FIG. 3.

Effect of continuous pressurization and pressure pulse treatment at 70°C in THB on counts of Bacillus spores and the release of DPA from the spores. (A) B. subtilis TMW 2.485; (B) B. amyloliquefaciens Fad 82; (C) B. licheniformis TMW 2.492. ○ and ▵, spore counts; • and ▴, DPA release relative to the initial DPA content of the spores. • and ○, continuous pressurization at 800 MPa; ▴ and ▵, pressure pulse treatment, 800 MPa for 2 min followed by 0.1 MPa. The DPA contents of B. subtilis, B. amyloliquefaciens, and B. licheniformis spores were 1.45 ± 0.15, 0.96 ± 0.13, and 0.39 ± 0.05 mM/10⁹ spores, respectively. Data shown are means of at least two independent experiments. The standard deviations for the determination of spore counts and the DPA release were generally less than 0.66 log units and 5%, respectively. Lines dropping below the x axis indicate spore counts below the detection limit (log [N/N₀] = −6.4, where N and N₀ are as defined for Fig. 1).