Enhanced Mass Transfer During Osmotic Dehydration of High Pressure Treated Pineapple

Abstract

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 DϭA exp(ϪB/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.

Recent advances in drying and dehydration of fruits and vegetables: a review

“…The rate of mass transfer during OD is generally low. Techniques to improve mass transfer are partial vacuum (Rastogi and Raghava Rao 2004), ultra high hydrostatic pressure (Rastogi and Niranjan 2008), high intensity electrical fi eld pulses (Rastogi et al 1999), super critical CO 2 treatment (Tedjo et al 2002) and prior to OD processing and using centrifugal force (Azura et al 1996).…”

“…It is observed that application of high hydrostatic pressure damages the cell wall structure which leads to signifi cant changes in the tissue architecture, leaving the cells more permeable, resulting in increased mass transfer rates during OD (Rastogi and Niranjan 2008).…”

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“…The decrease in compressive force with on subjecting to high pressure may be related to the permeabilisation of cells leading to reduced mass transfer resistance thereby resulting in higher infusion. In case of pineapple slices high pressure treatment results in decrease in compressive force [26]. These results clearly indicate that the high pressure pretreatment is one of the potential methods to enhance the infusion of bioactive compounds.…”

“…The pouches were heat sealed and the samples were treated at 350 MPa for 10 min. The processing conditions were selected based on our earlier work [26]. The water was taken as a medium for transmitting pressure.…”

“…Application of high pressure treatment accelerated the diffusion of bioactive components into the solid food due to cell membranes permeabilisation resulting in decline in the resistance to infusion [24,25]. The application of high pressure pretreatment was described to increase the water and solute diffusion during osmotic dehydration of pineapples, potato, glutinous rice and turkey breast [26][27][28][29]. Sila et al, [30] demonstrated that combined effect of high pressure treatment and CaCl 2 treatment improved the texture of carrots during thermal processing.…”