The Response of Some Properties of Fruits to Vacuum Impregnation

Abstract

The behavior of several fruits (three varieties of apples, strawberry, kiwi‐fruit, mango and peach) during vacuum impregnation (VI) treatments was studied by using specially designed equipment and methodology to determine deformation and impregnation levels in fruit samples. The coupling of the Hydrodynamic Mechanism (HDM) and the Deformation‐Relaxation Phenomena (DRP) was analyzed throughout the two typical steps of VI process (first period at vacuum pressure and second period at atmospheric pressure). VI experiments were carried out over different lengths of time under vacuum (t1) and at atmospheric pressure (t2) duration in order to obtain kinetic information on the coupled HDM and DRP. Nevertheless, neither the duration of t1 or t2 was observed to have an influence on the deformation and impregnation levels in the examined time scales. The effective porosities (ɛe) of the fruits that were studied were determined and compared with the fruit porosity (ɛ) obtained from density data. In almost all cases the ratio ɛe/ɛ was lower than 1, which indicates that only a fraction of fruit pores was available to HDM action. DRP affects the volume fraction of impregnated liquid in all cases.

Zinc enrichment of whole potato tuber by vacuum impregnation

“…As mentioned previously, Salvatori et al (1998) reported that in plant tissue samples of about 2 cm in characteristic dimension, with the relatively large intercellular spaces and elastic cellular arrangement, the necessary lengths of vacuum time and restoration time are within 5 min. Nevertheless, in big pieces with small pores, much more time could be necessary to complete sample equilibration in mechanical terms because of difficulties for gas release.…”

“…Gras et al (2003) used a vacuum pressure of 5 kPa for 10 min, and a 10-min restoration time for impregnation of isotonic solutions of sucrose and calcium lactate mixtures for eggplants, carrots and oyster mushroom. Salvatori et al (1998) reported that in plant tissue samples of about 2 cm in diameter, with relatively large intercellular spaces and elastic cellular arrangement, the necessary length of vacuum period in VI operations is on the order of 5 min and impregnation times with sugar syrups are on the order of the time required to achieve a stationary pressure in the tank after the valve is opened to restore atmospheric pressure.…”

Effects of Freezing Conditions on Enzyme Impregnation into Food Materials by Freeze-Thaw Infusion

“…Therefore, porous materials are suitable for VI (Salvatori et al, 1998). On the other hand, FI can be applied to various kinds of materials regardless of its porosity.…”

Microstructural changes of frozen strawberries submitted to pre-treatments with additives and vacuum impregnation

“…The flow of water and soluble solid during the vacuum impregnation implies changes in structural and transport properties (CHIRALT; FITO, 2003). The structural changes in the tissue depend on the distance in relation to the sample surface in contact with the infusion solution, according to profiles developed from the concentration (SALVATORI; ANDRÉS; CHIRALT, 1998). The thickness of the fruit in contact with the solution determines a good impregnation, because larger and thicker fruits hinder the solute entrance.…”