Browsing by Author "Aranguiz, V"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Effects of blanching and calcium infiltration on PPO activity, texture, microstructure and kinetics of osmotic dehydration of apple tissue
    (ELSEVIER SCIENCE BV, 1998) del Valle, JM; Aranguiz, V; Leon, H
    HTST blanching of apple pieces caused PPO inactivation and sample softening. PPO inactivation was minimal during immersion in water at 40 degrees C, but it increased with temperature after 15 min exposure at 55 to 65 degrees C. Associated softening decreased when adding 0.6% CaCl2 to the blanching medium. Samples blanched at 40 degrees C were softer than those heated at 55 degrees C in calcium solution, thus suggesting PME activation after 15 min at 55 degrees C. Vacuum infiltration of apple pieces caused cellular damage that increased as the applied pressure increased from 59.9 to 9.3 kPa, and was unaffected by the speed of restoration of ambient pressure. Texture improved when using aqueous CaCl2 solutions instead of distilled water, but no positive effect was observed for HTST blanched apples by vacuum infiltration of calcium. As a result of osmotic dehydration (OD) with aqueous sucrose solutions apple pieces lost water and texture and gained sucrose. HTST-blanched apple pieces suffered extensive material losses during OD and had poor final textures. Untreated apples and samples treated with 0.6% CaCl2 at 40 degrees C (Ih) behaved similarly. Samples treated with 0.6% CaCl2 at 55 degrees C (15 min) and vacuum (9.3 kPa) infiltrated with 2% CaCl2 had the largest sucrose gains and best final textures. Improved texture was generally associated with improved maintenance of sample microstructure. (C) 1999 Published by Elsevier Science Ltd on behalf of the Canadian Institute of Food Science and Technology. All rights reserved.
  • Thumbnail Image
    Item
    Volumetric procedure to assess infiltration kinetics and porosity of fruits by applying a vacuum pulse
    (ELSEVIER SCI LTD, 1998) del Valle, JM; Aranguiz, V; Diaz, L
    In this work an improved 'volumetric' procedure was developed to assess fruit porosity using a hydrodynamic mechanism, to replace the 'gravimetric' alternative proposed by Fito in 1994 This procedure also facilitated study of the kinetics of liquid infiltration in fruit pieces as a result of the application of a vacuum pulse. It was observed that apparent porosity increased as the absolute pressure of the vacuum pulse decreased, probably as a result of tissue damage or deformation-relaxation phenomena. In the case of apples, porosity increased from an initial value of about 0.20 to about 0.30, and this increase took place in a relatively short period (about 1 min after vacuum rupture). These values did not appear to be significantly (P < 0.01) affected by either apple variety (Granny Smith or Starking Delicious) or sucrose concentration (0 or 16% w/w) in the infiltrated solution, but increased during ambient storage. Porosity values for bananas and peaches are also reported. (C) 1998 Elsevier Science Limited. All rights reserved.