Non-thermal Method Research Articles

Characterization of continuous-flow pulsed UV light reactors for processing of liquid foods in annular tube and coiled tube configurations using actinometry and computational fluid dynamics

Pulsed UV light (PL) processing is a growing non-thermal method of treatment of solid and liquid foods. Proper design of liquid food treatment requires understanding of hydrodynamics, and PL dose distribution within the reactor. In this study, three-dimensional light energy distribution around a PL lamp was modeled based on three-parameter Gaussian model in air, model liquid foods and skim milk. Two different types of reactors, annular tube and coiled tube, are characterized based on hydrodynamics, potassium iodide-iodate based actinometry and computational fluid dynamics. Hydrodynamics result revealed a better performance of coiled tube reactor having narrower residence time distribution, secondary flow vortices and more turbulence which induce radial mixing, as opposed to axial mixing in annular tube reactor. Actinometry results showed higher PL dose (36.36–1148.63 J L−1) was absorbed in the coiled tube geometry than annular geometry (22.22–322.22 J L−1). Numerical simulations also showed a higher process uniformity in the coiled tube PL reactor.

Production of Low-fat mayonnaise without preservatives: Using the ultrasonic process and investigating of microbial and physicochemical properties of the resultant product.

In this study, ultrasonication was used at 20 kHz, 750 W for 5 min, as a nonthermal alternative to pasteurization and as a substitute for benzoate‐sorbate preservatives. Also, its efficiency on microbial and physicochemical properties of low‐fat mayonnaise stored at 4°C was investigated. The results showed the reduction of total counts of micro‐organisms, acid‐tolerant bacteria, molds, and yeasts during six months shelf life compared with the control samples. Sonicated mayonnaise samples had lower pH values and higher acidity in comparison with control samples during the storage. The speculation was verified through the microstructure of mayonnaise samples during storage time observed by SEM micrographs. The overall results indicated that it was possible to produce sodium benzoate and potassium sorbate‐free mayonnaise using the ultrasonic nonthermal method.

Cold plasma enzyme inactivation on dielectric properties and freshness quality in bananas

Cold plasma (CP) technology is a novel, non-thermal method to inactive enzymes and improve the quality of food materials. In this study, banana samples were processed via CP treatment for different lengths of time (1, 1.5, and 2 min intervals) and their properties, including dielectric properties, enzyme activities, levels of ROS (reactive oxygen species), enzymatic browning products, color, flavor compounds, and surface microstructure, were measured. The dielectric constant (ε′) and loss factor (ε′′) after CP treatment decreased with increasing frequency and increased with increasing temperature, respectively. Higher values of ε′ and ε′′ could also be found after CP treatment. The enzyme activity of polyphenoloxidase (PPO) and peroxydase (POD) decreased with increasing CP treatment time. ROS levels in cells increased after CP treatment, and quinones generated from enzymatic browning decreased at extended treatment times. CP treatment had a positive effect on the surface color of bananas due to enzyme inactivation, while significant differences in a⁎ and b⁎ values at different treatment times were noted. However, surface morphology changed with increasing CP processing time, leading to a rougher surface microstructure. CP treatment has little impact on flavor compounds and has demonstrated a potential pretreatment technology for dielectric heating/drying.

Effect of dielectric barrier discharge cold plasma treatments on flavor fingerprints of brown rice

A non-thermal processing method was developed to promote preservation of brown rice using dielectric barrier discharge cold plasma (DBD-CP). Physicochemical properties including free fatty acid (FFA) content, surface color change, volatile organic components (VOCs) and flavor fingerprints were evaluated in brown rice submitted to DBD-CP. FFA levels were 25.2% lower in treated samples compared to the control, and a more stable surface color was obtained at the end of the storage period. A total of 35 major VOCs could be detected in treated samples, and reduced levels of hexanal can be used as an indicator of DBD-CP treatment in brown rice during storage. Moreover, the flavor fingerprints in DBD-CP treated groups can be successfully distinguished through headspace gas chromatography ion mobility spectrometry. Collectively, application of DBD-CP treatment could be utilized as a feasible approach to promote stabilization of brown rice and preserve flavor during storage.

Inactivation of Foodborne Viruses by High-Pressure Processing (HPP).

High-pressure processing (HPP) is an innovative non-thermal food preservation method. HPP can inactivate microorganisms, including viruses, with minimal influence on the physicochemical and sensory properties of foods. The most significant foodborne viruses are human norovirus (HuNoV), hepatitis A virus (HAV), human rotavirus (HRV), hepatitis E virus (HEV), human astrovirus (HAstV), human adenovirus (HuAdV), Aichi virus (AiV), sapovirus (SaV), and enterovirus (EV), which have also been implicated in foodborne outbreaks in various countries. The HPP inactivation of foodborne viruses in foods depends on high-pressure processing parameters (pressure, temperature, and duration time) or non-processing parameters such as virus type, food matrix, water activity (aw), and the pH of foods. HPP was found to be effective for the inactivation of foodborne viruses such as HuNoV, HAV, HAstV, and HuAdV in foods. HPP treatments have been found to be effective at eliminating foodborne viruses in high-risk foods such as shellfish and vegetables. The present work reviews the published data on the effect of HPP processing on foodborne viruses in laboratory media and foods.

The possibility of increasing the shelf life of dried apricot with application of uv radiation

The use of physical methods of processing, in particular ultraviolet radiation, is used in the food industry for the purpose of disinfection of raw materials, semi-finished products and finished products, which increases the storage time. The process of processing food products with ultraviolet light quickly proved itself. This method does not change the taste of the product, increases the shelf life and sales, and is a non-thermal method of deactivating pathogens. The wide use of the bactericidal effect of UV rays for food products is limited by their low penetration capacity, so the UV spectrum can be used mainly for sur-face sterilization, provided that the deep layers of the material do not contain microflora. The effectiveness of UV radiation depends on the following factors: the source and the UV dose; the sensitivity of microorganisms to UV light; the composition and physical properties of the product. Object of research: model media containing native microflora of dried fruit raw materials "dried Apri-cots". The research was carried out using model media simulating the proper-ties of the raw material surface, excluding its protective mechanisms and allow-ing to reveal the true dynamics of inhibition of native microflora. Native micro-flora of dried fruits implies a set of microorganisms. Literature sources have shown the possibility of the presence of such types of microorganisms as E. coli, Salmonella, Candida, Pseudomonas, spore forms of microorganisms on the surface of raw materials. During the experiment it was determined that the treatment duration of 5 min reduced the initial contamination of 2 order pro-cessing in 10 minutes – 2.6 the order in 15 minutes – 2.7 order and 20 minutes for 3 orders of magnitude.

Systematic Analysis Reveals Thermal Separations Are Not Necessarily Most Energy Intensive

Summary At the industrial level, separation of a variety of mixtures is predominantly carried out by thermally driven processes such as distillation. Nevertheless, the current literature seems to suggest that much is to be gained by replacing these processes with alternative non-thermal methods, which will potentially require a fraction of the energy used by distillation. This is primarily due to the widespread perception that thermal separation processes, particularly those that involve vaporization, are highly energy intensive. However, this belief is not well founded, because it is based on extrapolation from comparisons in the literature, many of which make ad-hoc assumptions and result in incorrect conclusions. Our analysis shows that this confusion arises because the processes utilize different types of energy: heat and electricity. Here, we present a consistent framework that enables a fair comparison between different processes that consume different forms of energies. Using this framework, we refute the general perception that thermal separation processes are inherently the most energy intensive and conclusively show through the examples of two challenging mixtures constituting components with low relative volatilities, that distillation processes, when run properly, can consume remarkably lower fuel than non-thermal membrane alternatives, which have often been touted as more energy efficient.

Предобработка нитевидной микроплазмой при поддержке термоэлектронной эмиссии в процессе сублимационной сушки плодов манго

Introduction. The research objective was to study the effect of filamentous microplasma pretreatment on the efficiency of freeze drying. It featured mango fruit and assessed the quality of the dried product. Year-round availability of exotic fruit poses a challenge of providing consumers with high-quality food products. Freeze-drying, if combined with advanced electrophysical technologies, makes it possible to maintain the high quality of the product while improving the processing. This non-thermal method technology presupposes pretreatment with filamentous microplasma (FM) and thermoelectric emission. FM affects the membrane of plant cells and forms a through channel, thus improving mass transfer. Study objects and methods. Before freeze-drying, fresh mango fruit was cut into slices of 6.0 ± 0.5 mm each and the average diameter of 72 ± 3 mm. Freeze-dried fruits were analyzed according to the degree of rehydration and quality. FM treatment was performed at the electric field strength E = 600 kV/m, while the specific energy was 1 kJ/kg per unit. Results and discussion. FM pretreatment with thermoelectric emission reduced the drying time by 38%, which was enough to achieve equilibrium moisture content. It also increased the degree of rehydration from 2.58 to 3.14. FM pretreatment raised the total content of phenols and carotenoids, but reduced the total content of flavonoids. FM pretreatment also affected the antioxidant capacity, reducing it from 0.43 to 0.41 by the ABTS method and from 0.90 to 0.75 by the DPPH method. Conclusion. FM pretreatment increased the ability to restore the freeze-dried samples. The mango samples preserved the high content of phenols and carotenoids. The antioxidant capacity of the FM-treated samples proved to be slightly lower than in the control samples. In general, pretreatment with filamentous microplasma and thermoelectric emission had a positive effect on the quality of freeze-dried mango, reduced the processing time, and improved the rehydration characteristics of the final product.

Continuous-flow UV-C processing of kale juice for the inactivation of E. coli and assessment of quality parameters

Ultraviolet-C (UV-C) light is a non-thermal method for improving the safety and shelf-life of cold-pressed juices with minimal impact on quality and nutrition. Most previous studies have investigated fruit juices as opposed to particulate dense leafy green juices with very low UV transmittance (UVT). Pure kale juice is a common juice ingredient and represents the worst-case scenario in terms of low UVT green juices. This study validated the use of continuous benchtop UV-C treatment at 253.7 nm for 5-log reduction of non-pathogenic Escherichia coli P36 in kale juice. An average absorbed fluence of 108.3 mJ cm−2 resulted in a 5.8 log reduction of E. coli P36. At a fluence comparable to that reported for commercial juice processing (74.0 mJ cm−2), kale juice exhibited a decrease in absorption coefficient, while sedimentation, supernatant browning and pectin methylesterase activity increased with no effect on the chlorophyll content, colour, viscosity or antioxidant content.

Optimization of UV-C Processing of Donkey Milk: An Alternative to Pasteurization?

Simple SummaryDonkey milk has received much interest lately due to its chemical composition, which is very close to human milk as well as to its unique functional properties (antibacterial, antioxidant, immunomodulatory, and antitumor activities). Furthermore, donkey milk is considered a valid alternative milk for infants and adults suffering from cow milk protein allergy. However, it is recommended by pediatricians and clinicians that raw donkey milk must be thermally processed to render it safe for sensitive population (i.e., infants and immunocompromised). On the other hand, thermal processing is known to reduce the bioactivity of milk. Consequently, the objective of this study is to determine the feasibility of the UV-C system to inactivate or reduce foodborne pathogens in raw donkey milk in order to produce a safe, non-thermally processed donkey milk that can be consumed by special population groups (infants, elderly, immunocompromised). Results obtained from this study indicate that UV-C has the potential to be used as a non-thermal treatment to reduce food borne pathogens present in raw donkey milk.The effect of UV-C light technology on the inactivation of six foodborne pathogens inoculated in raw donkey milk was evaluated. Fresh raw donkey milk was artificially inoculated with the following foodborne pathogens—L. inoccua (NCTC 11288), S. aureus (NCTC 6571), B. cereus (NCTC 7464), Cronobacter sakazakii (NCTC 11467), E. coli (NCTC 9001), Salmonella enteritidis (NCTC 6676)—and then treated with UV-C doses of up to 1300 J/L. L. innocua was the most UV-C-resistant of the bacteria tested, requiring 1100 J/L for complete inactivation, while the rest of the bacteria tested was destructed in the range of 200–600 J/L. Results obtained from this study indicate that UV-C light technology has the potential to be used as a non-thermal processing method for the reduction of spoilage bacteria and foodborne pathogens that can be present in raw donkey milk.

Possibility to extend the shelf life of NFC tomato juice using cold atmospheric pressure plasma

Cold Atmospheric pressure Plasma (CAP) is a non-thermal method used in food processing. CAP generated with the use of nitrogen in a Glide-arc device for 300 to 600 s exhibited high potential for microbial decontamination and did not induce substantial changes in the physicochemical properties of NFC tomato juice. Samples exposed to cold atmospheric plasma had mostly an intact structure, as revealed by digital microscopy. The investigations indicate that CAP can be applied for biological and chemical waste-free decontamination of food and extension of its shelf life.

Introducing pulsed electric field treatments for fruit juices industry in Egypt as an alternative of thermal pasteurization

The aim of this study was to investigate the efficiency test of a laboratory scale of pulsed electric field (PEF) device, on strawberry juices treated in a batch system. strength was (18.5 kV/cm for 500 µs at 100 Hz) for 60 sec. or 90 seconds as alternative physical and non-thermal method compared with those of thermal traditional method of pasteurization used Indirect heating by double jacket suit at (90оC / 5 min) and unprocessed juice (Fresh juice) as a reference (Control) was studied in terms of effect of these treatments’ physico-chemical characteristics, (TSS, pH, acidity and color), ascorbic acid, microbial stability and shelf life, of treated strawberry juices. After treatments and whether storage at room temperature at (22°C ±3) for 45 days or in refrigerator at (4°C ±1) for 105 days. Pulsed electric field device subject of study was effective as thermal pasteurization not only to achieve microbial stability juices, but also to obtain juices with a high content of vitamin C like fresh, perfectly.

In Vitro Study of Calcium Microsecond Electroporation of Prostate Adenocarcinoma Cells.

Electroporation, applied as a non-thermal ablation method has proven to be effective for focal prostate treatment. In this study, we performed pre-clinical research, which aims at exploring the specific impact of this so-called calcium electroporation on prostate cancer. First, in an in-vitro study of DU 145 cell lines, microsecond electroporation (μsEP) parameters were optimized. We determined hence the voltage that provides both high permeability and viability of these prostate cancer cells. Subsequently, we compared the effect of μsEP on cells’ viability with and without calcium administration. For high-voltage pulses, the cell death’s mechanism was evaluated using flow-cytometry and confocal laser microscopy. For lower-voltage pulses, the influence of electroporation on prostate cancer cell mobility was studied using scratch assays. Additionally, we applied calcium-binding fluorescence dye (Fluo-8) to observe the calcium uptake dynamic with the fluorescence microscopy. Moreover, the molecular dynamics simulation visualized the process of calcium ions inflow during μsEP. According to our results calcium electroporation significantly decreases the cells viability by promoting apoptosis. Furthermore, our data shows that the application of pulsed electric fields disassembles the actin cytoskeleton and influences the prostate cancer cells’ mobility.

SiO2 Is Wasted Space in Single-Nanometer-Scale Silicon Nanoparticle-Based Composite Anodes for Li-Ion Electrochemical Energy Storage

The electrode processing conditions of silicon-based composite anodes play a pivotal role in the resulting interfacial chemical speciation and, thus, the electrochemical cycling behavior of the electrode. Systematically investigating how small chemical changes to the surface of the silicon nanoparticle (NP) affect larger, electrode-level properties is a strategy that will inform design principles to maximize electrode energy density and extend electrode lifetime. Here, we incorporate silicon nanoparticles (NPs) with an average diameter of 5.5 nm synthesized from the gas phase through a nonthermal plasma method into composite anode half-cell coin cells. We perform chemistry to functionalize the native hydride-terminated silicon NP surface with N-methylpyrrolidone (NMP) to improve slurry properties and reduce the silicon reactivity prior to composite electrode fabrication. We construct composite electrodes from these silicon NPs and observe an 86% capacity retention over 100 cycles at a rate of C/5, with an initial silicon specific capacity of 2600 mAh/g. We expose the same Si NPs to water that completely oxidizes these small-diameter NPs to SiO2 and find that the SiO2 NPs in the same electrode configuration exhibit no obvious lithium alloying capacity in the electrochemical potential range of lithium silicide alloy formation. As this result stands in contrast to existing literature, we provide a discussion on the origin of the discrepancies.

The role of radiolysis in the modelling of C2H4O2 isomers and dimethyl ether in cold dark clouds

ABSTRACT Complex organic molecules (COMs) have been detected in a variety of interstellar sources. The abundances of these COMs in warming sources can be explained by syntheses linked to increasing temperatures and densities, allowing quasi-thermal chemical reactions to occur rapidly enough to produce observable amounts of COMs, both in the gas phase, and upon dust grain ice mantles. The COMs produced on grains then become gaseous as the temperature increases sufficiently to allow their thermal desorption. The recent observation of gaseous COMs in cold sources has not been fully explained by these gas-phase and dust grain production routes. Radiolysis chemistry is a possible non-thermal method of producing COMs in cold dark clouds. This new method greatly increases the modelled abundance of selected COMs upon the ice surface and within the ice mantle due to excitation and ionization events from cosmic ray bombardment. We examine the effect of radiolysis on three C2H4O2 isomers – methyl formate (HCOOCH3), glycolaldehyde (HCOCH2OH), and acetic acid (CH3COOH) – and a chemically similar molecule, dimethyl ether (CH3OCH3), in cold dark clouds. We then compare our modelled gaseous abundances with observed abundances in TMC-1, L1689B, and B1-b.

In vivo analysis of the origin and characteristics of gaseous microemboli during catheter-mediated irreversible electroporation.

Aims Irreversible electroporation (IRE) ablation is a non-thermal ablation method based on the application of direct current between a multi-electrode catheter and skin electrode. The delivery of current through blood leads to electrolysis. Some studies suggest that gaseous (micro)emboli might be associated with myocardial damage and/or (a)symptomatic cerebral ischaemic events. The aim of this study was to compare the amount of gas generated during IRE ablation and during radiofrequency (RF) ablation.Methods and resultsIn six 60–75 kg pigs, an extracorporeal femoral shunt was outfitted with a bubble-counter to detect the size and total volume of gas bubbles. Anodal and cathodal 200 J IRE applications were delivered in the left atrium (LA) using a 14-electrode circular catheter. The 30 and 60 s 40 W RF point-by-point ablations were performed. Using transoesophageal echocardiography (TOE), gas formation was visualized. Average gas volumes were 0.6 ± 0.6 and 56.9 ± 19.1 μL (P < 0.01) for each anodal and cathodal IRE application, respectively. Also, qualitative TOE imaging showed significantly less LA bubble contrast with anodal than with cathodal applications. Radiofrequency ablations produced 1.7 ± 2.9 and 6.7 ± 7.4 μL of gas, for 30 and 60 s ablation time, respectively.Conclusion Anodal IRE applications result in significantly less gas formation than both cathodal IRE applications and RF applications. This finding is supported by TOE observations.

Quality parameters and bioactive compound bioaccessibility changes in probiotics fermented mango juice using ultraviolet-assisted ultrasonic pre-treatment during cold storage

Ultrasound can be applied in fruit juice fermentation as an innovative non-thermal sterilisation method with product quality-promoting potential. In this study, the qualities changes in fermented mango juice (UFJ) pre-treated by ultraviolet-assisted ultrasound (US-UV) during the 30-days of cold storage (4 °C) were evaluated. The essential qualities of UFJ were enhanced compared with the fresh juice and traditional fermented juice (thermal pre-treatment). Additionally, UFJ showed better performances concerning physical features (suspension stability, particle size, viscosity, and colour), pH and acidity, as well as bioactive compounds stability (soluble dietary fibre, carotenoids, total phenols, and ascorbic acid) than fresh juice during storage, revealing that the higher qualities of fermented mango juice were improved by US-UV pre-treatment. More importantly, the in vitro simulated gastrointestinal digestion validated that the bioactive compounds in UFJ had better stability and bioaccessibility than fresh juice during various storage periods, and lead to better antioxidant performance. As an effective and novel non-thermal technology, US-UV pretreatment can be considered a promising alternative method to thermal sterilisation in the juice industry.

Understanding the role of atmospheric cold plasma (ACP) in maintaining the quality of hairtail (Trichiurus Lepturus)

Impacts of atmospheric cold plasma (ACP) on the properties of muscle protein and performance of extracted crude enzyme of hairtail (Trichiurus Lepturus) fish have been evaluated. A decrease in extracted crude enzyme activity with increasing the ACP treatment time has been found, and the highest reduction (p < 0.05) value of 0.035 units/mg proteins was obtained after 240 s. A considerable increase in the carbonyl content in the treated sample for about three times higher than the control sample was found, and a decrease of total sulfhydryl content to 0.34 nmol/mg protein. Texture profile analysis, water holding capacity, and the color properties of the muscle protein improved significantly in the samples treated with ACP. SDS-PAGE pattern showed an increase in the band intensity of cross-linked myosin heavy chains and actin proteins. Based on these outcomes, ACP could play a significant role as a promising non-thermal method to prolong the shelf-life of hairtail fish.

A rapid and non-destructive detection of Escherichia coli on the surface of fresh-cut potato slices and application using hyperspectral imaging

Abstract The contamination of foodborne Escherichia coli in fresh-cut products has become a major problem of public health around the world, so that early and rapid detection of contamination is crucial. This study explored the potential of hyperspectral imaging (HSI) measurement of contamination on the surface of fresh-cut potato slices in visible-near infrared (Vis-NIR, 400-1000 nm) region. Four preprocessing methods and the genetic algorithm (GA) were explored to handle spectral data and select characteristic wavelengths so as to establish linear and non-linear regression models. The performance of the back-propagation neural network (BP-NN) model based on full-spectrum was satisfactory, with an overall accuracy of 97.6 % and residual predictive deviation (RPD) of 6.7. Based on the BP-NN model, the research successfully explored the optimum treatment time (20 min) of a non-thermal and environmental-friendly method to inactivate the E. coli on the surface of fresh-cut potato slices, thus confirming the potential application of HSI for the first time. The overall results showed that HSI could provide a rapid and non-destructive approach for the detection of foodborne pathogens on the surface of fresh-cut products.

Ultra-trace level detection of nonvolatile compounds studied by ultrasonic cutter blade coupled with dielectric barrier discharge ionization-mass spectrometry

In analytical mass spectrometry, an efficient desorption is needed for nonvolatile compounds at ultra-trace level detection. In this paper, an ultrasonic cutter-assisted non-thermal desorption method for ultra-trace level detection of different types of nonvolatile compounds such as drugs of abuse, explosives, pharmaceuticals, spinosad, cholesterol, rhodamine B, glucose and amino acids has been described. The relevant compounds were deposited on the ultrasonic blade except pharmaceutical tablets that were used directly, and gently touched on perfluoroalkoxy (PFA) made substrate with oscillation frequency about 40 kHz in order to desorb the solid molecules. The desorbed gaseous molecules were ionized using a home-made helium dielectric barrier discharge ionization (DBDI) source and then detected by an ion trap mass spectrometer. The synergistic effect caused by gaining the oscillation and frictional/mechanical energy enhanced desorption of the solid molecules into gaseous phase, thereby, resulting in detection at ultra-trace level. PFA made substrate showed better limits of detection (LODs) compared to that of wood made substrate. The LOD values for most of the target analytes were ranging from 20.00 ± 0.91 to 200.25 ± 9.04 pg with RSD values ≤ 5% except for pharmaceutical tablets where only depletion amounts were estimated. The LOD value of cocaine in urine was 39.88 ± 1.65 pg with RDS ≤4.56% showed to be a very promising analytical tool for analysis of drugs of abuse in biological samples under ambient conditions. Drugs of abuse, pharmaceuticals, spinosad, cholesterol, rhodamine B, glucose and amino acids were detected mostly as their protonated molecular ions while RDX and HMX were detected as their molecular cluster/adduct ions as [M + NO2]- and [M + NO3]-, and AN was detected as a cluster ion of HNO3 with NO3-, [HNO3 + NO3]-, without suffering from fragmentation. An effective mechanism of the enhanced sensitivity of the tribodesorption-DBDI-MS system in analyzing the nonvolatile compounds has been discussed.