title: Nonthermal inactivation and sublethal injury of Lactobacillus plantarum in apple cider by a pilot plant scale continuous supercritical carbon dioxide system.
abstract: The objective of this study was to evaluate the efficacy of supercritical carbon dioxide (SCCO(2)) for inactivating Lactobacillus plantarum in apple cider using a continuous system with a gas-liquid metal contactor. Pasteurized apple cider without preservatives was inoculated with L. plantarum and processed using a SCCO(2) system at a CO(2) concentration range of 0-12% (g CO(2)/100g product), outlet temperatures of 34, 38, and 42 °C, a system pressure of 7.6 MPa, and a flow rate of 1 L/min. Processing with SCCO(2) significantly (P<0.05) enhanced inactivation of L. plantarum in apple cider, resulting in a 5 log reduction with 8% CO(2) at 42 °C. The response surface model indicated that both CO(2) concentration and temperature contributed to the microbial inactivation. The extent of sublethal injury in surviving cells in processed apple cider increased as CO(2) concentration and processing temperature increased, however the percent injury dramatically decreased during SCCO(2) processing at 42 °C. Structural damage in cell membranes after SCCO(2) processing was observed by SEM. Refrigeration (4 °C) after SCCO(2) processing effectively inhibited the re-growth of surviving L. plantarum during storage for 28 days. Thus this study suggests that SCCO(2) processing is effective in eliminating L. plantarum and could be applicable for nonthermal pasteurization of apple cider.
authors.affiliation: Food Science and Technology Programme, Department of Chemistry, National University of Singapore, Block S3, Level 6, Science Drive 4, Singapore 117543, Republic of Singapore.
authors.forename: Hyun-Gyun
authors.initials: HG
authors.lastname: Yuk
authors.forename: David J
authors.initials: DJ
authors.lastname: Geveke
mesh_terms: D001628:Beverages / Q000382:microbiology*; D002245:Carbon Dioxide / Q000494:pharmacology*; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004305:Dose-Response Relationship, Drug; D005506:Food Contamination / Q000032:analysis / Q000517:prevention & control; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods*; D006801:Humans; D048191:Lactiplantibacillus plantarum / Q000187:drug effects* / Q000254:growth & development; D027845:Malus / Q000382:microbiology; D013696:Temperature
chemical_list: D002245:Carbon Dioxide