High hydrostatic pressure inactivation and recovery study of Listeria innocua and Saccharomyces cerevisiae in pitaya (Stenocereus pruinosus) juice

The high hydrostatic pressure (HHP) inactivation of Listeria innocua and Saccharomyces cerevisiae was investigated in pitaya juice subsequently stored 15 d under refrigeration to assess recovery. Juice inoculated to 7.6 +/- 0.4 or 7.3 +/- 0.3 log(10) (CFU mL(-1)) of L. innocua or S. cerevisiae, respectively, was treated at 400 to 600 MPa for 7.6 to 15 min (T-initial = 19.5 +/- 2.8 degrees C and T-max = 34.6 +/- 2.0 degrees C) following a Response Surface Design. Come-up time (CUT), defined as pressure release 1 s after reaching pressure set-point, was also evaluated. After a 400 MPa CUT treatment, no viable S. cerevisiae survivors were observed. Treatments at 550 and 600 MPa for 16 and 12 min, respectively, achieved L. innocua reductions exceeding 5-log(10). No viable S. cerevisiae were observed when treated juice was stored at 4 +/- 1 degrees C for up to 15 d. HHP appears a viable nonthermal alternative to produce a microbiologically safe and stable pitaya juice.