Inactivation of Microorganisms by Electrohydraulic Shock1

Gilliland, S. E.; Speck, M. L.

doi:10.1128/aem.15.5.1031-1037.1967

Cited by 55 publications

(18 citation statements)

References 11 publications

(9 reference statements)

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“…The present study showed that similar inactivation of native biota in whole raw milk can be achieved by H ⁄ PEF compared to conventional pasteurization, but the H ⁄ PEF hurdle approach proved to be slightly more effective in UHT milk. These findings are in agreement with the results of other researchers who suggested that the apparently greater stability of micro-organisms in raw vs UHT milk could be due to the altered physicochemical properties in the latter, as well as the presence of more fat and proteins (Gilliland and Speck 1967;Martín et al 1996). However, a study by Picart et al (2002) carried out with dairy cream did not confirm the protective effect of higher fat content towards micro-organisms exposed to PEF, which might indicate that there could be an 'optimal' fat level below that of cream providing maximum protection to the micro-organism.…”

Section: Storage Time (Days)supporting

confidence: 93%

Antimicrobial effect and shelf-life extension by combined thermal and pulsed electric field treatment of milk

Walkling-Ribeiro

Noci

Cronin

et al. 2009

Journal of Applied Microbiology

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Aims: The impact of a combined hurdle treatment of heat and pulsed electric fields (PEF) was studied on native microbiota used for the inoculation of low‐fat ultra‐high temperature (UHT) milk and whole raw milk. Microbiological shelf‐life of the latter following hurdle treatment or thermal pasteurization was also investigated. Methods and Results: UHT milk was preheated to 30°C, 40°C or 50°C over a 60‐s period, pulsed for 50 μs or 60 μs at a field strength of 40 kV cm−1 or for 33 μs at 50 kV cm−1. Heat and PEF reduced the microbial count by a maximum of 6·4 log in UHT milk (50°C; 50 kV cm−1, 33 μs) compared to 6·0 log (P ≥ 0·05) obtained by thermal pasteurization (26 s, 72°C). When raw milk was treated with a combination of hurdles (50°C; 40 kV cm−1, 60 μs) a 6·0 log inactivation of microbiota was achieved and microbiological milk shelf‐life was extended to 21 days under refrigeration (4°C) vs 14 days in thermally pasteurized milk. Native microbiota was decreased by 6·7 log following conventional pasteurization. Conclusions: The findings suggest that heat and PEF achieved similar inactivation of native microbiota in milk and longer stabilization of microbiological shelf‐life than thermal pasteurization. Significance and Impact of the Study: A hurdle approach of heat and PEF could represent a valid milk processing alternative to conventional pasteurization. Hurdle treatment might also preserve native milk quality better due to less thermal exposure.

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Section: Storage Time (Days)supporting

confidence: 93%

Antimicrobial effect and shelf-life extension by combined thermal and pulsed electric field treatment of milk

Walkling-Ribeiro

Noci

Cronin

et al. 2009

Journal of Applied Microbiology

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“…(1992) It is more difficult to reduce the number of microorganisms present in skim milk than in buffer solutions and model foods because the composition of skim milk is very complex (i.e., high protein content 33-40 g/L) (Goff and Hill 1993). These substances diminish the lethal effect of PEF in microorganisms by absorbing free radicals and ions which are active in the cell breakdown (Allen and Soyke 1966;Gilliland and Speck 1967a). Moreover, the inactivation of bacteria by PEF is a function of solution resistivity, which is inversely proportional to ionic strength.…”

Section: Treatment In a Static Chamber Systemmentioning

confidence: 99%

“…On the other hand, the presence of protein in the saline solution reduced the effectiveness of treatment and increased energy was required for complete sterilization. Proteins diminish the effect because they may absorb the active radicals and ions resulting from the discharges (Allen and Soike 1966;Gilliland and Speck 1967a).…”

Section: Introductionmentioning

confidence: 99%

INACTIVATION OF ESCHERICHIA COLI IN SKIM MILK BY HIGH INTENSITY PULSED ELECTRIC FIELDS

Martín

Qin²,

Chang³

et al. 1997

J Food Process Engineering

170

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The inactivation of microorganisms is the most important function in the processing of milk and dairy products. Traditionally, this purpose is realized by thermal treatment, but heat produces alterations to flavor and taste in addition to nutrient loss. The high intensity pulsed electric field (PEF) treatment should be a good alternative to heat because demonstrations have shown PEF can reduce the Escherichia coli survival fraction in aqueous solutions and model foods. In this study, PEF treatment was found to inactivate E. coli in skim milk (inoculum 109 CFU/mL) at 15C. The microorganism inactivation satisfied Hülsheger's model following a first order kinetic for both the electric field intensity and number of pulses when skim milk inoculated with E. coli was treated in a static or continuous flow chamber. PEF treatment in a continuous system when the critical electric field (Ec) and minimum number of pulses (nmin) were 12.34 kV/cm and 2.7 at 30 kV/cm and 30 pulses (0.7–1.8 μs pulse width) inactivated more microorganisms than in a static system. It has also been proven that increasing the pulse duration increases the E. coli inactivation. The inactivation of E. coli using PEF is more limited in skim milk than in a buffer solution when exposed to similar treatment conditions of field intensity and number of pulses due to the complex composition of skim milk, its lower electrical resistivity and the presence of proteins.

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“…On the other hand, the presence of proteins and fats in liquid egg (Table 6), both important nutrients for microbial growth (Banwart 1989), add some constraints to the effectiveness of the PEF treatment. Fats exhibit a protective role for microorganisms and proteins diminish the effectiveness of PEF treatment because they may absorb the active radicals and ions resulting from the discharges (Allen and Soike 1966;Gilliland and Speck 1967).…”

Section: Fig 5 E Cow In Liquid Egg After Pef Treatment At 26 Kv/cmmentioning

confidence: 99%

Inactivation of Escherichia Coli Suspended in Liquid Egg Using Pulsed Electric Fields

Martı́n-Belloso

Vega-Mercado²,

Qin³

et al. 1997

J Food Processing Preservation

124

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Liquid egg inoculated with Escherichia coli was exposed to a 26kV/cm pulsed electric field with 2 and 4 μs pulse duration, 1.25 and 2.50 Hz pulsing rates, up to 100 pulses/unit volume, and stepwise and continuous recirculation treatment schemes while maintaining a bulk temperature below 37C. The inactivation of E. coli was a function of the pulse duration and the number of pulses. The destruction of Escherichia coli in liquid egg followed a first order kinetic and the treatment was more effective when the applied pulses were of a 4 μs pulse duration. A 6D reduction was obtained for viable E. coli using both pulsing rates and treatment schemes with no protein coagulation.

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Inactivation of Microorganisms by Electrohydraulic Shock1

Cited by 55 publications

References 11 publications

Antimicrobial effect and shelf-life extension by combined thermal and pulsed electric field treatment of milk

Antimicrobial effect and shelf-life extension by combined thermal and pulsed electric field treatment of milk

INACTIVATION OF ESCHERICHIA COLI IN SKIM MILK BY HIGH INTENSITY PULSED ELECTRIC FIELDS

Inactivation of Escherichia Coli Suspended in Liquid Egg Using Pulsed Electric Fields

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