Osmotic Dehydration of Apple Cylinders: I. Conventional Batch Processing Conditions

Abstract

Osmotic drying was carried out, with cylindrical samples of apple cut to a diameter-to-length ratio of 1:1, in a well-agitated large tank containing the osmotic solution at the desired temperature. The solution-to-fruit volume ratio was kept greater than 30. A modified central composite rotatable design (CCRD) was used with five levels of sucrose concentrations (34–63°Brix) and five temperatures (34–66°C). Kinetic parameters weight reduction (WR), moisture loss (ML), solids gain (SG) were considered. A polynomial regression model was developed to relate moisture loss and solids gain to process variables. A conventional diffusion model involving a finite cylinder was also used for moisture loss and solids gain, and the associated diffusion coefficients were computed. The calculated moisture diffusivity ranged from 8.20 × 10⁻¹⁰ to 24.26 × 10⁻¹⁰ m²/s and the solute diffusivity ranged from 7.82 × 10⁻¹⁰ to 37.24 × 10⁻¹⁰ m²/s. Suitable ranges of main parameters were identified for OD kinetics further study.

Keywords:

• Osmotic dehydration
• Effect
• Apple cylinders
• Mass transfer
• ML/SG ratio

ACKNOWLEDGEMENTS

This research was supported from a Grant from the Natural Sciences and Engineering Research Council (NSERC) of Canada.

Notes

P < 0.05 significant.

P > 0.05 not significant.

P < 0.05 significant.

P > 0.05 not significant.