title: Pulsed electric field processing of different fruit juices: impact of pH and temperature on inactivation of spoilage and pathogenic micro-organisms.
abstract: Pulsed electrical field (PEF) technology can be used for the inactivation of micro-organisms and therefore for preservation of food products. It is a mild technology compared to thermal pasteurization because a lower temperature is used during processing, leading to a better retention of the quality. In this study, pathogenic and spoilage micro-organisms relevant in refrigerated fruit juices were studied to determine the impact of process parameters and juice composition on the effectiveness of the PEF process to inactivate the micro-organisms. Experiments were performed using a continuous-flow PEF system at an electrical field strength of 20 kV/cm with variable frequencies to evaluate the inactivation of Salmonella Panama, Escherichia coli, Listeria monocytogenes and Saccharomyces cerevisiae in apple, orange and watermelon juices. Kinetic data showed that under the same conditions, S. cerevisiae was the most sensitive micro-organism, followed by S. Panama and E. coli, which displayed comparable inactivation kinetics. L. monocytogenes was the most resistant micro-organism towards the treatment conditions tested. A synergistic effect between temperature and electric pulses was observed at inlet temperatures above 35 °C, hence less energy for inactivation was required at higher temperatures. Different juice matrices resulted in a different degree of inactivation, predominantly determined by pH. The survival curves were nonlinear and could satisfactorily be modeled with the Weibull model.
authors.affiliation: Wageningen UR Food & Biobased Research, P.O. Box 17, 6700 AA Wageningen, The Netherlands. Electronic address: rian.timmermans@wur.nl.
authors.forename: R A H
authors.initials: RA
authors.lastname: Timmermans
authors.affiliation: Wageningen UR Food & Biobased Research, P.O. Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: M N
authors.initials: MN
authors.lastname: Nierop Groot
authors.affiliation: Wageningen UR Food & Biobased Research, P.O. Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: A L
authors.initials: AL
authors.lastname: Nederhoff
authors.affiliation: Food Quality & Design Group, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands.
authors.forename: M A J S
authors.initials: MA
authors.lastname: van Boekel
authors.affiliation: Wageningen UR Food & Biobased Research, P.O. Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: A M
authors.initials: AM
authors.lastname: Matser
authors.affiliation: Wageningen UR Food & Biobased Research, P.O. Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: H C
authors.initials: HC
authors.lastname: Mastwijk
mesh_terms: D001419:Bacteria / Q000254:growth & development; D018407:Bacterial Physiological Phenomena; D001628:Beverages / Q000382:microbiology*; D004926:Escherichia coli / Q000254:growth & development / Q000502:physiology; D005638:Fruit / Q000382:microbiology; D006863:Hydrogen-Ion Concentration; D008089:Listeria monocytogenes / Q000254:growth & development / Q000502:physiology; D008954:Models, Biological; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology*; D012475:Salmonella / Q000254:growth & development / Q000502:physiology; D016019:Survival Analysis; D013696:Temperature
keywords: Fruit juice; Inactivation kinetics; Pulsed electric field (PEF); Weibull