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Effects of pulsed electric fields on inactivation and metabolic activity of Lactobacillus plantarum in model beer.
- Source :
-
Journal of applied microbiology [J Appl Microbiol] 2002; Vol. 93 (2), pp. 326-35. - Publication Year :
- 2002
-
Abstract
- Aims: Inactivation and sublethal injury of Lactobacillus plantarum at different pulsed electric field (PEF) strengths and total energy inputs were investigated to differentiate reversible and irreversible impacts on cell functionality.<br />Methods and Results: Lactobacillus plantarum was treated with PEF in model beer (MB) to determine critical values of field strength and energy input for cell inactivation. Below critical values, metabolic activity and membrane integrity were initially reduced without loss of viability. Above critical values, however, irreversible cell damage occurred. Presence of nisin or hop extract, during PEF treatment, resulted in an additional reduction of cell viability by 1;5 log cycles. Also, addition of the hop extract resulted in an additional two log cycles of sublethal injury. Partial reversibility of membrane damage was observed using propidium iodide (PI) uptake and staining. Inoculated MB containing hops was stored after PEF to evaluate the efficacy of such treatment for beer preservation.<br />Conclusion: Cells were inactivated only above critical values of 13 kV x cm(-1) and 64 kJ x kg(-1); below these values cell damage was reversible. Storage experiments revealed that surviving cells were killed after 15 h storage in MB containing hops.<br />Significance and Impact of the Study: Both reversible and irreversible cell damage due to PEF treatment was detected, depending on specific treatment conditions. The combination of PEF and hop addition is a promising nonthermal method of preservation for beer.
- Subjects :
- Anti-Bacterial Agents pharmacology
Cell Membrane drug effects
Cell Membrane radiation effects
Electromagnetic Fields
Food Contamination
Food Preservation
Humulus
Hydrogen-Ion Concentration
Lactobacillus drug effects
Nisin pharmacology
Beer microbiology
Lactobacillus metabolism
Lactobacillus radiation effects
Sterilization methods
Subjects
Details
- Language :
- English
- ISSN :
- 1364-5072
- Volume :
- 93
- Issue :
- 2
- Database :
- MEDLINE
- Journal :
- Journal of applied microbiology
- Publication Type :
- Academic Journal
- Accession number :
- 12147082
- Full Text :
- https://doi.org/10.1046/j.1365-2672.2002.01699.x