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Notas:
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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 mu s of total treatment time (t) using pulses of 4 mu s width at 200 Hz frequency (f) applied in mono- and bipolar mode. Moreover, frequencies up to 450 Hz and pulse width (tau) from 1 to 10 mu s were tested. Pectin methyl esterase (PME) inhibition was greater when the E, the t, the f, the tau, 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 Hulsheger's models described with enough accuracy the orange juice PME inactivation by HIPEF as a function of the individual t (R-2 = 0.955-0.996, A(f) = 1.006-1.109), E (R-2 = 0.850-0.989, A(f) = 1.021-1.104) and the combined effect of the E and the t (R-2 = 0.880-0.915, A(f) = 1.104-1.124), respectively. Residual orange juice PME activity was well related to f (R-2 = 0.990; A(f) = 1.024), tau (R-2 = 0.947; A(f)= 1.094) or Q (R-2 = 0.914-0.933; A(f) = 1.069-1.099) by a first-order fractional conversion model
This work was supported by the Departament d'Universitats, Recerca i Societat de la Informació
of the Generalitat de Catalunya (Spain), the Ministerio de Educación y Cultura
(CICYT) (Spain) through the project ALI99-1228 and the Consejerı́a de Educación of the Comunidad Autonoma de Madrid (Spain) through the project CAM 07G/0040/2000. P. Elez-Martı́nez thanks the Universitat de Lleida (Spain) for the pre-doctoral grant. |
