title: Pasteurization of fruit juices of different pH values by combined high hydrostatic pressure and carbon dioxide.
abstract: The inactivation of the selected vegetative bacteria Escherichia coli, Listeria innocua, and Lactobacillus plantarum by high hydrostatic pressure (HHP) in physiological saline (PS) and in four fruit juices with pHs ranging from 3.4 to 6.3, with or without dissolved CO(2),  was investigated. The inactivation effect of HHP on the bacteria was greatly enhanced by dissolved CO(2). Effective inactivation (>7 log) was achieved at 250 MPa for E. coli and 350 MPa for L. innocua and L. plantarum in the presence of 0.2 M CO(2)  at room temperature for 15 min in PS, with additional inactivation of more than 4 log for all three bacteria species compared with the results with HHP treatment alone. The combined inactivation by HHP and CO(2) in tomato juice of pH 4.2 and carrot juice of pH 6.3 showed minor differences  compared with that in PS. By comparison, the combined effect in orange juice of pH 3.8 was considerably promoted, while the HHP inactivation was enhanced only to a limited extent. In another orange juice with a pH of 3.4, all three strains lost their pressure resistance. HHP alone completely  inactivated E. coli at relatively mild pressures of 200 MPa and L. innocua and L. plantarum at 300 MPa. Observations of the survival of the bacteria in treated juices also showed that the combined treatment caused more sublethal injury, which increased further inactivation  at a relatively mild pH of 4.2 during storage. The results indicated that the combined treatment of HHP with dissolved CO(2) may provide an effective method for the preservation of low- or medium-acid fruit and vegetable juices at relatively low pressures. HHP alone inactivated bacteria  effectively in high-acid fruit juice.
authors.affiliation: Engineering Research Centre of Bio-Process, Ministry of Education of China, School of Chemical Engineering, Hefei University of Technology, 193 Tun Xi Road, Hefei, Anhui 230009, People's Republic of China 2901862.
authors.forename: Wang
authors.initials: W
authors.lastname: Li
authors.forename: Jian
authors.initials: J
authors.lastname: Pan
authors.forename: Huiming
authors.initials: H
authors.lastname: Xie
authors.forename: Yi
authors.initials: Y
authors.lastname: Yang
authors.forename: Dianfei
authors.initials: D
authors.lastname: Zhou
authors.forename: Zhaona
authors.initials: Z
authors.lastname: Zhu
mesh_terms: D001628:Beverages / Q000382:microbiology*; D002245:Carbon Dioxide / Q000494:pharmacology*; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D005506:Food Contamination / Q000032:analysis / Q000517:prevention & control; D005519:Food Preservation / Q000379:methods*; D005638:Fruit / Q000382:microbiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006874:Hydrostatic Pressure; D048191:Lactiplantibacillus plantarum / Q000187:drug effects / Q000254:growth & development; D008087:Listeria / Q000187:drug effects / Q000254:growth & development; D050296:Microbial Viability
chemical_list: D002245:Carbon Dioxide