Enhanced Mass Transfer During Osmotic Dehydration of High Pressure Treated Pineapple

High pressure pretreatment (100–700 MPa) was applied to
enhance mass transfer rates during osmotic dehydration of
pineapples and accelerate the process. Experimentally determined
diffusivity values, based on a Fickian model, increased
fourfold for water and twofold for sugar. Diffusivity
values were correlated with pretreatment pressure by an
equation of the form D�A exp(�B/P), which suggests that
diffusivity would level after an initial increase in pressure.
The increase was attributed to breaking-up of cells walls
which facilitated the transport of water. Evidence for the extent
of cell wall break-up with applied pressure was based
on differential interference contrast microscopic examination
of tissue. Preliminary experiments on rehydration characteristics
showed high pressure pretreated samples did not
absorb as much water as controls.