Synergistic Bactericidal Efficiency of Slightly Acidic Electrolyzed Water–High-Pressure Parallel Processing on Escherichia coli in Freshly Cut Gastrodia elata Slices

TL;DR

This study shows that combining slightly acidic water and high pressure can kill bacteria more effectively on fresh plant slices.

Contribution

The study identifies a synergistic effect between slightly acidic electrolyzed water and high-pressure treatment for bacterial control.

Findings

SAEW and high-pressure parallel processing showed a synergistic bactericidal effect on Escherichia coli.

Optimal ranges for pressure, chlorine concentration, and time were determined for maximum synergy.

Validation experiments confirmed the '1 + 1 > 2' enhancement effect within specified ranges.

Abstract

The synergistic enhancement of bactericidal efficiencies on freshly cut Gastrodia elata slices by parallel processing using slightly acidic electrolyzed water (SAEW) and high-pressure (HP) technology was comprehensively investigated in this study. To this end, appropriate experimental conditions were determined through single-factor tests, which were ACCs (available chlorine concentrations) of 30, 38, and 49 mg/L; pressures of 100, 150, and 200 MPa; treatment times of 5, 7.5, and 10 min; and material-to-liquid ratios of 1:1, 1:3, and 1:5. Under these conditions, single and parallel bactericidal tests were conducted, and the corresponding synergistic enhancement values ΔI were calculated. Subsequently, using the lethal rate of Escherichia coli (E. coli) as the response value, we fitted multiple quadratic regression equations for SAEW, HP, and SAEW–HP with respect to ACC, pressure, pressure application time, and material-to-liquid ratio. The multiple quadratic regression equation for the synergistic enhancement term ΔI was then obtained through calculation. By analyzing this equation, the synergistic enhancement range was determined. Finally, experimental points were randomly selected within the synergistic enhancement range for validation. The results demonstrate that there was a synergistic bactericidal efficiency of the SAEW–HP parallel treatment of freshly cut G. elata slices. The synergistic enhancement range was pressure (xp) ∈ [52.18, 359.58] MPa; concentration of available chlorine (xc) ∈ [28.71, 46.27] mg/L; time (xt) ∈ [2.34, 12.38] min; and the material-to-solvent ratio (xr) ∈ ø g/mL. The validation experiments confirmed that within the respective ranges of p, c, and t, the SAEW–HP parallel treatment of freshly cut G. elata slices exhibited a ‘1 + 1 > 2’ synergistic enhancement effect. These findings lay a theoretical foundation for the development of green bactericidal technologies for “adopting both minimum processing and dosage to achieve the optimal effect”.

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