Study of wicking behavior of water on woven fabric using magnetic induction technique

An apparatus for measuring the wicking rise of water in fabrics has been developed and several types of fabrics were examined. The method is based on the electromagnetic field induction due to wicking penetration of water into capillary spaces of fabric samples. The measuring system is coupled with a personal computer, and the distance of water rise as a function of time is determined. Plain woven fabric samples with different weft yarn counts, density, and type of fiber in blend yarn were examined. The results obtained by wicking measurement were compared with water vapor permeability index data and the test method for wettability of textile fabrics on the same samples. The average wicking rise of water decreases with the increase of weft yarn density. The wicking of water along the cotton–polyester blend weft yarn is higher than 100% cotton weft yarn samples. The relation of water vapor permeability (WVP) index and the test method for wettability of the same fabric samples show the same behavior as the wicking rise. The equivalent geometric factor neglecting the Earth’s gravitational field is calculated by the average slope L ²/t from the experimental data of wicking of water into the samples. The radii of open channels in the woven fabric sample tends to decrease as a result of increasing weft yarn density.     

EFFECT OF CENTRIFUGAL FORCE ON THE AQUEOUS EXTRACTION OF SOLUTE FROM SUGAR BEET TISSUE PRETREATED BY A PULSED ELECTRIC FIELD

In this article, the centrifugal aqueous extraction of solute from sugar beet tissue is investigated at ambient temperature after a pulsed electric field (PEF) treatment. Two kinds of samples of fresh sugar beet were used: a sample with a determined discoid shape and gratings. Both samples were pretreated by a PEF with 250 rectangular pulses of 100 µS each. The PEF intensity was fixed at 940 V/cm for the disk samples and 670 V/cm for gratings. The pretreated samples were placed in distilled water at ambient temperature with a water‐to‐solid ratio equal to 3 and subjected to different centrifugal accelerations. The centrifugal field significantly enhanced the kinetics of extraction from the electrically pretreated tissues of sugar beet. However, the increase of centrifugal acceleration was only effective up to a certain value (5430 × g for disk samples and 600 × g for gratings). The centrifugal extraction can be assumed to proceed in two stages: a first rapid washing followed by a slow diffusion stage. A two‐exponential kinetics model taking into account these two stages was applied and correctly described the centrifugal extraction from beet samples (disks and gratings).     

Inactivation of L. plantarum in a PEF microreactor: The effect of pulse width and temperature on the inactivation

This article describes the inactivation of Lactobacillus plantarum by pulsed electric fields (PEF) in a microfluidic reactor. The microreactor has the specific advantage that the field intensity can be extremely high with accurate control and measurement of the pulse shape, combined with good temperature controllability. It is demonstrated that the temperature increase due to the ohmic heating of the fluid during treatment is marginal, thereby making this an excellent device for decoupling the temperature and electric field effects of PEF. Flow cytometry measurements showed that the electroporation of cells by PEF is a gradual effect. Reducing the pulsewidth at equal energy inputs did not show a change in inactivation. Higher temperatures showed higher inactivation rates. The effect of the temperature and the electric field strength could be described by a model that combines an Arrhenius equation for temperature dependency with either a Huelsheger or an activation energy based model for electric field dependency.Industrial relevanceThe product temperature is increasing during pulsed electric field treatment due to ohmic heating. Up to now, it was not possible to distinguish between the electric and heat effects that take place in the reactor. With the presented PEF microreactor, it was possible to make this distinction, which can help in the development of new, optimized PEF reactors.     

Modelling the inactivation of Escherichia coli ATCC 25922 using pulsed electric field

Microbial tests were conducted to determine the effect of pulsed electric field treatment on microbial inactivation of gram negative Escherichia coli ATCC 25922 suspended in simulated milk ultra filtrate (SMUF). Kinetic analysis of microbial inactivation due to combined pulsed electric field (PEF) and thermal treatments of E. coli was investigated. A generalized correlation for the inactivation rate constant as a function of both electric field intensity and treatment temperature was derived. Comparison between experimental and theoretical variation of E. coli concentration with time after PEF treatment in a complete recirculation mode was conducted using the inactivation kinetics developed from the single pass measurements.

Industrial relevance

PEF technology has a tremendous potential to replace thermal pasteurisation for products which are sensitive to temperature. In this work a pulsed electric field process was mathematically modelled and a generalized correlation for the inactivation rate constant as a function of electric field intensity and treatment temperature was derived. The correlation is needed for the design of industrial PEF systems.     

Impact of PEF treatment inhomogeneity such as electric field distribution, flow characteristics and temperature effects on the inactivation of E. coli and milk alkaline phosphatase

High intensity pulsed electric field (PEF) treatment was investigated focusing on the alteration of electric field distribution, flow characteristics and temperature distribution due to the modification of the treatment chamber. The aim was the improvement of the effectiveness of microbial inactivation of E. coli and to reduce the PEF impact on alkaline phosphatase (ALP) activity in raw milk. Mathematical simulation of the PEF process conditions considering different treatment chamber setups was performed prior to experimental verification. Finally the impact of the treatment chamber modifications on microbial inactivation and enzyme activity was determined experimentally. Using a continuous flow-through PEF system and a co-linear treatment chamber configuration the insertion of stainless steel and polypropylene grids was performed to alter the field strength distribution, increase the turbulence kinetic energy and improve the temperature homogeneity. The Finite Element Method (FEM) analysis showed an improved electric field strength distribution with increased average electric field strength and a reduced standard deviation along the center line of the treatment zone indicating a more homogenous electric field. The velocity profile was improved resulting in an increase of turbulence kinetic energy due to the insertion of the grids. As revealed by mathematical modeling, the temperature of the liquid was decreased, and formation of temperature peaks was avoided. Measured inactivation of heat sensitive alkaline phosphatase (ALP) was reduced from 78% residual activity to 92% after PEF treatment and it could be shown that thermal effects and temperature peaks have been the main reason for enzyme inactivation due to PEF. At the same time, an increase of microbial inactivation of 0.6 log–cycles could be determined experimentally due to the modification of the treatment chamber design.

Industrial relevance

The application of pulsed electric field as a non-thermal pasteurization technology requires an accurately defined treatment intensity followed by a predictable microbial inactivation. Unavoidable thermal effects occurring during PEF treatment due to ohmic heating have to be minimized to assure the retention of heat-sensitive nutrients and bioactive compounds. The presented investigations contribute to the fulfilment of these requirements for further successful industrial implementation of the PEF technology such as the selective inactivation or retention of enzyme activity in liquid food systems.     

Determination of Calcium Mobility in Alkaline‐Cooked Grounded Corn in Presence of a Magnetic Field

The mobility of calcium ions in corn dough prepared using commercial powder of alkaline‐cooked grounded‐corn kernel was determined in presence of a magnetic field. The ionic conduction was determined using 2 electrodes placed at 2 consecutives corners of the square samples: the excitation line was along one edge. Three different calcium concentrations [Ca] and 3 different magnetic field B conditions (B0, B?, B+) were analyzed; in all cases, the same amount of water was used. The relaxation times τ were determined by measuring the ionic current with and, immediately after, without excitation voltage. An empirical model, based on the obstruction effect characteristic of the ionic conduction and on the effect of the magnetic field B on the motion of the ions, was developed to explain the dependence of τ with [Ca] and B. The threshold concentration at which the Ca ions are not longer linked chemically to the starch molecules and move freely in the dough interior was obtained.     

混合磁悬浮织针驱动的永磁织针磁场分布规律

为研究横机织针混合磁悬浮驱动的空间磁场分布规律,通过构建圆柱形和长方体形2种永磁织针结构,根据安培环路定理,将永磁体等效为纵向的多圈电流环结构,并据此推导出织针垂直向上运动至空间任意位置的磁感应强度。在此基础上利用有限元电磁仿真软件对永磁织针模型进行仿真,同时搭建织针空间磁场强度实验测量平台进行数值测量。通过对比计算、仿真和实验测量发现:在圆柱型永磁织针中,厚径比越大,磁感应强度越大;在长方形永磁织针中,厚度不变磁感应强度随着长宽比增大而减小。     

Modeling within the Bayesian framework, the inactivation of pectinesterase in gazpacho by pulsed electric fields

The inactivation of pectinesterase (PE) activity in gazpacho (a Spanish ready-to-use cold vegetable soup) under pulsed electric fields (PEFs) was studied. Samples were exposed to 4 μs monopolar or bipolar square-wave pulses at 5–35 kV cm⁻¹ electric field intensity for up to 1500 μs and 200 Hz (temperature below 40 °C). Inactivation of PE was greater when treatment time and electric field intensity increased, and bipolar pulses were more effective inactivating PE than monopolar ones. Estimation of parameters and quantities involved in the tested models were performed within the Bayesian framework. The kinetic evolution of the enzyme was explained using a 3-parameter biexponential model based on a mechanism involving two irreversible consecutive steps. Rate constant k₁ was not dependent on neither electric field intensity nor pulse polarity. Rate constant k₂ and ratio between the activities of intermediate forms and the native ones of the enzyme Λ were affected by those conditions.     

FREQUENCY OF SALMONELLA, CAMPYLOBACTER, LISTERIA AND ENTEROBACTERIACEAE DETECTION IN COMMERCIALLY COOL WATER-WASHED SHELL EGGS

The effect of cool water washing on shell egg temperature and pathogen detection was examined. Three temperature schemes were utilized in commercial dual washer systems: (1) HH = 48.9C, 48.9C; (2) HC = 48.9C, 23.9C; and (3) CC = 23.9C, 23.9C. HH eggsmaintainedthe highest surface temperature (26.25C in‐line, 20.25C off‐line and 23.25C combined, P < 0.05). The lowest temperatures were found in the CC eggs (21.25C in‐line, 17.25C off‐line and 19.25C combined). The frequency of Enterobacteriaceae detection in shell and membrane emulsions was greatest for the CC eggs (P < 0.05 for in‐line and combined). There was no difference in Enterobacteriaceae detection for the off‐line facility. Salmonella was detected in three of 384 samples from the in‐line facility. They were found in HC (2) and CC (1) shell emulsions. Two of 384 samples were positive for Campylobacter from the in‐line facility (CC). Three wash water samples were positive for Listeria in the off‐line facility (1 HC, 2 CC). No pathogens were detected in the egg contents during this study. The results of this study indicate that warm followed by cool water washing has the potential of decreasing egg temperature while maintaining surface microbiology at an acceptable level.     

Modification of wool fibers by atmospheric pressure plasma treatment

Shrink‐proofing processing of wool fabrics by vacuum plasma treatment has been studied for many years. However, as a wool shrink‐proofing processing method, discharge treatment under atmospheric pressure, such as corona and low‐temperature electric plasma treatment, has been studied recently. In this study, an attempt was made to improve shrink‐proofing and other properties of a wool fabric by low‐temperature plasma treatment. The wool fabric was treated by pulsed atmospheric pressure plasma using a dielectric barrier discharge apparatus of the Institute of Textile Technology at Denkendorf by varying the power and flow rate of air. Shrink‐proofing, dyeing yield and water‐absorbing properties increased to a greater degree with the increase in the treatment time. However, the effect was saturated at 3 min. On the other hand, hysteresis of shearing property at large shear angle (2HG5), which is one of the mechanical parameters for measuring fabric hand by the Kawabata evaluation system (KES), becomes larger with the treatment time. It can be concluded that shear hysteresis value is related to the improvement in shrink‐proofing and other properties of the wool fabric.     

THERMOELECTROMAGNETIC COUPLING IN MICROWAVE FREEZE-DRYING

A coupled thermoelectromagnetic model of microwave freeze‐drying was developed by introducing the reflection coefficient method of the electromagnetic theory into the sublimation‐condensation model, to describe the coupling between the electromagnetic field strength distribution and the heat and mass transfer in microwave freeze‐drying. The experiments of beef were provided and the good agreement between the predicted and experimental results validates the model. The variations of the field strength, the temperature and the moisture content distributions during the microwave freeze‐drying process were discussed based on the model. The simulated results show that the microwave distribution in the cavity is a moving standing wave and that the actual field strength inside the material is less than that in the cavity. The nonuniform heating of the microwave will increase either the temperature in the dried region or the temperature in the frozen region, depending on the microwave input direction.     

RELATIONSHIP BETWEEN RHEOLOGICAL BEHAVIOR AND BOSTWICK MEASUREMENT DURING MANUFACTURE OF KETCHUP

ABSTRACT

The Bostwick consistometer remains an integral part of assessing the consistency of tomato products. For instance, the consistency of lots of tomato paste are designated at the factory by their Bostwick measurement; tomato ketchup is produced to meet Bostwick ranges given in U.S. Standards for Grades. This work addresses the blending of tomato pastes, at different Bostwick readings, for use in the remanufacture of ketchup. For both blends and ketchup, the Bostwick measurement was correlated to rheological parameters measured by two methods: a single‐point method and rotational viscometry. The correlations between the Bostwick measurement and the viscosity were compared with the theoretical prediction based on gravity current flow. The results illustrate that the relationship between the Bostwick measurement and (K/ρ)^?1/(2n+3) provides a means to predict the Bostwick length from at‐line or in‐line viscosity measurements.

PRACTICAL APPLICATIONS

The results of this work provide a means to predict the Bostwick length from at‐line or in‐line viscosity measurements. Specifically, the quantitative relationships presented in the article allow in‐line process control schemes to improve final product quality.

     

自动检重秤的电磁力补偿原理

<正> 电磁力平衡式称重技术是称重业界的一项新兴工艺,它是通过量度负载产品与称重传感器内的电磁力相比较,从而读出负载产品的重量。来自瑞士苏黎世的梅特勒—托利多集团以提供质优的工业衡器及分析仪器见称,并不断致力于产品开发。多年来,公司成功开发的电磁力补偿技术,不仅应用于实验室电子天秤,还有应用于工业高精度电子秤和在线动态检重秤等产品。旗下的Garvens Automation GmbH公司专门制造在线动态检重秤,并拥有先进的动态称重技术和精湛的制造工艺,他们揉合双方的优势而制造出崭新的电磁力补偿自动检重秤。     

Inactivation of Pectin Methyl Esterase in Orange Juice by Pulsed Electric Fields

ABSTRACT: Pulsed electric fields (PEF) treatments were applied to nonpasteurized orange juice using a bench top PEF system to study effects of PEF on the activity of pectin methyl esterase (PME). Effects of electric strength on PME activity at a constant water bath temperature were studied using electric field strengths up to 35 kV/cm at 30 °C. Increase of electric field strength caused a significant inactivation of PME with increase in orange juice temperature ( p < 0.05). A thermal inactivation study showed that heating of orange juice at the same temperature as orange juice during PEF treatment was not effective as PEF treatment in inactivating PME. Effects of electric field strength at different water bath temperatures were studied using electric field strengths up to 25 kV/cm and water bath temperatures of 10–50 °C. Higher electric field strengths at higher water bath temperature were the more effective to inactivate PME. A combination of PEF treatment at 25 kV/cm and a water bath temperature of 50 °C caused 90% inactivation of PME.     

Application of an In‐line Viscometer to Determine the Shear Stress of Plasticised Wheat Starch

An in‐line viscometer was designed and constructed to enable determination of the shear stress of plasticised wheat starch during extrusion cooking. The viscometer was installed between the end of the barrel section and the extruder die plate so that the shear stress could be determined for the plasticised material, irrespective of the geometrical shape into which it was subsequently moulded by the extruder die. The extrusion conditions were described in terms of the process parameters, i. e. water content, barrel temperature, screw speed and screw configuration; and of the system parameters, which were the specific mechanical energy input (SME), product temperature (PT) and mean residence time (MRT). The parameters were measured and the results evaluated using statistical methods. Regression equations were used to describe functional relationships between the shear stress and the extrusion conditions on the one hand, and between the shear stress and the product characteristics of the extrudates on the other. The shear stress of plasticised wheat starch determined in‐line can be used to predict the morphological structure (volumetric expansion) and the functional properties (cold paste viscosity and cold water solubility) of extruded, directly expanded starch with a high degree of accuracy. The measurement technique used and the results of the extrusion tests undertaken for this project will therefore enable the shear stress of plasticised material in an extruder to be used as the principle parameter for controlling extruders on‐line.     

交变电场在还原染料电化学还原染色中的增效作用研究

采用自制的间接电化学还原染色装置将还原艳绿FFB还原成隐色体钠盐,在染色过程中加以交变电场,从而促进还原染料隐色体上染纤维,研究了电场强度、温度和pH、染色时间对染色效果的影响。结果表明：在电场强度1600N／C、pH11．5、染色温度45℃的条件下染色,9min即可达到染色平衡,染色K／S值最高可达20．07,在相同染料浓度下较常规电化学还原染色和传统还原染料染色高,且湿摩擦牢度和皂洗牢度可提高0．5—1级。     

A pulsed electric field procedure for promoting Maillard reaction in an asparagine–glucose model system

Effects of pulsed electric field (PEF) on pH, intermediate products, asparagine and glucose content, browning value, reducing power as well as antioxidant activity of an asparagine–glucose solution were explored in this paper. Results showed that the solution’s UV–Vis absorbance at 294 nm and 420 nm was significantly increased from 0 to approximately 1.14 and 0.74, respectively, at PEF intensity of 40 kV cm^?1 for 7.35 ms treatment. The temperature of PEF treated samples were overall lower than 40 °C. It was also detected that the antioxidant activity of treated sample was correspondingly increased by 20.33%. Meanwhile, 14% reduction of asparagine content and 66% reduction of glucose content were observed. It was demonstrated from high performance liquid chromatography analysis that Maillard reaction in the model system had been enhanced by PEF treatment as no 5‐hydroxymethyl‐2‐furaldehyde was generated. This study indicates that pulsed electric field treatment, especially with higher intensities, is a means to significantly promote the Maillard reaction in an asparagine–glucose solution.     

Inactivation of bacillus subtilis by high intensity pulsed electric fields under close to isothermal conditions

Abstract

Because of expected nutritional, sensorical and health benefits, non‐thermal processing has the potential to satisfy the growing demand for minimally processed foods and can simultaneously provide safe and stable foods. Since the 60's the use of high intensity pulsed electric fields in food processing has repeatedly been demonstrated for e.g. pasteurization or cell permeabilization. The technical advance in the field of pulsed power equipment during the last years legitimates the approach of re‐considering some of these processes.

In this work the inactivation of vegetative Bacillus subtilis ATCC 9372 by high intensity pulsed electric fields was investigated in a batch treatment chamber. A switching system was used which allowed the application of square wave pulses with variable on‐time and a turn‐on rise time of less than 50 ns. Field strength from 2.5 to 52.8 kV/cm was investigated. The aim was to clearly discriminate between the effect of field strength and pulse energy without thermal interference.

It was found that inactivation is a linear function of field strength. A threshold field strength which has to be exceeded to achieve cell death was not observed. However, a minimum specific pulse energy was required to affect the micro‐organisms.     

Measurement of water activity with an electric hygrometer

Specific problems arising from the use of an electric hygrometer for measurement of water activity ( a _w) are the equilibration period, the calibration of the sensors and the influence of temperature on the values measured in saturated salt solutions and meat products. The instrument proved to be a simple, rapid and reliable means of measuring a _w values, provided some precautions are taken.     

荸荠汁欧姆加热特性及欧姆加热对其澄清度的影响

荸荠汁是重要的荸荠加工制品,但其澄清度不佳的问题显著影响了产品品质。本研究使用自制欧姆加热装置处理荸荠汁,以期获得荸荠汁的欧姆加热特性,并探索欧姆加热对荸荠汁澄清度的影响。结果表明:荸荠汁的电导率随着温度和电场频率的增加而增加;低频低电场强度下荸荠汁的温度随时间呈线性关系,高频高电场强度下则呈指数关系。同一电场强度下,荸荠汁的电导率随加热频率的增加而增加,其中在200和400 Hz时电导率约为50 Hz时的两倍。荸荠汁的容抗值主要是在-5~0 Ω之间波动,电场强度对其影响不显著(p>0.05)。欧姆加热后电位值下降到原值的50%左右,颗粒稳定性下降,更加易于荸荠汁的澄清。综合来看,欧姆加热对荸荠汁澄清度有一定改善作用。