Modeling the reduction of pectin methyl esterase activity in orange juice by high intensity pulsed electric fields Original Research Article

Orange juice was processed by high intensity pulsed electric fields (HIPEF) at different processing conditions: electric field strengths (E) from 5 to 35 kV/cm up to 1500 μs of total treatment time (t) using pulses of 4 μs width at 200 Hz frequency (f) applied in mono- and bipolar mode. Moreover, frequencies up to 450 Hz and pulse width (τ) from 1 to 10 μs were tested. Pectin methyl esterase (PME) inhibition was greater when the E, the t, the f, the τ, and the electrical energy density (Q) increased. HIPEF inactivation of orange juice PME with processing parameters was modeled. The first-order fractional conversion, Fermi’s and Hülsheger’s models described with enough accuracy the orange juice PME inactivation by HIPEF as a function of the individual t (R2 = 0.955–0.996, Af = 1.006–1.109), E (R2 = 0.850–0.989, Af = 1.021–1.104) and the combined effect of the E and the t (R2 = 0.880–0.915, Af = 1.104–1.124), respectively. Residual orange juice PME activity was well related to f (R2 = 0.990; Af = 1.024), τ (R2 = 0.947; Af = 1.094) or Q (R2 = 0.914–0.933; Af = 1.069–1.099) by a first-order fractional conversion model.