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Item type:Publication, Access status: with files , Spray coating of cellulose aerogel particles in a miniaturized spouted bed(Springer, 2021-07-04); ; ; ; Aim of this work is to apply protective and homogeneous shellac coating layers on the surface of hydrophilic open-pore cellulose aerogel particles with low densities ≤ 0.1 g/cm3 and high specific surface areas in the range of ~ 400–450 m2/g while keeping the aerogels’ microstructure intact during processing. For this purpose, an innovative miniaturized spouted bed setup was used. Successful process settings for application of enclosed films on aerogel surfaces without intrusion of coating material into the pores were determined. Precise control of coating layer thickness in the range of 10–50 µm was achieved due to variation of coating solution amount without agglomeration and clogging events occurring during processing. Comparison of bulk densities and specific surface areas before and after coating proved the intactness of the porous structure. Coating of particles loaded with vanillin led to controlled release, enhancing release half-life times from 20 to 1600 min. Overall, a successful strategy for coating of organic low-density aerogels was developed.Publicationtype: Journal ArticleScopus© Citations 13 218 261 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Particle formulation of hydroalcoholic rosemary (Rosmarinus officinalis L.) extracts using a spouted bedIn this study, spouted bed technology was applied to the protection and functionalization of polyphenolic rosemary extracts. First, solid–liquid extraction was performed at 25 °C with ethanol–water. The ethanol–water ratio was chosen to obtain high phenolic acid and diterpene concentrations in the extract. The selected solvent composition gave liquid extracts that could be directly added to a coating mixture for feeding into a spouted bed apparatus. Thus, no preliminary solvent exchange or evaporation of the extraction solvent to dryness was required. Food grade Paselli MD 6 maltodextrin and HiCap 100 modified starch were used as inert core and shell materials in the spouted bed encapsulation process under mild operating conditions. The antioxidant activity of the fresh extract was retained during processing, which indicated that the active constituents were preserved and quantitatively transferred into the encapsulated formulations, which were readily soluble in water. The obtained powders were composed of nearly spherical particles. Their compositions, water solubilities, and particle morphologies make them a strong candidate for food and beverage applications as natural antioxidants, preservatives, or functional ingredients.Publicationtype: Journal Article136 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Novel technique for measurement of coating layer thickness of fine and porous particles using focused ion beam(2019-02-01); ; ; ; A novel technique for the measurement of the coating layer thickness of fine particles was developed in this work based on cross-sectioning of micrometre-sized single coated particles using focused ion beam (FIB) milling. This technique was tested on two batches of aerogel particles coated with thin coatings in a spouted bed. The FIB milling procedure consisted of two steps. First, the desired part of the coated particle was removed using a high ion beam current. The resulting cross-sectioned area was then polished using a lower ion beam current to make the cross-section clearly visible. The FIB milling process was controlled with simultaneous scanning electron microscopy (SEM). Afterwards, the coating layer thickness was evaluated using the SEM images. The coating layer was successfully applied on the porous aerogel microparticles in the spouted bed. The coating uniformity of the highly porous particles increased with increasing sprayed coating solution amount, with up to 91% of the particle pores being covered. The FIB-cross-sectioning technique using an ion beam of 2.50 nA for the first milling and 0.43 nA for polishing of the surface resulted in successful generation of cross-sections of representative particles with a visible particle core and coating layer. A coating layer thickness of approximately 700 nm was achieved on particles with sizes of below 45 μm.Publicationtype: Journal Article262