Modeling High-Intensity Pulsed Electric Field Inactivation of a Lipase from Pseudomonas fluorescens

Experimental values (A) and response surface plot (B) relating residual lipase activity (RA) in a simulated skim milk ultra-filtrate to different high-intensity pulsed electric field conditions. Experimental data are shown as the mean±standard deviation.

Effect of electric field strength on the rate constant (k) estimated by a simple first-order model used to describe the high-intensity pulsed electric field–inactivation of a lipase from Pseudomonas fluorescens in a simulated skim milk ultrafiltrate. Results are expressed as the mean±standard deviation.

Effect of electric field strength on the rate constants (k, RA_∞) estimated by a first-order fractional conversion model used to describe the high-intensity pulsed electric field–inactivation of a lipase from Pseudomonas fluorescens in a simulated skim milk ultrafiltrate. Results are expressed as the mean±standard deviation.

Effect of electric field strength on the rate constants (α, γ) estimated by a Weibull model used to describe the high-intensity pulsed electric field–inactivation of a lipase from Pseudomonas fluorescens in a simulated skim milk ultrafiltrate. Results are expressed as the mean±standard deviation.

Lipase inactivation in a high-intensity pulsed electric field–treated simulated skim milk ultrafiltrate solution as modeled by simple first-order, fractional conversion, and Weibull kinetics. Plotted lines correspond to the values obtained from the estimated equations (see Equations 15, 16, and 19 in text). Diamonds, squares, triangles, and circles correspond to experimental residual activity (RA) found after 16.37-, 18.52-, 22.67-, and 27.42-kV/cm treatments, respectively.

Experimental values of residual lipase activity (RA) expressed as a function of the electric energy density (Q) supplied under different high-intensity pulsed electric field treatment conditions. The plotted line corresponds to the adjustment of the Weibull function to the observed data (see Equation 20 in text).