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.