Structural behavior of pineapple pieces by the mass transference due to vacuum impregnation and osmotic dehydration

Abstract

Vacuum impregnation (VI) and osmotic dehydration (OD) of the pineapple (var. Red Spanish) were carried out with sucrose solution. This variety showed a low porosity either real (2% v) or effective (4% v) due to the presence of small intracellular spaces, which were filled of native liquid rather than air. During VI there was an exchange of native liquid by a similar volume of solution (approximately 6% of the initial volume of the fruit) and it was confirmed by scanning electronic cryomicroscopy. The fruit also suffered an increase of volume (2%) during vacuum application and it did not recover its initial volume when the atmospheric pressure was restored VI may be effective to induce rapidly compositional changes in the pineapple, allowing the introduction of functional ingredients, at the same time it may accelerate the mass transference in OD. The latter was also confirmed by microscopy in the samples of OD at pulsing vacuum, where there was a higher advance of impregnation (perturbation front) than in samples of OD at atmospheric pressure.