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Indexed by:Journal Papers

Date of Publication:2015-06-01

Journal:AICHE JOURNAL

Included Journals:SCIE、EI、Scopus

Volume:61

Issue:6

Page Number:2048-2057

ISSN No.:0001-1541

Key Words:freeze-drying; liquid material; unsaturated; initial saturation; prebuilt pore

Abstract:To save drying time and increase productivity, a novel idea was proposed for freeze-drying of liquid materials by creating an initially unsaturated frozen structure. An experimental investigation was carried out aiming at verifying the idea using a multifunctional freeze-drying apparatus. Mannitol was selected as the primary solute in aqueous solution. Liquid nitrogen ice-cream making method was used to prepare the frozen materials with different initial porosities. Results show that freeze-drying can be significantly enhanced with the initially unsaturated frozen material, and substantial drying time can be saved compared with conventional freeze-drying of the initially saturated one. Drying time was found to decrease with the decrease in the initial saturation. The drying time for the initially unsaturated frozen sample (S-0=0.28 or 0.69 of initial porosity) can be at best 32% shorter than that required for the saturated one (S-0=1.00 or zero porosity). This unique technique is easy to implement and improves the freeze-drying performance of liquid materials. (c) 2015 American Institute of Chemical Engineers AIChE J, 61: 2048-2057, 2015