Pulsed electric field processing effects on flavor compounds and microorganisms of orange juice

The headspace flavor compounds of fresh squeezed orange juice processed by pulsed electric field (PEF) at 30 kV/cm for 240 or 480 μs, or heat at 90°C for 1 min were isolated by a solid phase microextraction (SPME) coating and separated by gas chromatography. The average losses of flavor compounds in orange juice processed by 240, 480 μs PEF and heat process were 3.0%, 9.0% and 22.0%, respectively (P < 0.05). The flavor loss was mainly due to vacuum degassing in the PEF process. The total plate counts of control, 240, 480 μs PEF, and heat processed orange juice were 5400, 21, 19, and 4, respectively. The yeast and mold counts of control, PEF for 240, 480 μs and heat processed orange juice were 2800, 15, 9, and 4, respectively. ©     

The effect of electrical processing on mass transfer in beetroot and model gels

The diffusion between solids and surrounding liquids has been studied under the influence of different electric field strengths varying between 0–1000 V m⁻¹, characteristic both of ohmic heating and Moderate Electric Field (MEF) processing. The rate of enhancement of mass transfer between slabs of beetroot and surrounding fluid has been studied at up to 60 °C, as a function of electric field strength and the orientation of the slab to the field. Enhancements in diffusion coefficient of up to a factor of 2 are seen, with decreased enhancement at higher temperature and when the electric field does not pass through the particle. Diffusion into gels has been studied and enhancement found only for alginate (an ionically set gel) and not for gelatin and egg albumin, that are thermally set gels.     

高场强脉冲电场在胡萝卜汁加工中应用的研究

研究高场强脉冲电场 (HEFP)的产生及其处理胡萝卜浆提高出汁率的机理 ,探讨处理后的胡萝卜汁的营养成分、外观、色泽、风味的变化情况。     

通电加热技术在食品加工中的应用

从通电加热技术的发展历史入手.阐述了该技术的原理和特点;并从电场、频率、物料本身等方面讨论了通电加热的各种影响因素及其作用机理;介绍了目前对该技术的研究成果,以及该技术在食品加工中的应用和广阔的发展前景.     

高压脉冲电场技术在食品加工中的应用

高压脉冲电场技术是近年来发展起来的一项新兴的非热加工技术,它具有传递均匀、处理时间短、能耗低、能有效保护食品营养成分和天然的色香味等特征,是目前非热处理食品技术中效果最佳、应用前景最好的技术之一。介绍了高压脉冲电场技术的基本情况、系统介绍了高压脉冲电场技术在食品加工中的应用,分析了高压脉冲电场技术在食品加工中存在的问题,进一步展望了其工业化前景。     

Impact of a pulsed electric field on damage of plant tissues: effects of cell size and tissue electrical conductivity

Efficiency of pulsed electric field (PEF) induced permeabilization at 293 K in selected fruit and vegetable plant tissues (apple, potato, carrot, courgette, orange, and banana) at electric field strength (E) of 400 V·cm(-1), 1000 V·cm(-1) and pulse duration (t(p)) of 1000 μs was studied experimentally. The mean cell radius (〈r〉) was within 30 to 60 μm, and the ratio of electrical conductivities of the intact and damaged tissues (σ(i)/σ(d)) was within 0.07 to 0.79 for the studied tissues. Electroporation theory predicts higher damage for tissue with larger cells; however, the direct correlation between PEF damage efficiency and size of cell was not always observed. To explain this anomaly, a theoretical Monte Carlo model was developed and checked for parameters typical for potato tissue. The model showed a strong dependence of PEF damage efficiency and power consumption (W) on σ(i)/σ(d) ratio. The optimum value of electric field strength (E(opt)) was an increasing function of σ(i)/σ(d), and plant tissues with high σ(i)/σ(d) ratio (σ(i)/σ(d) ≈ 1) required application of a rather strong field (for example, E(opt) ≈ 3000 V·cm(-1) for σ(i)/σ(d) ≈ 0.8). However, the PEF treatment at a lower field (E ≈ 400 V·cm(-1)) allowed regulation of the selectivity of damage of cells in dependence of their size. A good qualitative correspondence between experimental data and simulation results were observed.     

Pulsed electric field processing of foods: a review.

Use of pulsed electric fields (PEFs) for inactivation of microorganisms is one of the more promising nonthermal processing methods. Inactivation of microorganisms exposed to high-voltage PEFs is related to the electromechanical instability of the cell membrane. Electric field strength and treatment time are the two most important factors involved in PEF processing. Encouraging results are reported at the laboratory level, but scaling up to the industrial level escalates the cost of the command charging power supply and of the high-speed electrical switch. In this paper, we critically review the results of earlier experimental studies on PEFs and we suggest the future work that is required in this field. Inactivation tests in viscous foods and in liquid food containing particulates must be conducted. A successful continuous PEF processing system for industrial applications has yet to be designed. The high initial cost of setting up the PEF processing system is the major obstacle confronting those who would encourage the system's industrial application. Innovative developments in high-voltage pulse technology will reduce the cost of pulse generation and will make PEF processing competitive with thermal-processing methods.     

通电加热中电场强度对猪肉电导率的影响

利用通电加热装置对猪肉进行了通电加热装置,比较了不同电场强度对试样加热速率和电导率的影响,结果显示在其它条件一定的情况下,电场强度越大试样的加热速率就越快;电场强度的不同对试样的电导率略有影响,但影响不大。     

Model for the differentiation of temperature and electric field effects during thermal assisted PEF processing

A model was developed that enables the quantification of thermal and electric field effects during the pulsed electric field (PEF) inactivation of alkaline phosphatase (ALP) and lactoperoxidase (LPO) in milk as well as Escherichia coli in apple juice.     

The effects of electrical stimulation and ageing on beef tenderness

Seventeen beef carcasses from cattle with a range of breeds, ages and body conditions were used in this trial. The four treatments applied to each carcass were control (C), electrical stimulation (ES), ageing for 28 days (A) and electrical stimulation plus ageing for 28 days (ES + A). Post-mortem muscle pH was measured at 0, 0·5, 4 and 24h post-stimulation. Significantly lower muscle pH values (P < 0·01) were achieved by the stimulated carcass side sompared to the unstimulated side at 0·5 (pH 6·47 vs. 6·91) and 4 h (pH 5·96 vs. 6·44) post-stimulation.

Warner-Bratzler shear and taste panel methods were used to assess the tenderness of Longissimus dorsi muscle samples from each of the four treatments. The ES, A and ES + A treatments were significantly more tender (P < 0·01) than the control treatment. The ES and the A treatments resulted in a similar improvement in tenderness compared to the control. The ES + A treatment was significantly more tender (P < 0·01) than the ES treatment alone, but there was no significant difference in tenderness between the A and the ES + A treatments.     

The effect of electrical processing on mass transfer and mechanical properties of food materials

A range of potential applications of electrical fields in the food industry has been investigated over the last decades. In this work the effect of electrical fields on mass transfer rates of cellular and hydrogel based foods was studied. Moderate Electrical Fields (MEF) of a continuous alternating current (50 Hz frequency) at fields up to 1400 v/m were used. Results demonstrated that both electrical fields and thermal treatment had an enhancing effect the extraction of betanin from beetroot. Placing the sample at a position perpendicular to the electrical field was found to have an enhancing effect on the extraction. Application of MEF also appeared to enhance the rate at which rhodamine6G absorbed to hydrogels set with ions, with mass transfer increasing with an increasing electrical field. No significant mass transfer enhancement was observed for hydrogels that do not set ionically (e.g. gelatin and albumen)     

脉冲电场在固体食品加工中的应用

脉冲电场(pulsed electric field, PEF)技术被视为21世纪食品非热加工技术发展史上的里程碑之一。迄今为止, PEF已广泛应用于果汁、牛奶和液态蛋等液体食品的杀菌和钝酶,并朝着商业化道路前进。然而,与PEF在液体食品中的应用相比,其在固体食品中的应用还处于起步阶段。固体食品的表面虽然也富含微生物,但PEF处理这类食品对微生物的影响较小,因此不能将其应用于固体食品的杀菌保鲜。仅管如此, PEF诱导的细胞电穿孔使其可作为一种预处理方法 ,通过增加质量和能量传递效率的方式来进行辅助固体食品的干燥、冻融、烹饪等。因此,本文重点介绍基于PEF细胞响应的高品质食品加工应用,总结PEF处理室的特点及PEF预处理固体食品的相关机制。最后,本文探讨了PEF在固体食品加工中的主要障碍和前景,为PEF未来在食品行业的发展拓宽研究方向。     

低温脉冲电场杀菌新工艺

<正> 近来,不少食品的质量因细菌的存在而受到严重影响,甚至危害消费者的健康。这与食品的处理、包装及贮存方法是否正确有莫大关系,其中,产品的消毒是否彻底有效更是关键所在。无疑,传统高温消毒灭菌工艺的可靠性很高,然而,由于需要采用高温加热处理,对食品或饮料原有的味道、色泽、营养价值、质感和功能均有所影响。为了改善这种情况,一项新式的低温杀菌工艺为食品工业带来了另一个理想的选择——脉冲电场杀菌技术。     

酶在大豆蛋白加工领域的应用进展

以改性分离蛋白、大豆多肽、植物水解蛋白（HVP）为例,介绍了酶制剂在大豆蛋白加工领域的应用情况,并对未来的发展情况进行了展望。     

A modified hot processing strategy for beef: reduced electrical energy consumption in carcass chilling

A beef processing strategy for improving energy and labour efficiencies, modified hot processing (MHP), was developed in a research abattoir. The work reported herein investigated carcass chilling rates and electrical energy usage in the chilling of carcasses that were processed using this approach. The MHP procedure removes the lower value cuts from the dressed carcass along with associated bone and fat. The remaining high value meat (posterior carcass quarter) is chilled in the usual manner, while the low value cuts are immediately processed (e.g. reduced into pre-blended, salted, chilled meat for emulsion-type products; rendered; directly processed as fresh, hot-boned meat, etc.). Carcasses prepared by the MHP method were dissected to quantify the amounts of lean meat, separable fat and bone removed in the procedure. These data were used with a simple model to predict the amount of chilling energy that could be saved by applying MHP prior to chilling. Electrical power to operate a blast chilling facility containing carcasses that had been processed either by conventional processing or by MHP methods was monitored and recorded, and the resulting data was used to confirm the model result. The MHP procedure reduced the refrigeration load for beef chilling by as much as 51% (P < 0·05). The amount of chilling energy to be saved would depend upon the methods employed to further process the low value tissues, and was calculated to be no less than 7%. The time for the reduced MHP carcass quarters to chill to 10°C at the fat-muscle interface of the longissimus dorsi muscle (12/13 rib) was shorter for MHP carcasses than for conventional carcasses (5·77 h vs 7·08 h, respectively) (P < 0·05). However, the times to chill the deep hip location of MHP hind quarters and conventional beef sides were not significantly different (P < 0·05).     

Use of electrical stimulation, hot processing and carrageenan for processing low-fat ground beef patties

Three studies were conducted to determine the effects of electrical stimulation, hot processing and carrageenan usage on sensory, shear force and cooking properties of low-fat (5, 10%) beef patties. The right or left sides of beef carcasses assigned to electrical stimulation (ES) received 600 V pulsating current for 120 s. Non-stimulated (NS) sides were also included for comparisons. Sides subjected to hot processing (HP) were boned 90 min post-exsanguination. Cold processing (CP) was initiated 48 h post mortem. Formulations for the manufacture of patties included the use of carrageenan [none, 0.5% iota (ι), 0.5% kappa (κ)]. Patties from NSHP beef had higher pH and cooking yields, less shrink in patty dimensions during cooking and lower shear force values than patties from NSCP controls (P < 0.05). ES improved tenderness and juiciness of CP patties, while ESHP patties exhibited higher cooking yields than NSCP patties. Tenderness was improved in two of the three studies as a result of increasing the fat content from 5 to 10%. Use of ι-carrageenan provided improvements in tenderness and juiciness over patties receiving no carrageenan or κ-carrageenan. Processors should consider HP with 1.0% added salt (improved cooking yields, patty configuration, tenderness) and the use of ι-carrageenan (improved tenderness and juiciness) for low-fat beef patties.     

Invited review: The effects of processing parameters on the flavor of whey protein ingredients

Whey protein ingredients are used in a wide variety of products and are added primarily for nutritional benefits or functionality, not for flavor. However, the processes used to further refine fluid whey produce and encourage development of off-flavors that carry through to the final product. From the milk source to spray drying, each step contributes to the oxidation of lipids, which negatively affects flavor. An understanding of the sources of these flavor constituents and volatile compounds, as well as how they are formed during processing and handling, are important to eliminate or reduce undesirable flavors and for understanding how to best incorporate these ingredients into high-quality finished products.