食品高压脉冲电场杀菌技术

介绍高压脉冲电场杀菌的原理、设备装置、影响因素和杀菌效果。该技术离大规模商业化还有一定距离，需要科技工作者进一步研究。     

Current and future prospects for the use of pulsed electric field in the meat industry

Pulsed electric field (PEF) is a novel non-thermal technology that has recently attracted the attention of meat scientists and technologists due to its ability to modify membrane structure and enhance mass transfer. Several studies have confirmed the potential of pulsed electric field for improving meat tenderness in both pre-rigor and post-rigor muscles during aging. However, there is a high degree of variability between studies and the underlying mechanisms are not clearly understood. While some studies have suggested physical disruption as the main cause of PEF induced tenderness, enzymatic nature of the tenderization seems to be the most plausible mechanism. Several studies have suggested the potential of PEF to mediate the tenderization process due to its membrane altering properties causing early release of calcium ions and early activation of the calpain proteases. However, experimental research is yet to confirm this postulation. Recent studies have also reported increased post-mortem proteolysis in PEF treated muscles during aging. PEF has also been reported to accelerate curing, enhance drying and reduce the numbers of both pathogens and spoilage organisms in meat, although that demands intense processing conditions. While tenderization, meat safety and accelerated curing appears to be the areas where PEF could provide attractive options in meat processing, further research is required before the application of PEF becomes a commercial reality in the meat industry. It needs to deal with carcasses which vary biochemically and in composition (muscle, fat, and bones). This review critically evaluates the published reports on the topic with the aim of reaching a clear understanding of the possible applications of PEF in the meat sector in addition to providing some insight on critical issues that need to be addressed for the technology to be a practical option for the meat industry.     

高强脉冲电场对食品成分的影响

强脉冲电场是近年来发展起来的一项非热食品绿色加工新技术,有望取代传统热处理技术,从而引起了业内广泛关注。本文综述了强脉冲电场处理对液态食品品质和成分的影响,与热处理相比,强脉冲电场处理具有保存食品原有风味和营养价值的特性。      

高压脉冲电埸在食品加工中的应用前景

高压脉冲电场用于食品加工(杀菌、果蔬榨汁、成分提取等)已有很多研究,因其特有的微观作用机理.是一种非常有前景的新兴技术.综述了近十年来国内外用PEF处理食品的研究.对其进行分类介绍.讨论系统设计的要点.指出工业化需解决的几个问题.     

脉冲光在食品工业中的应用

文章综述一种新兴的非热方法——脉冲光的基本装置,分析其在多种食品基质中的作用机理和效果,并对可能存在的问题进行概括,为脉冲光在食品工业中的应用提供新的思考和见解。     

Numerical simulations of pulsed electric fields for food preservation: A review

The application of pulsed electric fields is a novel technique to preserve foods in a non-thermal way. One key component of this technology is the treatment chamber, in which the food is exposed to a pulsed electric field to induce permeabilization of biological cells, e.g. to inactivate microorganisms. For a high efficiency of the method and a high product quality a detailed knowledge of the electric field strength and temperature distribution in the chamber is necessary. The numerical simulation of the fluid dynamics coupled with the electric and thermal fields inside the treatment chamber can provide such information with high spacial and temporal resolution. An important goal of the simulations is the optimization of the treatment chamber geometry to improve the uniformity of the electric and thermal fields between the electrodes in order to avoid the over or under-processing of foods or dielectric breakdowns. This article reviews numerical investigations performed on the pulsed electric field process and presents numerical results of a treatment chamber optimization and the solution of coupled fluid dynamical, electrical and thermal problems.

Industrial relevance:

Numerical simulations of the pulsed electric field process provide detailed information of the fluid flow, the temperature and the electric field distributions in treatment chambers under various conditions. Such local information inside the electric field is difficult to obtain experimentally. For a further development of the pulsed electric field technology, numerical simulations can be applied to improve the fundamental understanding of the physical phenomena occurring and to optimize the process with respect to the chamber design and operating conditions.     

Effects of pulsed electric fields on cell membranes in real food systems

High frequency current and voltage measurements were used to determine passive electrical properties, such as the polarization effect at intact membrane interfaces and field-induced electropermeability changes in the cellular materials during direct current pulses. The time sequence of the electropermeabilization at the level of the cell membrane showed a similarity to the breakdown phenomena observed in cell systems (potato, apple and fish tissues, as well as plant cell suspension cultures) when a single pulse with critical or supercritical field amplitude is applied. A slight membrane breakdown phenomenon occurred in the first few microseconds after the initiation of the pulse at a critical electric field strength of 150–200 V/cm. Significant membrane breakdown was observed when the field strength of the electric pulses applied directly on the cell systems was in the range of 400–800 V/cm. At various field intensities, the electrical potential across a cell membrane reached a critical value of approximately 0.7–2.2 V. The initiation of conductive channels across the membrane occurred within nanoseconds during the charging process of the membrane, whereas the formation of a high-conductance membrane due to pore expansion took place within a few microseconds. The application of a single pulse, even with supercritical field amplitude, does not necessarily cause an irreversible membrane rupture. The insulating properties of the cell membrane can be completely recovered within several seconds after the termination of the pulse. The biological and engineering aspects of the membrane permeabilization are discussed in this paper. These data are utilized as the basis for the design and optimization of high-intensity pulsed electric field applications in the areas of food science and biotechnology.     

微波灭菌在食品工业中应用研究现状

为了推广微波在食品加工中的应用,通过微波灭菌的原理,介绍了几年来微波灭菌在不同食品体系中的应用研究,说明了微波灭菌对食品品质和营养价值的影响,认为微波灭菌是一种适应范围非常广的灭菌方法,可在多种食品加工中应用,和传统的灭菌方法相比,具有速度快、有利于保持食品的营养成分等优点.     

Applications of electricity and specifically pulsed electric fields in food processing: Historical backgrounds

Starting from two-three decades ago pulsed the electric field (PEF) treatment became very popular in a food industry. Many important effects and mechanisms related with impact of PEF on bio-, food or agricultural products have been discovered and elucidated for this period. Concept of electroporation has been fundamentally developed. The positive effects of PEE-assisted processing for inactivation of microorganisms, extraction, pressing, osmotic dehydration, drying, and freezing have been observed. Recent development and success of PEF applications has been also supported by the growing number of commercially available PEF generators with different characteristics, power and particular protocols. In the current paper, research works and applications of electricity and specifically pulsed electric fields in food processing over the period until the middle of the 1990s are summarized. A historical overview is presented in two steps devoted to: (a) the early studies on impact of electricity on growth, vegetation and germination and treatment of food by electricity before the 1940s and (b) the development of concept of selective electroplasmolysis and the first attempts to use the electricity and specifically the PEF treatment in food industry in the period between the 1940s ;and 1990s.Industrial relevanceDuring the long history of testing of electricity and specifically the PEF treatment in industrial relevant processing the serious problems and obstacles were revealed. Many pilot scale constructions were proposed and tested during the period between the 1940s and until the middle of the 1990s by different investigators from West Germany and USSR (Ukraine and Moldova). However, finally that technology was not industrialised due to the technical difficulties, the absence of necessary financial support and the lack of knowledge about basic mechanisms responsible for the impact of PEF. This historical experience can be very instructive for the development of modern applications of PEF technology in food industry.     

高压脉冲电场对食品中生物大分子的影响

高压脉冲电场非热处理技术因处理时间短、温升小、能耗低和杀菌效果明显等成为目前杀菌工艺中研究最为活跃的技术之一,而且在功能物质提取与保持物质活性等方面也展现了较好的应用前景。着重就高压脉冲电场对食品中的一些生物大分子如酶类、蛋白质等的影响进行综述。     

Metrology system for pulsed electric fields processing

Efficient process monitoring and accurate measurement of the electrical parameters defining pulsed electric fields (PEF) treatment and lethality are key factors in the implementation of PEF. A metrology system that can accurately evaluate and record treatment delivery was developed. To achieve this end one current sensor and two high voltage sensors were placed in a food PEF coaxial treatment chamber, grounded and shielded to minimize noise pick up due to electromagnetic interference, and connected to a digital oscilloscope to register PEF pulses. A graphical computer program was developed to control the oscilloscope and conduct data acquisition, measurement, and keep a data record of the electrical parameters defining the process: peak current, peak voltage, electric field, pulse width, and energy delivered. The program allows real-time calculation of the electrical parameters and reports all measurements with their uncertainties, which were evaluated with an uncertainty propagation analysis of the whole system. The metrology system was tested during PEF processing of a saline solution (σ=0.47 S/m at 20 °C) using a pilot plant pulse generator. The relative uncertainties reported range from 1.3 to 13.5%. The experimental results showed good agreement when compared with those simulated by PSpice™ software. Also, the calculated energy density applied to the saline solution correlated to its temperature rise, within 1 °C. The methodology followed in this research and the metrology system developed can be extrapolated and implemented in industrial scale PEF systems to monitor and keep data records of the PEF process.     

表面活性剂及其在食品工业中的应用

从表面活性剂的定义、分类出发,阐述表面活性剂的主要功能(増溶、乳化、润湿功能),及其在食品工业中的应用(在饮料、调味品、奶糖、糕点、食品检测、功能食品和微胶囊技术中的应用),以及作为脂肪替代品等方面的应用研究进展,同时也对表面活性剂的研究方向和发展趋势作了展望。     

高压脉冲电场对食品中微生物、酶及组分影响的研究进展

综述近10年高压脉冲电场(PEF)对食品中的微生物、酶和组分影响的研究进展.概述PEF对各种微生物的杀灭效果,着重阐述最近国际学者提出的PEF损伤亚致死微生物的存在;总结PEF对食品中重要酶的活力与二、三级等高级结构的影响;介绍PEF对食品中蛋白质、脂质、碳水化合物及其它组分的影响;总结分析目前的研究进展,认为尚需从分子水平深入研究PEF杀菌钝酶机理及其对食品组分的影响机制.     

Plant stress physiology: opportunities and challenges for the food industry

We review and analyze the possible advantages and disadvantages of plant-stress-related metabolic and structural changes on applications in the fruit and vegetable processing industry. Knowledge of the cellular and tissue transformations that result from environmental conditions or industrial manipulation is a powerful means for food engineers to gain a better understanding of biological systems in order to avoid potential side effects. Our aim is to provide an overview of the understanding and implementation of physiological and biochemical principles in the industrial processing of fruits and vegetables.     

An investigation on pulsed electric fields technology using new treatment chamber design

A pulsed electric field (PEF) system was designed and constructed using modern IGBT technology. The main focus of this work was to design a new PEF treatment chamber that operate at high electric field intensities with limited increase in liquid temperature and limited fouling of electrodes. Four multi-pass treatment chambers were designed consisting of two stainless steel mesh electrodes in each chamber, with the treated fluid flowing through the openings of the mesh electrodes. The two electrodes are electrically isolated from each other by an insulator element designed to form a small orifice where most of the electric field is concentrated. Dielectric breakdown inside the chambers was prevented by removing the electrodes far from the narrow gap. The effect of PEF treatment on the inactivation of gram-negative Escherichia coli ATCC 25922 suspended in simulated milk ultra-filtrate (SMUF) of 100%, 66.67% and 50% w/w was investigated. Treatments with the same electrical input power but with higher electric field strengths provided larger degree of killing. The effect of PEF treatment using suspensions at different flow rates and different pulse frequencies was also investigated. In general, the inactivation rate of E. coli increased with increasing electric field strength, treatment time and processing temperature. More than 6 log reductions in E. coli suspended in SMUF was achieved using electric field intensity in the range of (37.2–49.6 kV/cm) with a treatment temperature not exceeding 38 °C.Industrial relevanceThis paper presents an innovative pulsed electric field system for non-thermal pasteurisation of liquid food. The system design provides uniform distribution of electric field and minimum fouling of electrodes. This PEF system can be scaled up to any industrial size, making it attractive for industrial applications.     

新型食品添加剂增稠剂-可得然胶在食品工业中的应用

可得然胶是由微生物从葡萄糖中生成的发酵多糖类物质,在我国可作为食品添加剂增稠剂使用.它具有既能形成热不可逆性凝胶,又能形成热可逆性凝胶的独特特性,同时具有高热稳定性、耐冷冻冻性和成胶条件单一等特性.本文研究了可得然胶在食品工业中使用的温度条件、溶解条件、获取不同凝胶强度的不同成胶条件,以及研究了可得然胶在食品工业中的两类应用,即分别探讨了可得然胶在食品系统中的辅助性应用及结构性应用的原理及应用实例.     

Liquid food pasteurization by pulsed electric fields: dimensionless analysis via Sherwood number for a comprehensive understanding

Pasteurization of liquid foods by pulsed electric fields has been a subject of research for many years. The biological membranes are damaged by the process of electroporation, allowing leakage of internal compounds and possibly leading to subsequent cell lysis. This work is a continuation and extension of a former study that correlated biological inactivation with a modified Sherwood number. The Sherwood number is normally used to describe mass transfer under an electromotive force. In the present work, the Sherwood model was modified; the electric field intensity E was replaced by the specific energy W _specif a more general parameter, particularly when the chamber design results in a non-constant electric field. To deal with particular parameters, the length of the treatment chamber was also introduced. Experimental results were compared with the results obtained via the new model we propose. In addition, the model was able to satisfactorily describe results previously published in the literature. The model proposed is thus suitable for describing microbial inactivation in various systems, according to the chamber geometry, hydraulic regimes, electric signal shapes and durations, and the types of microorganisms (yeast and rod bacteria).     

高压脉冲电场对油酸的影响

研究了高压脉冲电场处理(PEF)时油酸理化性质的影响及PEF处理过的油酸在贮藏过程中理化性质的变化.PEF处理过的油酸在贮藏过程中其折光系数、色泽等变化不大;PEF处理对油酸的酸价无显著影响;油酸的过氧化值随着PEF处理强度和贮藏时间的增加显著增大;反映二次氧化产物的羰基值在PEF处理后的一周内变化不大,但随后迅速升高;PEF处理过的油酸碘价在贮藏2d后有下降趋势.     

Kinetic model for the inactivation of Lactobacillus plantarum by pulsed electric fields

The kinetics of Lactobacillus plantarum inactivation by pulsed electric fields (PEF) was studied in two different growth stages (exponential and stationary), but in the same reference medium (0.6% peptone water). Electric field intensity and treatment time varied from 20 to 28 kV/cm and 30 to 240 micros, respectively. The experimental data showed that cells in the exponential growth stage were more sensitive to PEF treatment than those in the stationary stage. The inactivation data were adjusted to the Bigelow and Hülsheger models and the Weibull frequency distribution function, and constants were calculated for both growth stages in each model. The models were tested and their accuracy was assessed by using the Accuracy Factor. According to this parameter, the Weibull frequency distribution function gave better fittings for the inactivation by PEF than Bigelow or Hülsheger models. On the other hand, the Bigelow model gave a good accuracy factor and is simpler.