Optimization of effective high hydrostatic pressure treatment of Bacillus subtilis in Hami melon juice

• We isolated and identified the dominant microorganism from fresh Hami-melon juice.
• The Bacillus subtilis was the dominant microbiology in Hami melon juice.
• Optimum process parameters were obtained, pressure, 464 MPa, temperature, 54.61 °C, and pressure holding time, 12.8 min.

In this study, we investigated whether high hydrostatic pressure processing (HPP) reduced the isolation of Bacillus subtilis   from fresh Hami melon juice. The parameters were as follows: pressure = 300–500 MPa, moderate heat = 45–65 °C, and pressure-holding time = 10–20 min. In the present study, we employed the response surface methodology and a quadratic equation of HPP inactivation was constructed. By analyzing the response surface plots and the corresponding contour plots, and by solving the quadratic equation, the experimental values were shown to be in significantly good agreement with the predicted values because the adjusted coefficient of determination (RAdj2) was 0.9425. The optimum process parameters for a five-log reduction of B. subtilis spores were: pressure = 464 MPa, temperature = 54.61 °C, and pressure-holding time = 12.8 min. The adequacy of the model equation for predicting the optimum response values was verified effectively using the experimental test data.