Dairy Milk Particles Made with a Mono-Disperse Droplet Spray Dryer (MDDSD) Investigated for the Effect of Fat

You, Xiang; Zhou, Zihao; Liao, Zhenkai; Che, Liming; Chen, Xiao; Wu, Winston Duo; Woo, Meng Wai; Selomulya, Cordelia

doi:10.1080/07373937.2013.840650

“…The design and fabrication of particles by using spray drying has attracted much attention in recent years with a goal to improve the reproducibility and uniformity of the particles formed and the range of situations in which it can be applied. Particle size, morphology, size distribution, and degree of crystallinity have been shown to be affected by changes to the droplet processing conditions such as solvent, , temperature, − starting pH, , and inert additives to the feed solution. − …”

Section: Introductionmentioning

confidence: 99%

Drying and Crystallization of Evaporating Sodium Nitrate Aerosol Droplets

Gregson

¹

,

Robinson

²

,

Miles

³

et al. 2020

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The evaporation of liquid solution droplets and solute crystallization can be highly complex and is an important problem, particularly in spray drying where powdered products are produced from sprayed liquid droplets, such as in the food or pharmaceutical industries. In this work, we study the relationship between the evaporation rates of single levitated NaNO3 droplets under varying environmental conditions and the propensity for nucleation of NaNO3 crystals. We use a combination of an electrodynamic balance to study single-droplet evaporation kinetics, SEM imaging of dried particles, and modeling of the internal solute distribution inside a drying droplet. We show that the aqueous NaNO3 droplets exhibit broad distributions in the time that crystal nucleation is observed, droplet to droplet. The distribution of nucleation time is dependent upon environmental conditions such as the drying temperature, relative humidity (RH), and solute concentration. Even when evaporating in 0% RH, some droplets do not nucleate crystals in the time taken for all water to evaporate and dry to form an amorphous particle. We believe that this interplay between crystalline or amorphous particle formation is a result of the viscosity of aqueous NaNO3 solutions, which rises by several orders of magnitude as the concentration increases. We show that for droplets with an initial radius of ∼25 μm the propensity for aqueous NaNO3 droplets to nucleate crystals upon drying increases with a decreasing RH and increases with an increasing temperature in the range 278–306 K. This work demonstrates the importance of the drying kinetics on the propensity of evaporating droplets to nucleate crystals.

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“…The microphysics of the drying process also likely has an impact on the viability of bacteria in aerosols 3 . In spray drying the goal is to control the distribution of sizes, morphology and phase of the final droplets, which are very sensitive to processing conditions such as solvent 4,5 , temperature [6][7][8] , pH 9,10 and additional co-excipients [11][12][13] . Tailoring crystallisation is particularly important because crystal and amorphous states have fundamentally different properties: crystalline droplets are typically more stable and suitable for product storage 14,15 , whereas amorphous droplets are more easily re-dissolved into an aqueous solution droplet which is desirable for inhalable powders for respiratory drug delivery 16,17 .…”

Section: Introductionmentioning

confidence: 99%

Drying kinetics and nucleation in evaporating sodium nitrate aerosols

Robinson

¹

,

Gregson

²

,

Miles

³

et al. 2020

The Journal of Chemical Physics

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A quantitative understanding of the evaporative drying kinetics and nucleation rates of aqueous based aerosol droplets is important for a wide range of applications, from atmospheric aerosols to industrial processes such as spray drying. Here, we introduce a numerical model for interpreting measurements of the evaporation rate and phase change of drying free droplets made using a single particle approach. We explore the evaporation of aqueous sodium chloride and sodium nitrate solution droplets. Although the chloride salt is observed to reproducibly crystallise at all drying rates, the nitrate salt solution can lose virtually all of its water content without crystallising. The latter phenomenon has implications for our understanding of the competition between the drying rate and nucleation kinetics in these two systems. The nucleation model is used in combination with the measurements of crystallisation events to infer nucleation rates at varying equilibrium state points, showing that classical nucleation theory provides a good description of the crystallisation of the chloride salt but not the nitrate salt solution droplets. The reasons for this difference are considered.

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“…The microphysics of the drying process also likely has an impact on the viability of bacteria in aerosols 3 . In spray drying the goal is to control the distribution of sizes, morphology and phase of the final droplets, which are very sensitive to processing conditions such as solvent 4,5 , temperature [6][7][8] , pH 9,10 and additional co-excipients [11][12][13] . Tailoring crystallisation is particularly important because crystal and amorphous states have fundamentally different properties: crystalline droplets are typically more stable and suitable for product storage 14,15 , whereas amorphous droplets are more soluble which is desirable for inhalable powders for respiratory drug delivery 16,17 .…”

Section: Introductionmentioning

confidence: 99%

Nucleation kinetics in drying sodium nitrate aerosols

Robinson,

Gregson,

Miles

et al. 2019

Preprint

0

View full text Add to dashboard Cite

A quantitative understanding of the evaporative drying kinetics and nucleation rates of aqueous based aerosol droplets is important for a wide range of applications, from atmospheric aerosols to industrial processes such as spray drying. Here, we introduce a numerical model for interpreting measurements of the evaporation rate and phase change of drying free droplets made using a single particle approach. We explore the evaporation of aqueous sodium chloride and sodium nitrate solution droplets. Although the chloride salt is observed to reproducibly crystallise at all drying rates, the nitrate salt solution can lose virtually all of its water content without crystallising. The latter phenomenon has implications for our understanding of the competition between the drying rate and nucleation kinetics in these two systems. The nucleation model is used in combination with the measurements of crystallisation events to infer nucleation rates at varying equilibrium state points, showing that classical nucleation theory provides a good description of the crystallisation of the chloride salt but not the nitrate salt solution droplets. The reasons for this difference are considered.

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Dairy Milk Particles Made with a Mono-Disperse Droplet Spray Dryer (MDDSD) Investigated for the Effect of Fat

Cited by 16 publications

References 29 publications

Drying and Crystallization of Evaporating Sodium Nitrate Aerosol Droplets

Drying and Crystallization of Evaporating Sodium Nitrate Aerosol Droplets

Drying kinetics and nucleation in evaporating sodium nitrate aerosols

Nucleation kinetics in drying sodium nitrate aerosols

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