Academic literature on the topic 'Electrostatic Spray Drying'

Using melamine formaldehyde (MF) microspheres as hard templates and silica colloid as shell precursors, core-shell structures of silica-coated MF microspheres were prepared by the electrostatic adsorption process or spray drying inspired in-situ coating and drying process. Furthermore, nanometer- and micrometer-sized silica hollow spheres were obtained by calcinations in air. The influence of preparation methods and ratio of silica colloid to MF microspheres on the composition, the morphology and size of the core-shell intermediates and the hollow spheres were studied with FTIR, SEM and TEM techniques.

Oregano essential oil (EO) enteric release powder was formulated by spray drying feed emulsions stabilized with polysaccharides (PSC) and Eudragit® L100 (PLM). Different modified starches were used in the PSC component. Spray-dried powders were evaluated for particle size and morphology, dynamic packing, flowability, chemical interactions, reconstitution, and gastric protection. Feed emulsions were stable, indicating the good emulsification ability of the PLM/PSC combination. The presence of polymer in the encapsulating wall neutralized electrostatic charges indicating physical attraction, and FTIR spectra showed peaks of both PLM and PSC without significant shifting. Furthermore, the presence of polymer influenced spray drying, resulting in the elimination of surface cavities and the improvement of powder packing and flowability, which was best when the surface-active, low-viscosity sodium octenyl succinate starch was used (angle of repose 42°). When a PLM/PSC ratio of 80/20 was used in the encapsulating wall, the spray-dried product showed negligible re-emulsification and less than 15% release in pH 1.2 medium for 2 h, confirming gastric protection, whereas at pH 6.8, it provided complete re-emulsification and release. In conclusion, (1) polymer–PSC physical interaction promoted the formation of a smoother particle surface and product with improved technological properties, which is important for further processing, and (2) the gastro protective function of Eudragit® L100 was not impaired due to the absence of significant chemical interactions.

Recently, submicron particles have been discussed as a means to increase the bioavailability of poorly water-soluble drugs. Separation of these small particles is done with both fibre and membrane filters, as well as electrostatic precipitators. A major disadvantage of an electrostatic precipitator (ESP) is the agglomerate formation on the precipitation electrode. These agglomerates frequently show low bioavailability, due to the decreased specific surface area and poor wettability. In this work, a new melt electrostatic precipitator was developed and tested to convert submicron particles into a solid dispersion in order to increase the bioavailability of active pharmaceutical ingredients. The submicron particles were generated by spray drying and transferred to the ESP, where the collection electrode is covered with a melt, which served as matrix after solidification. The newly developed melt electrostatic precipitator was able to collect isolated naproxen particles in a molten carrier. A solid naproxen xylitol dispersion was prepared, which showed a reduction of the dissolution time by 82%, and a release of 80% of the total drug, compared to the physical mixture.

Alginates gel rapidly under ambient conditions and have widely documented potential to form protective matrices for sensitive bioactive cargo. Most commonly, alginate gelation occurs via calcium mediated electrostatic crosslinks between the linear polyuronic acid polymers. A recent breakthrough to form crosslinked alginate microcapsules (CLAMs) by in situ gelation during spray drying (“CLAMs process”) has demonstrated applications in protection and controlled delivery of bioactives in food, cosmetics, and agriculture. The extent of crosslinking of alginates in CLAMs impacts the effectiveness of its barrier properties. For example, higher crosslinking extents can improve oxidative stability and limit diffusion of the encapsulated cargo. Crosslinking in CLAMs can be controlled by varying the calcium to alginate ratio; however, the choice of alginates used in the process also influences the ultimate extent of crosslinking. To understand how to select alginates to target crosslinking in CLAMs, we examined the roles of alginate molecular properties. A surprise finding was the formation of alginic acid gelling in the CLAMs that is a consequence of simultaneous and rapid pH reduction and moisture removal that occurs during spray drying. Thus, spray dried CLAMs gelation is due to calcium crosslinking and alginic acid formation, and unlike external gelation methods, is insensitive to the molecular composition of the alginates. The ‘extent of gelation’ of spray dried CLAMs is influenced by the molecular weights of the alginates at saturating calcium concentrations. Alginate viscosity correlates with molecular weight; thus, viscosity is a convenient criterion for selecting commercial alginates to target gelation extent in CLAMs.

Enzymatic hydrolysis of food proteins is convenient method to improve their functional properties and physiological activity. Herein, the successful covalent attachment of alcalase on alginate micron and submicron beads using the carbodiimide based chemistry reaction and the subsequent application of the beads for egg white and soy proteins hydrolysis were studied. In addition to the electrostatic extrusion technique (EE) previously used by others, the potential utilization of a novel ultrasonic spray atomization technique without drying (UA) and with drying (UAD) for alginate submicron beads production has been attempted. The immobilization parameters were optimized on microbeads obtained by EE technique (803 ± 23 µm) with respect to enzyme loading and alcalase activity. UA and UAD techniques resulted in much smaller particles (607 ± 103 nm and 394 ± 51 nm in diameter, respectively), enabling even higher enzyme loading of 671.6 ± 4 mg g−1 on the carrier and the highest immobilized alcalase activity of 2716.1 IU g−1 in the standard reaction. The UAD biocatalyst exhibited also better performances in the real food system based on egg white or soy proteins. It has been shown that the immobilized alcalase can be reused in seven successive soy protein hydrolysis cycles with a little decrease in the activity.

Orientadores: Miriam Dupas Hubinger, Vanessa Martins da Silva
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-08-22T08:01:27Z (GMT). No. of bitstreams: 1 Carvalho_AnaGabrieladaSilva_M.pdf: 18654651 bytes, checksum: b9cbc1f805b1d0974af4067819e06088 (MD5) Previous issue date: 2013
Resumo: O óleo de café verde merece destaque na área cosmética por sua capacidade de bloquear a radiação solar UVB (290-320 nm) e por suas propriedades emolientes. Nesse contexto, para melhor aproveitar as propriedades desse óleo e aumentar a sua estabilidade oxidativa, pretendeu-se com este trabalho produzir micropartículas de óleo de café verde, pelo processo físico de spray drying. Como agentes encapsulantes foram utilizados lecitina, um fosfolipídeo de caráter aniônico quando em pH 3,0, quitosana, um polissacarídeo de caráter catiônico também em pH 3,0 e solúvel somente em sistemas ácidos diluídos, além de sólidos de xarope de milho ou amidos modificados derivados do milho, HiCap 100 e Snow-Flake. O preparo das emulsões foi feito através da técnica de estabilização por atração eletrostática de cargas opostas entre a lecitina e a quitosana. Com o propósito de se obter emulsões com dupla camada estáveis à separação de fase, foi utilizado um rotor-estator e um homogeneizador a alta pressão. As emulsões foram analisadas quanto à estabilidade, distribuição de tamanho e diâmetro médio das gotas, microscopia ótica, potencial zeta e comportamento reológico. As emulsões preparadas com Snow-Flake e xarope de milho/Snow-Flake (50/50) apresentaram comportamento pseudoplástico, além de apresentarem os maiores diâmetros de gota variando de 3,70 a 5,19 µm. Contudo, as emulsões com xarope de milho, HiCap 100 e xarope de milho/HiCap 100 (50/50) apresentaram comportamento de fluidos Newtonianos e diâmetros menores de gota, entre 1,15 e 1,51 µm. Para o processo de secagem foi utilizado um secador laboratorial do tipo mini spray dryer, com temperatura do ar de secagem de 170 °C. As micropartículas obtidas foram caracterizadas em relação ao conteúdo de umidade, atividade de água, distribuição de tamanho e diâmetro médio de partículas e microestrutura. Além disso, foram também determinados: a eficiência de encapsulação, o fator de proteção solar in vitro das micropartículas e estabilidade oxidativa pelo método Rancimat. As micropartículas apresentaram diâmetro entre 14,51 e 29,19 µm e excelentes valores de eficiência de encapsulação, superiores a 84%. As partículas produzidas com os amidos modificados apresentaram formato esférico sem rachaduras ou poros, já as micropartículas produzidas com somente xarope de milho apresentaram alguns poros e rachaduras, que causaram a menor estabilidade oxidativa dessas micropartículas. As micropartículas produzidas com HiCap 100 e xarope de milho/HiCap 100 (50/50) estabilizadas por lecitina-quitosana apresentaram maior estabilidade oxidativa. O fator de proteção das partículas variou entre 1,37 e 2,45, sendo de 2,12 para o óleo de café verde puro
Abstract: The green coffee oil stands out for its ability to block the UVB radiation (290-320 nm) and its emollient property. In this context, to improve the properties of this oil and increase its stability, the aim of this work was to produce microparticles of green coffee oil by spray drying. Encapsulating agents used were lecithin, a phospholipid with anionic character at pH 3.0, chitosan, a polysaccharide with cationic character also in pH 3.0 and soluble only in diluted acid solutions and corn syrup solids or corn modified starches as HiCap 100 and Snow-Flake. Emulsions preparation involved the technique of stabilization by electrostatic attraction between lecithin and chitosan. A rotor-stator homogenizer and a high pressure homogenizer were used in order to obtain stable emulsions by electrostatic layer-by-layer deposition. The emulsions were analyzed in relation to stability, size distribution and droplet diameter, optical microscopy, zeta potential and rheological behavior. The emulsions prepared with Snow-Flake and corn syrup/Snow-Flake (50/50) showed pseudoplastic behavior, besides having the biggest droplet diameters ranging from 3.70 to 5.19 µm. However emulsions prepared with corn syrup, HiCap 100 and corn syrup/HiCap 100 (50/50) showed Newtonian behavior and smaller droplet diameters ranging from 1.15 to 1.51 µm. For the drying process, a laboratory spray dryer and air temperature of 170 °C were used. Microparticles were characterized with respect to moisture content, water activity, particle size distribution and microstructure. Furthermore, encapsulation efficiency, sun protection factor in vitro and oxidative stability by the Rancimat method were determined. The microparticles had a diameter ranging from 14.51 and 29.19 µm and high values of encapsulation efficiency, above 84%. The particles produced with modified starches showed spherical shape without cracks or pores and those produced with only corn syrup showed some holes and cracks, that caused lower oxidative stability of these microparticles. The microparticles produced with HiCap 100 and corn syrup/HiCap 100 (50/50) stabilized by lecithin-chitosan showed the highest oxidative stability. The sun protection factor of particles ranged from 1.37 and 2.45 and 2.12 for the pure green coffee oil
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Engenharia de Alimentos
Mestra em Engenharia de Alimentos