytic solutions for two-photon ionization of atoms by Gaussian pulses are used along with an expansion of the pulse to be characterized using multiple Gaussians at multi-color central frequencies. This approach allows one to use two-photon autocorrelation signals to characterize isolated ultrashort pulses and pulse trains, i.e., the time-dependent amplitude and phase variation of the electric field. The potential of the method is demonstrated using vacuum and deep ultraviolet pulses and pulse trains obtained from numerical simulations of macroscopic high harmonic spectra.

Conductive drying methods for producing high-quality restructured pineapple-starch snacks

Restructured fruit pulps can be dried to obtain new added-value products. In the present study, restructured pineapple pulp was dehydrated by two innovative methods, cast-tape drying (CTD) and conductive multiflash drying (KMFD). The snack produced was evaluated by physical, chemical, and sensory aspects. CTD required a half time length (30 min) than KMFD (60 min) for drying. The drying processes did not affect the ascorbic acid content present in the fresh fruit but decreased its antioxidant activity in 50–70%. The natural volatile compounds were also changed. The product from KMFD was preferred by consumers, which may be a consequence of a more expanded structure with larger pores created by the vacuum pulse and flash water evaporation. KMFD resulted in more jagged acoustic-mechanical curves, which is a characteristic of crispy foods. Therefore, KMFD can be considered the most promising process to produce restructured pineapple snacks in approximately one hour with excellent quality. Industrial relevanceIn recent years, a growing number of consumers have been looking for healthy, convenient, and ready-to-eat foods. Dried restructured fruits can be healthy snacks with very attractive sensory characteristics depending on the drying method. Cast-tape drying (CTD) and conductive multiflash drying (KMFD) are novel technologies with great potential to produce high-quality dried products at an industrial scale in a relatively short time. This study provides important results regarding the most suitable drying processes setup for producing high-quality dried restructured pineapple.

МАТЕМАТИЧЕСКОЕ МОДЕЛИРОВАНИЕ ЭНЕРГЕТИЧЕСКИХ СПЕКТРОВ, ФОРМИРУЮЩИХСЯ ПРИ УСКОРЕНИИ ЭЛЕКТРОНОВ РЕЛЯТИВИСТСКИ ИНТЕНСИВНЫМИ ГАУССОВСКИМИ И ЛАГЕРРОВСКИМИ ЛАЗЕРНЫМИ ИМПУЛЬСАМИ

A mathematical model is constructed that describes the propagation of laser pulses in vacuum, taking into account the corrections due to their finite duration. On its basis, using Newton relativistic equations with the corresponding Lorentz force, the energy spectra of an ensemble of electrons are simulated by relativistically intense laser radiation. The characteristics of these spectra are studied for the cases of Gaussian and Laguerre optical pulses. Electronic spectra in the fixed angular ranges are localized around the relativistic maxima in the case of Gaussian pulses, but are substantially non-monoenergetic in the case of Laguerre pulses.