Microwave Treatment Time Research Articles

Biochemistry of microwave controlled Heracleum sosnowskyi (Manden.) roots with an ecotoxicological aspect

Sosnowski hogweed is an invasive weed in eastern-middle Europe that is dangerous to human health and the environment. The efficacy of its control using chemical and mechanical methods is limited. Electromagnetic radiation (microwaves) could be an environmentally friendly alternative for controlling this species. This study aims to: (1) Determine the effect of varying microwave treatment (MWT) durations on the control of S. hogweed using a device emitting microwaves at 2.45 GHz, 32.8 kW/m2; (2) Evaluate the impact of MWT on soil by an ecotoxicological bioassays; (3) Analyze biochemical changes occurring in the roots during the process. A field study was performed to assess the efficacy of S. hogweed control using MWT in times from 2.5 to 15 min. The MWT-treated soil was collected immediately after treatment (AT) and tested using bioassays (Phytotoxkit, Ostracodtoxkit, and Microtox). Fourteen days AT, the MWT hogweed roots were dug out, air-dried, and analyzed for the content and composition of essential oil, sugars, and fatty acids. According to the ecotoxicological biotests, the MWT soils were classified as non-toxic or low-toxic. The regeneration of hogweed was observed only in non-treated plants (control). Hogweed MWT for 2.5–15 min did not regenerate up to 14 days AT. The average weight of roots in hogweed MWT for 15.0 min was ca. two times smaller than the control plants. Those roots contained significantly higher amounts of sugars and saturated fatty acids than the control. We did not find a correlation between S. hogweed root essential oil content and composition and MWT time. The main compounds of essential oil were p‑cymene and myristicin. No highly photosensitizing compounds were identified in the tested root oil. We conclude that MWT of S. hogweed could be an environmentally safe and prospective control method, but more studies are needed.

The influence of the synthesis route and microwave activation on the CuFe2O4 spinel mixed oxide catalysts activity in N2O decomposition

In this study a comprehensive analysis of the influence of synthesis route of CuFe2O4 spinel mixed oxides on their catalytic performance in the N2O decomposition was carried out. A co-precipitation technique allowed one to obtain the CuFe2O4 spinel with a higher specific surface area and pore volume compared to the synthesis with the application of organic additives. This resulted in better catalytic performance of the CuFe2O4 samples prepared by co-precipitation. The microwave activation step with the duration of 1 min during the co-precipitation synthesis led to the formation of the CuFe2O4 spinel with a higher content of oxygen vacancies per 1 m2 in comparison with the sample obtained without the microwave activation. This fact caused a significantly higher specific activity of the CuFe2O4 spinel synthesized with the application of 1 min microwave activation. The increase of the microwave treatment time led to the fast growth of the contents of the CuO and α-Fe2O3 phases, which are less active in the N2O decomposition, resulting in the activity drop.

Synthesis and characterization of hydroxy propyl methyl Cellulose/Copper nanobiocomposites for antibacterial and antioxidant smart materials

The synthesis of hydroxy propyl methyl cellulose (HPMC)/copper nanobiocomposites adopting a microwave treatment. In this study, HPMC and copper nitrate at various concentration were mixed and subjected to varying microwave treatment times (10, 20, 30, 40, 50 and 60 s). UV–Vis spectroscopy was employed to analyse the physicochemical characteristics of HPMC/copper nanobiocomposites, with a maximal absorbance at 380 nm, indicating the formation of copper nanoparticles within the HPMC matrix. The interaction between copper nanoparticles and HPMC was further confirmed through FT-IR analysis. The SEM analysis displayed microporous structures ranging from 5 to 14 µm in diameter, with an average pore size of 7.0 ± 2.0 nm. The compositional analysis was done with EDS mapping. TEM analysis revealed spherical shaped copper nanoparticles with an average particle size about 2.5 nm in HPMC matrix. Remarkably, these nanobiocomposites exhibited a broad-spectrum antibacterial activity, displaying minimal inhibitory concentrations against both Gram-negative and Gram-positive bacterium. Significantly, the assessment of antibacterial activity in HPMC/copper nanobiocomposites demonstrated their efficacy against both Escherichia coli and Staphylococcus aureus. In addition to the antioxidant property, the antibacterial properties holds significant implications for their potential applications of HPMC/ copper nanobiocomposites in the fields of food packaging and biomedicine.

Effect of Synthesis Conditions on CuO-NiO Nanocomposites Synthesized via Saponin-Green/Microwave Assisted-Hydrothermal Method

This work presents the synthesis of CuO-NiO nanocomposites under different synthesis conditions. Nanocomposites were synthesized by merging a green synthesis process with a microwave-assisted hydrothermal method. The synthesis conditions were as follows: concentration of the metal precursors (0.05, 0.1, and 0.2 M), pH (9, 10, and 11), synthesis temperature (150 °C, 200 °C, and 250 °C), microwave treatment time (15, 30, and 45 min), and extract concentration (20 and 40 mL of 1 g saponin/10 mL water, and 30 mL of 2 g saponin/10 mL water). The phases and crystallite sizes of the calcined nanocomposites were characterized using XRD and band gap via UV-Vis spectroscopy, and their morphologies were investigated using SEM and TEM. The XRD results confirmed the formation of a face-centered cubic phase for nickel oxide, while copper oxide has a monoclinic phase. The calculated crystallite size was in the range of 29–39 nm. The direct band gaps of the samples prepared in this work were in the range of 2.39–3.17 eV.

Effect of microwave treatment on the alkaline extraction of proteins and phenolics from perilla seed meal in varying pH conditions: An optimization study using multicomponent analysis

Perilla seed meal (PSM) is a by-product rich in proteins and bioactive compounds obtained by cold pressed oil extraction method. Microwave is an efficient nonconventional technology usually used to accelerate the recovery of the extracts. In this study, pH, microwave power and treatment time were optimized to maximize the recovery of targeted compounds using Box–Behnken design. The pH was found to be the most significant variable affecting the yield followed by microwave power and treatment time (based on F-value). Compared to conventional alkaline extraction, an increase in the yield of protein content by 10.58%, antioxidant activity by 7.48% and total phenolic content by 21.59% was recorded at the optimal values of pH (11.5) microwave power (160 W) and treatment time (30 s). Moreover, principle component analysis revealed opposite correlation between antioxidant activity and extraction of protein/phenolics suggesting the loss of bioactivity at the higher yield of extracts. Also, from the clustering analysis, the effect of microwave treatment found to be lower in more extreme alkaline conditions compared to lower pH values. Hence, lower alkaline conditions are suggested for the microwave treatment to develop better control system in the extraction industry.

Effects of microwave on the structural and emulsifying properties and interfacial properties of oxidized soybean protein aggregates.

This research explored microwave treatment impact on the structuro-functional aspects of oxidized soy protein aggregates (OSPI). Data showed that oxidative treatment promoted the formation of high molecular weight aggregates through hydrophobic interactions, thereby disrupting the structure of natural soy protein isolates (SPI). Microwave treatment for an appropriate time (≤30s) caused the molecular structure of OSPI to open up and reduction in molecular weight and disulfide bond content, while absolute zeta potential increased. These modifications increased emulsifying capacity of OSPI, as well as the interfacial adsorption of protein. Longer microwave treatment times (>30s) caused OSPI to exhibit a tendency to aggregate in TEM and CLSM images. It indicated the appropriate microwave electromagnetic field effect and microwave heating effect could coordinatively regulate soy protein functional properties by modifying their aggregation behavior. The results provided new ideas for reducing resource waste, and further expanding soy protein application in the food industry.

Insight into the effect of microwave treatment on fat loss, fatty acid composition and microstructure of pork subcutaneous back fat

In this study, the effects of different microwave treatment times (10, 20, 30, 40, 50, and 60 s) on fat loss, fatty acid profile, lipid transfers, and microstructure of pork subcutaneous back fat (PSBF) were investigated. Results showed that the fat loss of PSBF after microwave treatment for 60 s was significantly increased (53.31%). Microwave treatment increased the proportion of saturated fatty acids but reduced the relative content of monounsaturated and polyunsaturated fatty acids. Cryo-scanning electron microscopy, ordinary optical microscope and confocal laser scanning microscope analysis demonstrated that microwave treatment facilitated a large outflow of fat from the adipocytes, and the increasing and then decreasing changes in the size of individual adipocytes. Magnetic resonance imaging enabled the visualization of fat migration of PSBF. Overall, PSBF can be used as a biological model to evaluate the effect of microwave treatment on the change and migration mechanism of fat.

Juniper berry essential oils as natural resources of biological and pharmacological high-valuable molecules

Dried juniper berries (Juniperus communis L.) as a source of nutritionally valuable essential oil (EOs) were used for their isolation by conventional hydrodistillation (HD) and modern technique - microwave-assisted hydrodistillation (MWHD). The chemical composition, and biological and microbiological potential of the isolated EOs, prepared by using different microwave energy power and microwave treatment time, were investigated. The essential oil kinetic release curves were mathematically modeled. Results of the research indicate that MWHD was a more favorable technique for EO isolation with higher biological activity than HD, where lower power of microwave radiation was more suitable for realizing a higher antioxidant activity. However, there were no statistically significant differences in the composition of essential oils obtained by different distillation techniques. Reduction of the isolation time of MWHD contributes to obtaining EOs with a very pronounced ability to inhibit excessive enzyme activity, while the production of EOs with strong microbiological activity requires a long isolation time. The EO of juniper berries obtained by MWHD could be characterized as a powerful natural product for the creation and formulation of new, as well as improving the quality of already existing food, pharmaceutical, and cosmetic products.

Microwave assisted zirconium oxide based catalytic activation of persulfate for methyl orange dye degradation

In this investigation, zirconium oxide (ZrO2) based activation of persulfate (PS) under microwave (MW) irradiation for methyl orange (MO) dye degradation was studied. ZrO2 was synthesized using facile hydrothermal method and it was characterized via XRD, FTIR, SEM, and TGA techniques. Subsequently, MW/ZrO2/PS experiments were conducted to explore the effect of ZrO2 dosage (0–1.5 g/L), initial MO concentration (15–250 mg/L), MW reactor temperature (60–90 ℃), MW power (240–700 W), PS dosage (50–250 mg/L), and presence of NaCl (0–5000 mg/L) on MO removal at pH ~ 7. Under the optimal conditions (ZrO2 ~ 0.5 g/L, MO concentration ~ 25 mg/L, MW temperature ~ 90 ℃, MW power ~ 560 W, and PS dose~250 mg/L), 99 % of MO removal and 85.9 % of TOC removal were observed. Moreover, the toxicity of the initial sample was reduced by 72.9 %. Interestingly, the catalytic oxidation of MO was not affected due to the presence of NaCl. Radical studies confirmed that SO4−⦁ radical was the major active species responsible for MO degradation. Subsequently, the central composite design (CCD) approach was used to find out the interaction effects between MO concentration (10–250 mg/L), PS dosage (50–500 mg/L), and MW treatment time (5–20 min) on MO removal. The CCD based response surface model was found to be significant and reliable (p < 0.0001). Moreover, the chemical cost and energy cost for MW/ZrO2/PS experiments under optimized condition was estimated as $22.5 and $30.3 per kg of MO removal. Overall, transition metal-based PS activation under MW irradiation could be one of the potential alternatives for dye wastewater treatment.

Unraveling a novel microwave strategy to fabricate exposed {001}/{101} facets anatase nanocrystals: Potential for use to the elimination of environmentally toxic metronidazole waste

This study present a novel microwave strategy to fabricate highly active anatase particles, exposing {101} and {001} facets. Microwave treatment time was shown to determine the growth of crystals in a certain direction. To the best of our knowledge, it is the first report revealing that the contact time of TiO2 crystals with fluorine ions during the microwave process affects the formed morphology, in particular exposed facets ratio. The important element of this study was a parallel approach to produce active photocatalysts and a convenient UV-LED light source. The simultaneous use of synthesized anatase nanocrystals with exposed {001}/{101} facets and tailor-made LED photoreactor led to the enhanced elimination of metronidazole. Photocatalytic studies showed greater activity in the elimination of metronidazole with increasing microwave exposure time, which was associated with the presence of the surface heterojunction {001}/{101}, leading to better separation of charge carriers.

Effect of Microwave Treatments Combined with Hot-Air Drying on Phytochemical Profiles and Antioxidant Activities in Lily Bulbs (Lilium lancifolium).

Lily bulbs (Lilium lancifolium Thunb.) are rich in phytochemicals and have many potential biological activities which could be deep-processed for food or medicine purposes. This study investigated the effects of microwaves combined with hot-air drying on phytochemical profiles and antioxidant activities in lily bulbs. The results showed that six characteristic phytochemicals were identified in lily bulbs. They also showed that with an increase in microwave power and treatment time, regaloside A, regaloside B, regaloside E, and chlorogenic acid increased dramatically in lily bulbs. The 900 W (2 min) and the 500 W (5 min) groups could significantly suppress the browning of lily bulbs, with total color difference values of 28.97 ± 4.05 and 28.58 ± 3.31, respectively, and increase the content of detected phytochemicals. The highest oxygen radical absorbance activity was found in the 500 W, 5 min group, a 1.6-fold increase as compared with the control (57.16 ± 1.07 μmol TE/g DW), which was significantly relevant to the group's phytochemical composition. Microwaves enhanced the phytochemicals and antioxidant capacity of lily bulbs, which could be an efficient and environmentally friendly strategy for improving the nutrition quality of lily bulbs during dehydration processing.

Inactivation of Escherichia coli in an Orange Juice Beverage by Combined Ultrasonic and Microwave Treatment.

The inactivation of Escherichia coli is one of the major issues in the food industry. The present study focuses on the application of a combined microwave-ultrasound system for the optimization of the inactivation of Escherichia coli ATCC 25922 in an orange juice drink. Using response surface methodology (RSM), trials were planned with a Box-Behnken Design (BBD) to maximize the impact of microwave power (A: 300-900 W), microwave treatment time (B: 15-35 s), and time of ultrasound (C: 10-30 min) on E. coli inactivation. Analysis of variance (ANOVA) was carried out and E. coli inactivation was expressed with a mathematical equation depending on the factors. The results showed that both the microwave treatment time and the time of ultrasound were effective as independent variables in eliminating the E. coli strain. However, the effect of these two variables, ultrasound and microwave exposure time, in combination was significantly greater than when examined separately. RSM modeling determined that optimal treatment conditions include 900 W microwave power, 33 s microwave treatment time, and 20 min time of ultrasound to achieve an 8-log reduction of E. coli, constituting total inactivation. The results of this study showed that ultrasound-microwave treatment is a potential alternative processing method for an orange juice beverage.

Microwave-Treated Physically Cross-Linked Sodium Alginate and Sodium Carboxymethyl Cellulose Blend Polymer Film for Open Incision Wound Healing in Diabetic Animals-A Novel Perspective for Skin Tissue Regeneration Application.

This study aimed at developing the microwave-treated, physically cross-linked polymer blend film, optimizing the microwave treatment time, and testing for physicochemical attributes and wound healing potential in diabetic animals. Microwave-treated and untreated films were prepared by the solution casting method and characterized for various attributes required by a wound healing platform. The optimized formulation was tested for skin regeneration potential in the diabetes-induced open-incision animal model. The results indicated that the optimized polymer film formulation (MB-3) has significantly enhanced physicochemical properties such as high moisture adsorption (154.6 ± 4.23%), decreased the water vapor transmission rate (WVTR) value of (53.0 ± 2.8 g/m2/h) and water vapor permeability (WVP) value (1.74 ± 0.08 g mm/h/m2), delayed erosion (18.69 ± 4.74%), high water uptake, smooth and homogenous surface morphology, higher tensile strength (56.84 ± 1.19 MPa), and increased glass transition temperature and enthalpy (through polymer hydrophilic functional groups depicting efficient cross-linking). The in vivo data on day 16 of post-wounding indicated that the wound healing occurred faster with significantly increased percent re-epithelialization and enhanced collagen deposition with optimized MB-3 film application compared with the untreated group. The study concluded that the microwave-treated polymer blend films have sufficiently enhanced physical properties, making them an effective candidate for ameliorating the diabetic wound healing process and hastening skin tissue regeneration.

Effects of Microwave Treatment Time on the Quality of Soybean High-temperature Defatted Soybean Meal

Effects of Microwave Treatment Time on the Quality of Soybean High-temperature Defatted Soybean Meal

Combined Effect of Ultrasound and Microwave Power in Tangerine Juice Processing: Bioactive Compounds, Amino Acids, Minerals, and Pathogens

The inhibition of Escherichia coli ATCC 25922 (E. coli), Staphylococcus aureus ATCC6538 (S. aureus), Salmonella Enteritidis ATCC 13076 (S. Enteritidis), and Listeria monocytogenes DSM12464 (L. monocytogenes) is one of the main aims of the food industry. This study was the first in which the use of ultrasound and microwave power were applied to optimize the values of the bioactive components, amino acids, and mineral compositions of tangerine juice and to inhibit Escherichia coli, Staphylococcus aureus, Salmonella Enteritidis, and Listeria monocytogenes. The response surface methodology (RSM) was used to describe the inactivation kinetics, and the effects of ultrasound treatment time (X1: 12–20 min), ultrasound amplitude (X2:60–100%), microwave treatment time (X3: 30–40 s), and microwave power (X4:200–700 W). The optimum parameters applied to a 5-log reduction in E. coli were determined as ultrasound (12 min, 60%) and microwave (34 s, 700 W). The optimum condition ultrasound–microwave treatment was highly effective in tangerine juice, achieving up to 5.27, 5.12, and 7.19 log reductions for S. aureus, S. Enteritidis, and L. monocytogenes, respectively. Ultrasound–microwave treatment increased the total phenolic compounds and total amino acids. While Cu, K, Mg, and Na contents were increased, Fe and Ca contents were lower in the UM-TJ (ultrasound–microwave-treated tangerine juice) sample. In this case, significant differences were detected in the color values of ultrasound–microwave-treated tangerine juice (UM-TJ) (p &lt; 0.05). The results of this study showed that ultrasound–microwave treatment is a potential alternative processing and preservation technique for tangerine juice, resulting in no significant quality depreciation.

Effect of time and wattage power levels of microwave treatment on the microbial quality and safety of bovine raw milk

Raw milk is sterile when secreted by healthy cows, however it is contaminated with different microorganisms and Streptococci commonly present in the milk ducts as well as teats. The bacterial count in raw milk ranges from a few hundred to several thousand per mL of milk, however it is harmful to human health under unpasteurized condition. Milk sanitization methods rely on the principle of preventing the growth and development of microbes and thus maintaining their nutritional quality. This study was carried out to investigate the effect of microwave radiation on the microbial quality and safety of bovine raw milk. To do so, the effect of microwaves at a frequency of 35 KH and powers of 180, 300 and 850 W for 0, 30, 60 and 90 s on the destruction of pathogens and reduction of microbial load of milk (total bacterial count, coliforms, Escherichia coli, Staphylococcus aureus, molds and yeasts) was investigated. The results showed that microwave treatment had a significant effect on reducing the number of microorganisms in milk samples (p&lt;0.0) with the power of 850 W being the most effective power for reducing the number of S. aureus, coliforms, molds, yeasts as well as total bacterial count. Faster heating with higher energy efficiency is the main advantage of the microwave process for foods. In fact, the microwave method can be a potential and effective method for decreasing the microbial load of raw milk.

Study on Microwave Curing of Unsaturated Polyester Resin and Its Composites Containing Calcium Carbonate.

Microwave curing technology has been widely used in resin and its composite materials. In order to study its effect for curing unsaturated polyester resin (UPR) composites containing calcium carbonate (CaCO3) filler, this paper first investigated the influence of microwave power and microwave irradiation time on the curing characteristics of UPR. Then, CaCO3 particles were added to the UPR to investigate the microwave curing effect of the UPR composites containing the CaCO3. The results showed that microwave irradiation could heat the UPR sample evenly, and rapidly cause the chain growth reaction, thus greatly shortening the curing time. The curing degree and products of the samples after microwave curing were consistent with that of the thermal curing. The addition of CaCO3 particles could increase the heating rate of the UPR composites, which would accelerate the curing rate of the UPR. However, higher microwave power could lead to pore defects inside the UPR composites with higher CaCO3 content, resulting in a lower strength. Thus, the compactness of the samples should be improved by reducing the microwave power and prolonging the microwave treatment time.

Effect of Microwave Treatment on Adzuki Beans (Vigna angularis L.) under Dry State-Analyzing Microstructure, Water Absorption, and Antioxidant Properties.

In this study, a microwave was used on adzuki beans (Arari and Geomguseul) without water, in order to investigate their changes in microstructure, water absorption, and antioxidative properties. As the microwave treatment time increased (2450 MHz, 0 to 60 s), the lightness, redness, and yellowness were reduced, and moisture content significantly decreased in both varieties. The microstructure space between the seed coat, cotyledon, and pores within the cotyledon were observed, due to the loss of moisture. Regardless of microwave treatment, the water absorption behavior of the adzuki beans was sigmoidal. However, the water absorption kinetics of Arari increased after microwave treatment, whereas with microwave-treated Geomguseul, the water absorption rate decreased, compared to the control, except for the sample treated for 30 s. During soaking, the water absorption and softening rates in the microwave-treated adzuki bean were twice as fast as the untreated beans. Antioxidant activity, total phenolic compounds, and total flavonoid compounds were greatly improved by microwave treatment. These results indicate that microwave treatment affects the color, hydration, and bioactive compounds, and it can be used as a pretreatment method before processing adzuki beans.

Preparation and Characterization of Dual-Modified Cassava Starch-Based Biodegradable Foams for Sustainable Packaging Applications.

Starch and its derivatives have recently emerged as a sustainable and renewable alternative for petroleum-based expanded polystyrene (EPS) and expanded polypropylene (EPP) foam materials. In this study, biodegradable foam materials were prepared from cassava starch using a novel dual modification technique, combining microwave treatment and freeze-drying. The foam materials were prepared from starch solutions microwaved over different intervals. The starch-based foam materials were characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), 13C nuclear magnetic resonance (13C-NMR) spectroscopy, and compression set test. Moreover, the water absorption capacities and density values of the foam materials were measured according to ASTM standards. The biodegradability test was carried out according to the aerobic compost environment test. The lowest water absorption capacities of 65.56% and 70.83% were exhibited for the cassava starch foam sample (MWB) prepared at a 20 s microwave treatment time and immersed in distilled water for 2 and 24 h, respectively. Furthermore, the lightweight cassava starch-based foam materials displayed density ranging from 124 to 245 kg/m3. The biodegradation test exhibited significant biodegradation of over 50% after 15 days for all the foam materials prepared. These results suggest that the dual-modified cassava starch-based biodegradable foams show potential in sustainable packaging applications by replacing petroleum-based materials.

Numerical analogy of bioheat transfer and microwave cancer therapy for liver tissue

AbstractA numerical study of microwave cancer therapy for cylindrical‐shaped liver tissue with an elliptical‐shaped liver tumor has been carried out by this study. The time‐dependent electromagnetic wave and the bio‐heat transfer equations have been used as the governing equations and solved with appropriate boundary conditions using Galerkin's weighted residual scheme built‐in finite element method‐based COMSOL Multiphysics software. The coaxial applicator as well as the effects of different microwave input power levels (from 5 to 25 W), frequencies (from 0.7 to 5 GHz), and treatment time (from 0 to 1000 s) on hepatocellular carcinoma have been examined by this simulation and displayed graphically in terms of the microwave power dissipation, isothermal lines inside liver tissue, time‐dependent profiles of temperature at different locations inside the tumor, specific absorption rate (SAR), and surface average transient temperature distribution of tumor tissue. The results demonstrate that microwave input antenna power and frequency have significant impacts on the temperature distribution and SAR values of liver tissue. When the microwave input power, as well as frequency, is increased, SAR and tissue temperature values also increase but the high temperature is harmful to healthy tissue. It is observed from the performed analysis that the mean temperature of the tumor cell is about 56.86°C at a time of 180 s using 10 W microwave input power and 2.45 GHz frequency.