title: Synergistic effects of high hydrostatic pressure, mild heating, and amino acids on germination and inactivation of Clostridium sporogenes spores.
abstract: The synergistic effects of high hydrostatic pressure (HHP), mild heating, and amino acids on the germination of Clostridium sporogenes spores were examined by determining the number of surviving spores that returned to vegetative growth after pasteurization following these treatments. Pressurization at 200 MPa at a temperature higher than 40°C and treatment with some of the 19 l-amino acids at 10 mM or higher synergistically facilitated germination. When one of these factors was omitted, the level of germination was insignificant. Pressures of 100 and 400 MPa were less effective than 200 MPa. The spores were effectively inactivated by between 1.8 and 4.8 logs by pasteurization at 80°C after pressurization at 200 MPa at 45°C for 120 min with one of the amino acids with moderate hydrophobicity, such as Leu, Phe, Cys Met, Ala, Gly, or Ser. However, other amino acids showed poor inactivation effects of less than 0.9 logs. Spores in solutions containing 80 mM of either Leu, Phe, Cys, Met, Ala, Gly, or Ser were successfully inactivated by pasteurization by more than 5.4 logs after pressurization at 200 MPa at 70°C for 15 to 120 min. Ala and Met reduced the spore viability by 2.8 and 1.8 logs, respectively, by pasteurization at a concentration of 1 mM under 200 MPa at 70°C. These results indicate that germination of the spores is facilitated by a combination of high hydrostatic pressure, mild heating, and amino acids.
authors.affiliation: Department of Food Sciences, Niigata University of Pharmacy and Applied Life Sciences, Higashijima, Akiha-ku, Niigata, Japan.
authors.forename: Takateru
authors.initials: T
authors.lastname: Ishimori
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Takahashi
authors.forename: Masato
authors.initials: M
authors.lastname: Goto
authors.forename: Suguru
authors.initials: S
authors.lastname: Nakagawa
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Kasai
authors.forename: Yukifumi
authors.initials: Y
authors.lastname: Konagaya
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Batori
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kobayashi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Urakami
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D003013:Clostridium / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology / Q000528:radiation effects*; D006361:Heating; D006874:Hydrostatic Pressure; D050296:Microbial Viability / Q000187:drug effects* / Q000528:radiation effects*; D061352:Pasteurization / Q000379:methods*; D013171:Spores, Bacterial / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology / Q000528:radiation effects*
chemical_list: D000596:Amino Acids