Science of Scale for Freeze Drying

Tchessalov, Serguei; Luthra, Sumit; Thompson, T. N.; Graham, Lisa

doi:10.1201/9780429201400-42

Cited by 6 publications

(8 citation statements)

References 1 publication

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“…The tradeoff among product quality, throughput, and overall energy consumption is usually found based on macroscopic measurements of temperature and pressure [10][11][12][13]. Since the process is strongly influenced by the internal structure of the frozen product and local distribution of ice, solid, and voids, information on the microscale would instead be required to optimize process control [14,15].…”

Section: Introductionmentioning

confidence: 99%

Freeze-Drying with Structured Sublimation Fronts—Visualization with Neutron Imaging

et al. 2020

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The particular structure of the sublimation front in vacuum freeze-drying of porous media is, in most situations, not accessible at the pore scale. The classical measurement techniques access the process only globally. Knowledge about the structure of the front, however, is necessary for prescriptive analysis of freeze-drying, as it dictates not only drying velocity, drying time, and overall energy consumption, but also the material properties after drying. This is especially relevant in situations in which the freeze-drying process is carried out close to the collapse temperature of the product. We, therefore, study the sublimation of ice with neutron tomography and analyze the spatial formation of the dry space using the example of frozen cylindrical maltodextrin with drying parameters at the limit of material collapse. We show that the sublimation front forms unique fractal structures that differ strongly from the usual form of a flat front. Distinct dry fingers covering the sample, in addition to a fractal peripheral sublimation front, were observed. The findings are important for the understanding of freeze-drying processes and will serve as a basis for the development of microscale models of freeze-drying.

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Section: Introductionmentioning

confidence: 99%

Freeze-Drying with Structured Sublimation Fronts—Visualization with Neutron Imaging

et al. 2020

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“…The chamber pressure had little effect on the initially saturated frozen material, as shown in Figure . For such a material undergoing vial freeze‐drying, it is accepted that the vapour transportation in the porous dried layer is the major rate‐controlling factor . This uncommon phenomenon was the result of two opposite effects.…”

Section: Resultsmentioning

confidence: 83%

Freeze‐drying of ceftriaxone sodium solution frozen with prefabricated porosity

Wang¹,

Hu²,

Pan³

et al. 2018

Can J Chem Eng

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Initially unsaturated material frozen with prefabricated porosity was prepared to experimentally investigate its effect on freeze-drying of liquid material. Ceftriaxone sodium, a kind of commonly used antibiotic, was selected as the primary solute in an aqueous solution. The liquid nitrogen ice cream-making method was employed to prepare frozen materials with different initial porosities. Results showed that freeze-drying was significantly enhanced with the initially unsaturated frozen material and substantial drying time was saved compared with conventional freeze-drying. Drying time for the unsaturated sample (0.3 of saturation or 0.67 of initial porosity) was more than 20 % shorter than that required for the saturated one (1.0 of saturation without initial porosity). SEM images displayed that the dried products of the unsaturated frozen material had a pierced solid skeleton and uniform pore space with a fine and tenuous structure compared with those of the saturated one. The freezing rate exhibited little influence on the freeze-drying process. Annealing can be moderately beneficial to shortening the drying time and further improving the energy utilization. An appropriate increase in operating temperature was able to enhance the freeze-drying rate while changes in chamber pressure had a negligible effect on the process.

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“…Each of the FD and NFD processes has advantages and disadvantages. In this study, the freeze-drying method was chosen due to its essential advantages, that able to increase the stability of samples (Nail & Gatlin, 1992). Freeze-drying is an indispensable technology in formulating air materials nano-scale, hence, in the last few decades, many studies have begun to apply the technology.…”

Section: Resultsmentioning

confidence: 99%

The UV-Vis spectrum of antioxidant complex from frozen-dried egg white protein and tomato extract

Khoiriyah

Mabrur

Sumitro

et al. 2020

Berkala Penelitian Hayati

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In this study, we want to characterize egg white protein-tomato extract complex based on the UV-Vis spectrum. The formulation of antioxidant complex Non-Freeze-drying (NFD) was made at a ratio of 1:10 (v/v) while the Freeze-drying (FD) sample was made at a ratio of 1:2 (v/v). The results showed that the absorption peak of FD complex profile value was lower than the single ingredient, while the tomato extract was higher than the complex profile. On the contrary, the NFD complex showed a higher peak absorption value than to every single ingredient. Based on each UV-Vis spectrum profile, the tomato extract profile shifted the absorption peak, and the absorbance value of the FD sample was changing higher than the NFD sample, while the egg white protein spectrum profile did not change significantly in the FD and NFD samples. The absorption peak of the complex is higher than the single ingredient indicated that the characterization of the complex had been formed. In the NFD complex profile, the absorption peaks formed at the wavelength regions of 230 nm and 280 nm with absorbance values of 2.51 and 0.76 and its number has higher than those of the FD complex with absorbance values of 2.47 and 1.82 at wavelengths of 220 and 265 nm.

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Science of Scale for Freeze Drying

Cited by 6 publications

References 1 publication

Freeze-Drying with Structured Sublimation Fronts—Visualization with Neutron Imaging

Freeze-Drying with Structured Sublimation Fronts—Visualization with Neutron Imaging

Freeze‐drying of ceftriaxone sodium solution frozen with prefabricated porosity

The UV-Vis spectrum of antioxidant complex from frozen-dried egg white protein and tomato extract

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