Non-thermal Method Research Articles

초음파 절삭가공에 의한 절단면의 Burr 높이의 최적화 실험

Ultrasonic cutting technology that can perform micro-cutting is applied for convenience of work to cut out unnecessary parts of a clear aligner during the manufacturing process of transparent devices for orthodontics. Ultrasonic processing is not limited physically or chemically by the material of the workpiece because it is a non-thermal, non-chemical, and non-conductive method. Owing to these characteristics, it is suitable for processing brittle materials such as glass and ceramic regardless of electrical conductivity. An ultrasonic cutting system is produced by applying this ultrasonic cutting technology, and the heights of burrs on the cut surface of PETG sheets are included in the experiment. The burr height is measured by setting the cutting speed to 100, 300, 500, 700, and 900 mm/min, and the power to 50, 60, 70, 80, 90, and 100 %. Then the optimal conditions are derived.

The effect of ultra-high pretreatment on free, esterified and insoluble-bound phenolics from mango leaves and their antioxidant and cytoprotective activities

Ultra-high pressure (UHP) is a novel non-thermal pretreatment method in food processing for improving the extraction yield of polyphenols and functional properties. The present work investigated the phenolic profiles, antioxidant activities, and cytoprotective effects of the free, esterified, and insoluble-bound phenolic fractions from mango leaves before and after ultra-high pressure (UHP) treatment. UHPLC-Q-Orbitrap-MS/MS analysis resulted in the identification of 42 phenolic compounds in the different phenolic forms. UHP pretreatment could significantly influence the contents of total phenols, total flavonoids and individual compounds in the different phenolic fractions (p < 0.05). After UHP pretreatment, these phenolic fractions exhibited greater antioxidant activity, and inhibited reactive oxygen species production and cell apoptosis (p < 0.05). Meanwhile, IBP were the most potential antioxidative and cytoprotective ingredients. Therefore, UHP pretreated mango leaves with enhanced bioactivity could be used as biological agents in the health food industry to improve its application and economic values.

Thermosonication Combined with Natural Antimicrobial Nisin: A Potential Technique Ensuring Microbiological Safety and Improving the Quality Parameters of Orange Juice.

Currently, thermal pasteurisation (TP) remains the most widely applied technique for commercial orange juice preservation; however, a high temperature causes adverse effects on the quality attributes of orange juice. In order to explore a novel non-thermal sterilization method for orange juice, the impacts of thermosonication combined with nisin (TSN) and TP treatments on the quality attributes including microbial and enzyme inactivation and the physicochemical, nutritional, functional, and sensory qualities of orange juice were studied. Both TP and TSN treatments achieved desirable bactericidal and enzyme inactivation effects, and nisin had a significant synergistic lethal effect on aerobic bacteria in orange juice (p < 0.05). Additionally, TSN treatment significantly improved the color attributes of orange juice and well maintained its physicochemical properties and sensory quality. More importantly, TSN treatment significantly increased the total polyphenols content (TPC) and total carotenoids (TC) by 10.03% and 20.10%, increased the ORAC and DPPH by 51.10% and 10.58%, and the contents of total flavonoids and ascorbic acid were largely retained. Correlation analysis of antioxidant activity showed that the ORAC and scavenging ability of DPPH radicals of orange juice are mainly attributed to TC and TPC. These findings indicate that TSN shows great potential application value, which could guarantee the microbiological safety and improve the quality attributes of orange juice.

Curcumin-mediated sono/photodynamic treatment preserved the quality of shrimp surimi and influenced its microbial community changes during refrigerated storage

Shrimp surimi is widely acknowledged as a value-added shrimp product due to its delicious taste, rich flavor, and nutrition. However, the refrigerated shrimp surimi is prone to deterioration due to rapid microbial growth during storage. The present study sought to assess the effects of curcumin-mediated sono/photodynamic treatment on bacterial spoilage and shrimp surimi quality stored at 4 °C. The total viable count (TVC), microbiota composition, and quality parameters, including the total volatile basic nitrogen (TVB-N), thiobarbituric acid reactive substance (TBARs), and pH were investigated. The results showed that the spoilage bacteria in shrimp surimi rapidly increased with a surge on day 2 during refrigeration storage. The Psychrobacter and Brochothrix were identified as the Specific Spoilage Organisms (SSOs), which were also positively correlated with TVB-N and TBARs. The results further elucidated that the sono/photodynamic treatment could significantly inhibit the growth of SSOs on the surface and interior of shrimp surimi and delay shrimp surimi quality deterioration. In conclusion, the sono/photodynamic treatment as a non-thermal sterilization method could be a reliable and potential method for inactivating spoilage microorganisms and preserving shrimp surimi quality.

Inactivation of Staphylococcus aureus and Escherichia coli Biofilms by Air-Based Atmospheric-Pressure DBD Plasma.

Air-based atmospheric-pressure plasma is an effective non-thermal method in deactivating various kinds of microbial biofilms with several advantages, including high bactericidal efficiency and low treatment costs. Bacterial biofilm formation is a major determinant in establishment of bacterial infection and also resistance to antibacterial chemotherapy. This study aims to assess the anti-biofilm potential of air-based atmospheric-pressure DBD plasma against Staphylococcus aureus and Escherichia coli biofilms. The biofilms of Staphylococcus aureus and Escherichia coli were exposed to air-based atmospheric-pressure DBD plasma for up to 4min (control, 30s, 90s, 3min, and 4min) and their biofilm formation level, viability, and membrane integrity were determined. Based on the results, plasma exposure caused disruption up to 70% and 85% for S. aureus and E. coli biofilms, respectively. The biofilm disruption potential of air-based atmospheric-pressure DBD plasma was confirmed using the scanning electron microscopy (SEM). Besides, based on confocal laser scanning microscopy (CLSM), plasma exposure caused a significant bacterial inactivation and E. coli was found as more susceptible strain than S. aureus. In conclusion, atmospheric-pressure DBD plasma could be considered an efficient non-thermal approach against bacterial pathogenicity by biofilm disruption and thus prevention of infection establishment.

The effect of high pressure combined with moderate temperature and peptidoglycan fragments on spore inactivation

High pressure processing (HPP) is a promising non-thermal processing method for food production. However, extremely high pressure and temperature are often required to achieve spores inactivation and commercial sterilization using HPP. In this study, the combined treatment of HPP, moderate temperature, and peptidoglycan fragments (PGF) for spore inactivation was investigated. The combined treatment of 200 MPa and 1 mg/mL PGF at 80 °C for 20 min resulted in 8.6 log inactivation of Bacillus subtilis 168 and more than 5 log reductions of Clostridium sporogenes PA3679 spores, respectively. A strong synergistic effect on spore inactivation among HPP, PGF, and temperature was observed. By comparing the effect of the treatment on the fluidity of the inner membrane and structural change of spores using fluorescence assay, a probable inactivation mechanism was proposed. It was concluded that the spores were firstly triggered to enter the Stage I of the germination process by HPP and PGF, and then immediately inactivated by the mild heat. This novel processing method could be an alternative to ensure commercial sterilization in the food industry.

Development of Decontamination Treatment Techniques for Dry Powder Foods by Atmospheric-Pressure Nonequilibrium DC Pulse Discharge Plasma Jet

Dry powder food ingredients imported to Japan contain large amounts of viable bacteria and coliform bacteria, and we need a simple, low-cost, dry nonthermal decontamination method without spoiling nutrients, color, fragrance, and flavor. In this study, it is shown that the decontamination performance against viable bacteria and coliform bacteria is proportional to the plasma irradiation time when OH and O3 radicals are incident on the dry powder food ingredients placed in an atmospheric-pressure nonequilibrium DC pulse discharge Ar + O2 mixture gas plasma jet. Our study revealed that there is a correlation between the plasma irradiation time and DC pulse frequency increase and the decontamination effect on the general bacterial count.

Microbial inactivation in fresh and minimally processed foods by intense pulsed light (IPL) treatment.

The purposes of this study were to evaluate the inactivation effects of intense pulsed light (IPL) on indigenous and inoculated microorganisms in fresh and minimally processed foods and the industrial applicability of this nonthermal sterilization method. The samples were treated with IPL by varying the treatment time and voltage. The inactivation effect tended to increase as the treatment conditions increased. Further, indigenous microorganisms showed a lower inactivation level than inoculated microorganisms, E. coli ATCC 25922, due to the variability of indigenous microorganisms and their properties. Chopped garlic showed a higher E. coli inactivation effect (2.65 log reduction after 0.185J/cm2 of IPL) than peeled garlic (1.21 log reduction) due to its larger surface area. The manila clam showed a lower E. coli inactivation (0.93 log reduction) effect than squid (1.84 log reduction) due to its rougher surface. After the IPL treatment, there was no significant difference in temperature, moisture content, and color.

Pulsed field ablation – new perspective in atrial fibrillation therapy

Atrial fibrillation (AF) is one of the most important problems in cardiology. Thermal ablation therapies are “gold standard” to treat symptomatic patients. Despite the improvements, both success rate and safety are limited by their thermal nature. Pulsed filed ablation is a new non-thermal ablation method. It is based on the phenomenon of unrecoverable permeabilization of cell membranes caused by pulses of high voltage (irreversible electroporation). Several preclinical studies suggest its safety. Clinical trials published so far have showed high efficacy. Further studies especially with longer follow-up period are needed.

Irreversible electroporation versus radiofrequency ablation for hepatocellular carcinoma: a single centre propensity-matched comparison

Background and aims Irreversible electroporation (IRE) is a relatively new non-thermal ablative method for unresectable hepatocellular carcinoma (HCC). We aimed to compare the longer-term efficacy of IRE to the standard thermal technique of radiofrequency ablation (RFA) in HCC. Methods All patients who underwent IRE or RFA for HCC in our centre were identified and demographic and clinical data were analysed up until 1st March, 2020. Local recurrence-free survival (LRFS) was compared between groups after propensity score matching for age, gender, Child–Pugh grade, BCLC stage, lesion size and alpha-fetoprotein (AFP) level. Results A total of 190 HCC ablations (31 IRE and 159 RFA) were identified. After propensity score matching, we compared 25 IRE procedures (76% males, median age 62.4 years, median tumour size 20 mm) to 96 RFA procedures (84.4% males, median age 64.3 years, median tumour size 18.5 mm). LRFS did not differ between groups, with a 1-, 2- and 5-year LRFS of 80.4% (95% CI 55.8–92.2), 69.1% (95% CI 43.3–84.9) and 44.9% (95% CI 18.9–68.1%), respectively for IRE and 84.8% (95% CI 75.2–90.9), 71.3% (95% CI 58.3–81.0) and 52.1% (95% CI 35.4–66.4%), respectively for RFA (p = .63). There were no major procedure-related complications or deaths in either group. Conclusions Whilst IRE remains a relatively novel therapy for HCC cases where standard thermal ablation is contraindicated, the LRFS in our centre is comparable to that of RFA. IRE should therefore be considered as a treatment option in such cases when available before stage-migration to non-curative therapies such as transarterial chemoembolization (TACE).

Pulsed electric fields act on tryptophan to inactivate α-amylase

Enzyme inactivation is a common industrial step of food preservation. Conventional method is based on heating, thus reduce organoleptic property and virtues of the products. We propose a non-thermal method of enzyme inactivation based on pulsed electric fields. By comparing the effect of electric fields, heating and oxidation on alpha-amylase, we have shown that the electric field targets the active site of the enzyme via the tryptophan, resulting in a conformational disruption. An electric pulse of 2.5–12.5 kV/cm, 10 μs and 0.02–0.6 J, repeated at 1–30 Hz for a total applied energy of 1440 J, partially denatured alpha-amylase, reducing activity by up to 70%; however, this was not followed by protein aggregation, as observed for heat treatment to 70 °C. Those results brought new understanding on the mechanism of pulsed electric fields action on proteins, and might lead in new application in food industry or in medicine.

Characterization of atrial lesion safety and efficacy utilizing a circular catheter and the IRE generator with an in vivo porcine model

Abstract Funding Acknowledgements Type of funding sources: Other. Main funding source(s): Biosense Webster, Inc. Introduction/Objectives: Pulsed field ablation (PFA) is a non-thermal ablative method that delivers high voltage, very-short duration pulses that cause pore formation in the cytoplasmic membrane and cell death. The tissue selectivity of PFA is expected to reduce the risk of collateral tissue injury compared to radiofrequency catheter ablation (RFCA), while maintaining effectiveness. The objective of this study was to perform pulmonary vein (PV) isolation in a porcine model to characterize the safety and performance of a novel, fully-integrated biphasic PFA system. The system is comprised of a multi-channel generator, a variable loop circular catheter, and an integrated irreversible electroporation (IRE) mapping software module. Methods The study evaluated safety and efficacy of IRE in 8 healthy swine. First, to evaluate safety, multiple ablations were performed at various cardiac structures, including within the lumen of the right pulmonary vein (RIPV), at the right superior pulmonary vein (RSPV) ostium, and adjacent to the esophagus. Second, to evaluate efficacy, animals were recovered and followed for 30 (±3) days, then re-mapped. Gross pathological and histopathological examinations were performed to assess for procedural injury, chronic thrombosis, tissue ablation, depth of penetration, healing, and level of inflammatory response. Results All 8 swine survived for the 30 (±3) day follow up (FU) period. There were no acute (day of procedure) incidents of pulmonary vein narrowing of &amp;gt;70%, nor at 30 d follow-up (FU), even when ablation was purposefully performed directly deep to the ostium of the vein. No injury was seen grossly or histologically in the adjacent esophagus. All PVs were durably isolated as confirmed by bidirectional block at the 30 (±3) day re-map procedure, and histological examination showed complete, transmural necrosis around the entire circumference of the ablated section of the right PVs [Figure]. Conclusion(s): This pre-clinical evaluation of a fully integrated PFA system demonstrated effective and durable ablation of cardiac tissue and PV isolation with no collateral damage to adjacent structures. Notably, histological staining confirmed complete transmural cell necrosis around the circumference of the ostial PV at 30 days. Abstract Figure. PVI maps (A) histology (B) and safety(C)

Effect of cold plasma treatment on sterilizing rate and quality of kiwi turbid juice

AbstractPrevious studies have shown that cold plasma inactivated microorganisms located on a variety of food surfaces and food packaging materials under atmospheric pressure conditions; however, less attention has been paid to the impact of cold plasma on microorganisms in liquid food stuffs. The aim of the study is to evaluate the effect of cold plasma treatment on maintaining quality and the bactericidal effect of kiwi turbid juice, and obtain the optimal parameters. Kiwi turbid juice was treated with different treatment voltages, juice volumes, and discharge times. Tow principle components (chlorophyll and total phenols) were extracted by factor analysis and the cumulative contribution achieved was 87.017%. Three‐factor response surface methodology was used to analyze the interactions between the factors, and particle swarm optimization was used to search for the optimal parameters. The results showed that the established three‐index regression model was significant. At the optimal level of 12 kV treatment voltage, 18 ml juice volume, and 1 min discharge time, chlorophyll, total phenols, and bactericidal rate of the optimized test were 0.18 mg/g, 3.47 OD280/g, and 83.97%, respectively. This study provides key implications for applying cold plasma during kiwi turbid juice processing.Practical applicationsKiwi turbid juice is rich in nutrition, has high quality and good taste, which can greatly retain the flavor of fresh juice, and has a broad market development prospect. Sterilization is a key process in the production of kiwi turbid juice, Cold plasma processing is a potential nonthermal method which can enable extension of shelf life of kiwi turbid juice, yet retaining its freshness and organoleptic properties.

High-pressure in situ methods revealing the effect of pressure on glutathione structure

High-pressure processing is a nonthermal method of food processing that is widely used in sterilization and enzyme inactivation. Although some works on technological parameters and quality evaluation have been performed, the mechanism of high pressure on food is still unclear. Due to the complexity of food ingredients, a tremendously important tripeptide in food proteins, orthorhombic l-glutathione, was employed in this work. In addition, in situ methods such as high-pressure Raman, infrared, and X-ray diffraction were used to investigate the structural changes in the pressure range of 0–10 GPa. Experimental results showed that the sample underwent two phase transitions in pressure intervals of 1.8–2.2 and 4.1–5.3 GPa. In addition, the strength of the hydrogen bonds (NH⋯O; OH⋯O; SH⋯O; CH⋯O) also changed in the two pressure intervals. This work may have potential research value for revealing the mechanism of high-pressure processing on food proteins.

Forward osmosis concentration of milk: Product quality and processing considerations

Concentration of milk in the dairy industry is typically achieved by thermal evaporation or reverse osmosis (RO). Heat concentration is energy intensive and leads to cooked flavor and color changes in the final product, and RO is affected by fouling, which limits the final achievable concentration of the product. The main objective of this work was to evaluate forward osmosis (FO) as an alternative method for concentrating milk. The effects of fat content and temperature on the process were evaluated, and the physicochemical properties and sensory qualities of the final product were assessed. Commercially pasteurized skim and whole milk samples were concentrated at 4, 15, and 25°C using a benchtop FO unit. The FO process was assessed by monitoring water flux and product concentration. The color of the milk concentrates was also evaluated. A sensory panel compared the FO concentrated and thermally concentrated milks, diluted to single strength, with high temperature, short time pasteurized milk. The FO experimental runs were conducted in triplicate, and data were analyzed by single-factor ANOVA. Water flux during FO decreased with time under all processing conditions. Higher temperatures led to faster concentration and higher concentration factors for both skim and whole milk. After 5.75 h of FO processing, the concentration factors achieved for skim milk were 2.68 ± 0.08 at 25°C, 2.68 ± 0.09 at 15°C, and 2.36 ± 0.08 at 4°C. For whole milk, after 5.75 h of FO processing, concentration factors of 2.32 ± 0.12 at 25°C, 2.12 ± 0.36 at 15°C, and 1.91 ± 0.15 at 4°C were obtained. Overall, maximum concentration levels of 40.15% total solids for skim milk and 40.94% total solids for whole milk were achieved. Additionally, a triangle sensory test showed no significant differences between regular milk and FO concentrated milk diluted to single strength. This work shows that FO is a viable nonthermal processing method for concentrating milk, but some technical challenges need to be overcome to facilitate commercial utilization.

Dense phase carbon dioxide treatment of mango in syrup: Microbial and enzyme inactivation, and associated quality change

Dense phase carbon dioxide (DPCD) has been mainly explored as a new non-thermal pasteurization method for liquid foods. However, it's pasteurization efficacy absolutely needs to be further investigated for solid-liquid food mixtures, such as mango in syrup. This study aimed to investigate pasteurization and enzyme inactivation effects for DPCD treatment, and evaluate quality changes by comparing with traditional thermal pasteurization (TP) method. Optimal DPCD treatment (20 MPa, 60 °C, 30 min) was determined by conducting single factor and orthogonal experiments. Staphylococcus aureus CICC 10384 and Escherichia coli CICC 10003, which were selected as representative gram-positive and gram-negative pathogens in mango in syrup, could be completely inactivated by the optical DPCD treatment with initial concentrations of >8-log CFU/mL. Polyphenol oxidase and peroxidase activities could be completely inactivated after the optimal DPCD processing. Less adverse effect on pH and color, and higher amounts of vitamin C and total phenols of samples were observed after DPCD treatment when compared with TP treatment. The shelf-life of mango in syrup treated with DPCD was estimated to be <86 days (25 °C) based on an accelerated shelf-life testing (ASLT). This study demonstrated that DPCD treatment can be considered as a promising pasteurization technology for solid-liquid mixtures without exceedingly influencing their quality attributes.

Application of Pulsed Electric Field for Inactivation of Yeast S. cerevisiae in Apple Juice

Pulsed electric filed (PEF) is a non-thermal food preservation method as alternative to traditional thermal method. The effect of pulsed electric field (PEF) on inactivation of yeast Saccharomyces cerevisiae (S.cerevisiae) in apple juice containing different sugar concentration was studied. The results of this study have shown that, using PEF, the yeast could be inactivated at room temperature (20°C). The inactivation effect of PEF was dependent on pulse number, field strength, and pulse width as well as sugar concentration. Pulse numbers less than 20 pulses (at 12.6kV/cm) had no or very less effect on yeast inactivation. Increasing the pulse number up to 400 pulses resulted about 3 logs yeast inactivation. The most important factor for yeast inactivation was the field strength (10 to 30 kV/cm). Whereas, at 10.2 kV/cm and 100 pulses, less than 2 logs yeast inactivation could be achieved, was the yeast inactivation at filed strength of 30kV/cm and 100 pulses about 5 logs. At given field strength and pulse number, longer pulse width (1 to 2.5 μF) affected positively the inactivation of microorganism. In contrast, increasing the sugar concentration in apple juice higher than 20% negatively affected the inactivation of yeast during PEF treatment at given treatment conditions.

Simultaneous synthesis of graphite-like and amorphous carbon materials via solution plasma and their evaluation as additive materials for\xa0cathode\xa0in Li\u2013O2 battery

Cathode materials are essential for enhancing electrocatalytic activity in energy-conversion devices. Carbon is one of the most suitable cathodic materials for Li–O2 batteries owing to its chemical and thermal stability. Carbon materials synthesized from tributyl borate (TBB) using a nonthermal solution plasma method were characterized using x‐ray diffraction, Raman, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy, and x-ray photoelectron spectroscopy and were evaluated as additive materials for cathodes in a Li–O2 battery. Two separate carbon materials were formed at the same time, a carbon dispersed in solution and a carbon precipitate at the bottom of the reactor, which had amorphous and graphite-like structures, respectively. The amorphous carbon contained boron and tungsten carbide, and the graphite-like carbon had more defects and electronic conductivity. The crystallinity and density of defects in the graphite-like carbon could be tuned by changing the SP operating frequency. The Li–O2 battery with the amorphous carbon containing boron and tungsten carbide was found to have a high capacity, while the one with the graphite-like carbon showed an affinity for the formation of Li2O2, which is the desired discharge product, and exhibited high cycling performance.

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.