title: Continuous ohmic heating of commercially processed apple juice using five sequential electric fields results in rapid inactivation of Alicyclobacillus acidoterrestris spores.
abstract: Spores of Alicyclobacillus acidoterrestris, a spoilage bacterium, cause problems for the apple juice industry because they are resistant to thermal treatment. Here, we examined the sporicidal effect of an ohmic heating (OH) system with five sequential electric fields and compared it with that of conventional heating. Apple juice product (50kg) inoculated with A. acidoterrestris spores were subjected to OH (electric field strength=26.7V/cm; frequency=25kHz) at 85-100°C for 30-90s. The effect of conventional heating was also examined under these conditions. OH treatment at 100°C for 30s resulted in total inactivation of the inoculum, with no recovery of viable cells (initial population=4.8-4.9logCFU/ml), whereas 3.6-4.9logCFU/ml of the spores survived conventional heating. OH did not alter the quality (°Brix, color, and pH) of commercial apple juice (p>0.05). These results suggest that the OH system is superior to conventional heating for rapid sterilization (30s) of apple juice to assure microbiological quality in the absence of chemical additives.
authors.affiliation: Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul 02841, Republic of Korea.
authors.forename: N H
authors.initials: NH
authors.lastname: Kim
authors.affiliation: Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul 02841, Republic of Korea; Food Safety Research Institute, NONGSHIM Co., Ltd., Seoul 07057, Republic of Korea.
authors.forename: J H
authors.initials: JH
authors.lastname: Ryang
authors.affiliation: Food Safety Research Institute, NONGSHIM Co., Ltd., Seoul 07057, Republic of Korea.
authors.forename: B S
authors.initials: BS
authors.lastname: Lee
authors.affiliation: Food Safety Research Institute, NONGSHIM Co., Ltd., Seoul 07057, Republic of Korea.
authors.forename: C T
authors.initials: CT
authors.lastname: Kim
authors.affiliation: Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul 02841, Republic of Korea. Electronic address: rheems@korea.ac.kr.
authors.forename: M S
authors.initials: MS
authors.lastname: Rhee
mesh_terms: D056450:Alicyclobacillus / Q000254:growth & development*; D015169:Colony Count, Microbial; D003116:Color; D004560:Electricity; D000067030:Fruit and Vegetable Juices / Q000382:microbiology*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D027845:Malus / Q000382:microbiology*; D061352:Pasteurization / Q000379:methods*; D013171:Spores, Bacterial / Q000254:growth & development*
keywords: Alicyclobacillus acidoterrestris; Apple juice; Control; Ohmic heating; Spore