Inactivation of Saccharomyces cerevisiae Suspended in Orange Juice Using High-Intensity Pulsed Electric Fields

2004 ◽  
Vol 67 (11) ◽  
pp. 2596-2602 ◽  
Author(s):  
PEDRO ELEZ-MARTÍNEZ ◽  
JOAN ESCOLÀ-HERNÁNDEZ ◽  
ROBERT C. SOLIVA-FORTUNY ◽  
OLGA MARTÍN-BELLOSO
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Orange Juice ◽  
High Intensity ◽  
Pulse Width ◽  
Treatment Time ◽  
Membrane Damage ◽  
Bipolar Mode

Saccharomyces cerevisiae is often associated with the spoilage of fruit juices. The purpose of this study was to evaluate the effect of high-intensity pulsed electric field (HIPEF) treatment on the survival of S. cerevisiae suspended in orange juice. Commercial heat-sterilized orange juice was inoculated with S. cerevisiae (CECT 1319) (108 CFU/ml) and then treated by HIPEFs. The effects of HIPEF parameters (electric field strength, treatment time, pulse polarity, frequency, and pulse width) were evaluated and compared to those of heat pasteurization (90°C/min). In all of the HIPEF experiments, the temperature was kept below 39°C. S. cerevisiae cell damage induced by HIPEF treatment was observed by electron microscopy. HIPEF treatment was effective for the inactivation of S. cerevisiae in orange juice at pasteurization levels. A maximum inactivation of a 5.1-log (CFU per milliliter) reduction was achieved after exposure of S. cerevisiae to HIPEFs for 1,000 μs (4-μs pulse width) at 35 kV/cm and 200 Hz in bipolar mode. Inactivation increased as both the field strength and treatment time increased. For the same electric field strength and treatment time, inactivation decreased when the frequency and pulse width were increased. Electric pulses applied in the bipolar mode were more effective than those in the monopolar mode for destroying S. cerevisiae. HIPEF processing inactivated S. cerevisiae in orange juice, and the extent of inactivation was similar to that obtained during thermal pasteurization. HIPEF treatments caused membrane damage and had a profound effect on the intra-cellular organization of S. cerevisiae.

Inactivation of Microorganisms in Cloudy Ginkgo (Ginkgo biloba Linn.) Juice by Pulsed Electric Fields

2007 ◽  
Vol 13 (2) ◽  
pp. 83-90 ◽  
Author(s):  
H. Zhang ◽  
Z. Wang ◽  
R.-J. Yang ◽  
S.-Y. Xu
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Electric Fields ◽  
Treatment Time ◽  
Synergistic Effects ◽  
Pulsed Electric Fields ◽  
Bath Temperature ◽  
Microbial Inactivation ◽  
Plate Counts

Pulsed electric fields (PEF) were applied to neutral ginkgo cloudy juice to study the influence of the electric field strength, the treatment time and temperature on microbial inactivation. The results showed that microbial inactivation increased with the electric field strength, the treatment time and temperature. PEF treatment caused 3.39 and 4.44-log cycles reduction of coliforms and total plate counts, respectively, when pulse duration was 3 μs, the electric field strength 30 kV/cm, the treatment time 520 μs and the water bath temperature 15°C. Under the same conditions, the microbial shelf life of ginkgo cloudy juice was extended to 24 days at 4°C and 18 days at room temperature. A 3.7-log cycles reduction of the total yeast and mould counts was obtained by applying 390 μs of 30 kV/cm at 15°C.Yeast and mould cells were less resistant to PEF process than bacteria cells. The effect of heat generated during the PEF treatment was limited on microbial inactivation. Temperature and the induced heat by PEF had synergistic effects to microbial inactivation in cloudy ginkgo juice.

Treatment of nanosized TiO2-containing wastewater by simultaneous electrocoagulation/electrofiltration

2005 ◽  
Vol 52 (10-11) ◽  
pp. 377-381 ◽  
Author(s):  
G.C.C. Yang ◽  
C.C. Chuang
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Filtration Rate ◽  
Treatment Time ◽  
Oxygen Demand ◽  
Operating Conditions ◽  
Transmembrane Pressure ◽  
Crossflow Velocity ◽  
Nanosized Tio2

In this work, a simultaneous electrocoagulation/electrofiltration (EC/EF) treatment module was employed to treat nanosized TiO2-containing wastewater. Nanosized TiO2-containing wastewater was obtained and treated by a self-designed EC/EF treatment module. To evaluate the performance of this novel treatment module, the effects of electric field strength (EFS), transmembrane pressure (TMP), and crossflow velocity (CV) on permeate qualities were investigated. Permeate qualities of concern included pH, turbidity, conductivity, chemical oxygen demand (COD), and total organic carbon (TOC). A full factorial design of experiments was adopted in this work. First, by keeping TMP and CV constant the effects of EFS on permeate qualities were studied. In this set of testing, it was noticed that an application of electric field greatly increased the filtration rate, which was further influenced by the magnitude of EFS. In all cases, the filtration rate decreased as the treatment time elapsed due mainly to fouling of the membrane. Further tests were conducted to study the effects of TMP on permeate qualities by keeping EFS and CV constant. Finally, the effects of CV on permeate qualities were studied by keeping EFS and TMP constant. It was found that the optimal operating conditions would be electric field strength of 166.7V/cm, transmembrane pressure of 1kgf/cm2, and crossflow velocity of 0.22cm/s. Under such conditions, permeate would have the following qualities: (1) pH, 6.32; (2) turbidity, 2.41NTU; (3) conductivity, 15.11μS/cm; (4) COD, 100.0mg/L; and (5) TOC, 512.6mg/L.

Studies on the Microstructure and Thermal Properties of Pulsed Electric Fields (PEF)-Treated Maize Starch

2012 ◽  
Vol 8 (1) ◽  
Author(s):  
Zhong Han ◽  
Qian Yu ◽  
Xin An. Zeng ◽  
Dong Hui Luo ◽  
Shu Juan Yu ◽  
...  
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Electric Fields ◽  
Treatment Time ◽  
Dominant Role ◽  
Pulsed Electric Fields ◽  
Maize Starch ◽  
Scanning Calorimetry ◽  
Significant Difference

Maize starch-water suspensions (8.0%) were submitted to the pulsed electric fields (PEF) with different electric field strength and treatment time up to 50 kV/cm and 1272 μs. Samples were characterized by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and nuclear magnetic resonance (NMR). GPC analysis showed that molecular weights (Mw and Mn) were decreased with increasing electric field strength and treatment time. DSC studies showed a decrease in gelatinization temperatures (To and Tp) and the enthalpy of gelatinization (ΔHgel) with increasing electric field strength and treatment time. It was explored that electric field strength played a dominant role in the PEF treatments. On the other hand, it was demonstrated from NMR and TGA analysis that no significant difference among the native and PEF-treated maize starches was obtained, which indicated that PEF treatments did not affect the chemical structure of maize starch.

Increased Inactivation of Exopolysaccharide-Producing Pediococcus parvulus in Apple Juice by Combined Treatment with Enterocin AS-48 and High-Intensity Pulsed Electric Field

2010 ◽  
Vol 73 (1) ◽  
pp. 39-43 ◽  
Author(s):  
PILAR MARTÍNEZ VIEDMA ◽  
ANGEL SOBRINO LÓPEZ ◽  
NABIL BEN OMAR ◽  
HIKMATE ABRIOUEL ◽  
ROSARIO LUCAS LÓPEZ ◽  
...  
Keyword(s):  
Electric Field ◽  
High Intensity ◽  
Apple Juice ◽  
Cyclic Peptide ◽  
Treatment Time ◽  
Combined Treatment ◽  
Storage Period ◽  
Pulsed Electric Field ◽  
Bipolar Mode ◽  
The Stability

The cyclic peptide bacteriocin enterocin AS-48 was tested (at final concentrations of 0.175, 0.613, and 1.05 AU/ml) against the exopolysaccharide-producing cider spoilage strain Pediococcus parvulus 48 in apple juice in combination with high-intensity pulsed electric field (HIPEF) treatment (35 kV/cm and 150 Hz for 4 μs and bipolar mode). The effect of the combined treatments was studied by surface response methodology, with AS-48 concentration and HIPEF treatment time as process variables. A bacteriocin concentration of 0.613 AU/ml in combination with HIPEF treatment time of 1,000 μs reduced the population of pediococci by 6.6 log cycles in apple juice and yielded an apple juice that was free from pediococci during a 30-day storage period at 4 and 22°C. In contrast, application of HIPEF treatment alone had no effect on the surviving pediococci during storage of juice at 22°C. The combined treatment significantly improved the stability of the juice against spoilage by exopolysaccharide-producing P. parvulus.

Inactivation of Polyphenoloxidase of Pear by Pulsed Electric Fields

2010 ◽  
Vol 6 (3) ◽  
Author(s):  
Wei Zhao ◽  
Ruijin Yang ◽  
Xiao Hua ◽  
Wenbin Zhang ◽  
Yali Tang ◽  
...  
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Electric Fields ◽  
Treatment Time ◽  
Pulsed Electric Fields ◽  
Polynomial Equation ◽  
Suitable Model ◽  
First Order ◽  
Order Polynomial

Pulsed electric fields (PEF) were utilized for inhibition of polyphenoloxidase (PPO) of pear. The effects of PEF electric field strength, treatment time and the temperature on the reduction of PPO activity were evaluated in this study. A maximum of 95.5% inactivation of pear PPO was observed with the PEF treatment at 35 kV/cm for 1200 ?s at 40°C. The classical first-order inactivation as well as modified Hülsheger’s kinetic model adequately described the enzymatic inhibition in PEF processing. The second-order polynomial equation was a suitable model to analyze the inactivation of PPO using PEF technology since the PEF parameters such as PEF electric field strength, treatment time and temperature could be involved in this model.

Inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in Orange and Tomato Juice Using Ohmic Heating

2011 ◽  
Vol 74 (6) ◽  
pp. 899-904 ◽  
Author(s):  
HUN-GU SAGONG ◽  
SANG-HYUN PARK ◽  
YOUNG-JIN CHOI ◽  
SANGRYEOL RYU ◽  
DONG-HYUN KANG
Keyword(s):  
Escherichia Coli ◽  
Field Strength ◽  
Electric Field ◽  
Salmonella Typhimurium ◽  
Electric Field Strength ◽  
Treatment Time ◽  
Ohmic Heating ◽  
Tomato Juice ◽  
Escherichia Coli O157 ◽  
E Coli

The effects of ohmic heating on reduction of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in orange and tomato juice were investigated. Orange and tomato juice inoculated with E. coli O157:H7, Salmonella Typhimurium, and L. monocytogenes were subjected to ohmic heating with selected parameters including electric field strength from 10 to 20 V/cm and treatment times from 0 to 540 s. The number of pathogens was reduced by increasing the electric field strength from 10 to 20 V/cm as well as increasing treatment time. The population of E. coli O157:H7 was reduced more than 5 log after 120, 210, and 540 s of treatment in orange juice with 20, 15, and 10 V/cm electric field strengths, respectively. In tomato juice, levels of E. coli O157:H7 were reduced more than 5 log after 90, 180, and 480 s with the same electric field strengths. Similar phenomena were observed for Salmonella Typhimurium and L. monocytogenes, but E. coli O157:H7 was the most resistant to ohmic heating treatment. These results show that ohmic heating is potentially useful for inactivation of E. coli O157:H7, Salmonella Typhimurium, and L. monocytogenes and that the effect of inactivation depends on applied electric field strength, treatment time, pathogen species, and type of juice.

Effects of Pulsed Electric Field Processing and Storage on the Quality and Stability of Single-Strength Orange Juice

2002 ◽  
Vol 65 (10) ◽  
pp. 1623-1627 ◽  
Author(s):  
Z. AYHAN ◽  
Q. H. ZHANG ◽  
D. B. MIN
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Orange Juice ◽  
Sensory Quality ◽  
Pulsed Electric Field ◽  
Ethyl Butyrate ◽  
Processing And Storage ◽  
And Storage

The effects of pulsed electric field (PEF) processing on microorganisms in orange juice and on the flavor and color of the juice during storage for 112 days at 4 and 22°C were investigated. Single-strength orange juice was PEF processed at an electric field strength of 35 kV/cm for 59 μs and placed into sterilized glass bottles in a sanitary glove box. PEF-processed orange juice was microbiologically stable at 4 and 22°C for 112 days. PEF processing resulted in significant increases in the hydrocarbons d-limonene, α-pinene, myrecene, and valencene (P ≤ 0.05) but did not have any effect on octanal, decanal, ethyl butyrate, and linalool. The levels of hydrocarbon compounds did not change at 4 and 22°C in 112 days. Octanal, decanal, ethyl butyrate, and linalool levels significantly decreased in 14 days at 4°C and in 2 days at 22°C. The decrease in these compounds did not have a significant effect on the sensory quality of the orange juice (P ≥ 0.05). The microorganisms in PEF-processed orange juice, along with the flavor and color of the juice, remained stable at 4°C for 112 days.

Effect of Pulsed Electric Field on Freeze-Drying of Potato Tissue

2014 ◽  
Vol 10 (4) ◽  
pp. 857-862 ◽  
Author(s):  
Yali Wu ◽  
Dongguang Zhang
Keyword(s):  
Energy Consumption ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Pulse Width ◽  
Unit Area ◽  
Pulsed Electric Field ◽  
Pulse Number ◽  
Drying Rate ◽  
Drying Time

Abstract The influence of pulsed electric field (PEF) on the drying behavior of potato was investigated, and the optimal parameters were determined. Drying experiments were conducted with different PEF pre-treatments. The effects of process parameters of PEF pre-treatment were examined with respect to drying rate, drying time, productivity per unit area, and energy consumption. Results showed that the three parameters investigated were significant in the following sequence: pulse number, electric field strength, and pulse width. The optimal electric field strength, pulse width, and pulse number were 1,500 V cm−1, 120 μs, and 45 pulses, respectively. Under these optimal conditions, productivity per unit area increased by 32.28%, specific energy consumption decreased by 16.59%, drying time was shortened by 31.47%, and drying rate improved by 14.31% compared with the control group.

Effective Modes of Pre-Sowing Treatment of Sunfl ower Seeds in an Electric Field of Alternating Voltage

2021 ◽  
Vol 2 (43) ◽  
pp. 3-8
Author(s):  
Igor V. Yudaev ◽  
◽  
Sergey V. Volobuev ◽  
Yuriy I. Khanin ◽  
Denis S. Ivushkin
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Treatment Time ◽  
Negative Impact ◽  
Raw Material ◽  
Research Purpose ◽  
Oilseed Crop ◽  
Processing Modes ◽  
Alternating Voltage

Sunflower is the main oilseed crop in Russia and serves as a raw material for the production of vegetable oil. In order to increase field germination, plant safety, increase the yield and oil content of seeds, chemical and biological preparations are used that are not completely absorbed by plants and remain in the soil, where they accumulate and have a negative impact on the environment. To increase the conditioned qualities of seeds, electrophysical methods of their pre-sowing treatment are used, which accelerate the processes of germination in the seed and suppress the pathogenic microflora. Depending on the morphological features of the seed structure, it is necessary to set the processing modes for each culture, in which the greatest technological effect is achieved. (Research purpose) The research purpose is in studying the effect of the electric field of alternating voltage of industrial frequency 50 Hertz on the laboratory germination of sunflower hybrid seeds and searching for effective treatment modes. (Materials and methods) The SKAT-70 device was used as a source of high alternating voltage, the seeds were placed in a chamber between the electrodes, which, after processing, were placed in Petri dishes and germinated in a thermostat. (Results and discussion) The electric field strength in the experiments varied from 2 to 10 kilovolts per centimeter, in increments of 2 kilovolts per centimeter, and the seed treatment time from 15 to 105 seconds with an interval of 15 seconds. At a voltage of 2 kilovolts per centimeter, laboratory germination increased slightly, the maximum values were achieved at a voltage of 6-8 kilovolts per centimeter and the exposure time was from 60 to 90 seconds. (Conclusions) Effective processing modes are processing during 90 seconds at an electric field strength of 6 kilovolts per centimeter, and processing during 60 seconds at a voltage of 8 kilovolts per centimeter.

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