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1.
The development of a new process for gentle drying, micronisation and formulation of a high viscous biopoymer
Christian Reibe, 2011, doktorska disertacija

Opis: Biopolymers are characterised by their biodegradable behaviour in certain environments. Especially the development of natural biopolymers from renewable resources is gathering increasing interest in the scientific as well as in the industrial sectors . Since Biopolymers may be tailored to specific requirements, the encapsulation of pharmaceutical compounds or flavours in biopolymers would open wide avenues for the production of controlled- release systems. Most common mechanical pulverisation processes are milling and grinding. With these processes it is not possible to produce specific morphologies like foams or hollow spheres, but always splintered edges. Encapsulation is carried out by common precipitation techniques. Gelatine, as a widely applied biopolymer, represents one example of those substances of large interest, but it is difficult to process. Especially gelatines with high molecular mass are difficult or almost impossible to be pulverized by spray drying techniques, due to their high viscosity. In the frame of this research work, an integrated high-pressure spraying, drying and pulverization process for high viscous gelatine was developed, based on a combination of the water removing effects "Evaporation" and "Gas-solubility". The resulting products were dry, free-flowing gelatine powders, still exhibiting high molecular masses. Due to the new, gentle method of processing, a completely new gelatine product with unique properties was obtained. Even the encapsulation of edible oil in high ratios was found to be possible with this new process. The characterisation was carried out by standard methods for gelatine on the one hand side, and standard procedures for characterising powders on the other hand side. The developed process was patented under the identifier "WO 002009135601 A1".
Ključne besede: High Pressure Process, Supercritical Fluids, High molecular mass Gelatine, Micronisation, CO-2 - spray drying, Encapsulation, Gelatine Powder
Objavljeno: 26.01.2011; Ogledov: 2194; Prenosov: 57
.pdf Polno besedilo (24,89 MB)

2.
Process design for flavour encapsulation into carbohydrate melts using high pressure homogenizer
Urban Feguš, 2016, doktorska disertacija

Opis: The aim of the research project was to develop encapsulated flavourings suitable for the final food applications such as chewing gums, instant teas and confectionary products. For this purpose that water soluble particles with particle size distribution 400-1500 µm and flavour loading up to 30 wt. % should be developed. In order to produce encapsulates with desired physical properties research work was divided into three project phases. The scope of Phase 1 was to select suitable carrier materials and to perform preliminary experiments using laboratory scale process set-up. Different carbohydrates (maltodextrin, simple sugars and sugar syrups) were tested and selected according to their physical characteristics and their process performance. Afterwards preliminary experiments were performed by using laboratory scale set-up. Observations were used for defining process parameters for the design and construction of the pilot plant. Phase 2 covered design and development of the pilot plant for flavour encapsulation while In Phase 3 different process parameters were tested. In the first part influence of the process parameters (processing temperature, homogenizing pressure, mass flow, temperature of the cooling media, retention time in the cooling media and ratio between cooling media and product) on the encapsulation efficiency was investigated. Experiments were performed according to the Design of Experiments (DoE) analysed using analysis of covariance (ANCOVA). Process temperature, pressure at second homogenization step and residence time in cooling media had significant effect on the encapsulation efficiency while pressure at first homogenizing step, mass flow, temperature of the cooling media and ratio between product and cooling media were nonsignificant. Increase in the process temperature (T>130 °C) resulted in paste-like product with increased moisture content up to 13,3 wt.% which was not suitable for further processing. On the other hand samples processed at lower temperature (T<130 °C) resulted in crystalline-like structure with low moisture content. Low flavour retention (<4,5 %) was observed within all samples. Results obtained by ANCOVA were used for further optimization of the process parameters (e.g. homogenizing pressure and the retention time in the cooling media). Maximum flavour load of 3,5 % was observed regardless the homogenizing pressure. Low encapsulation efficiency (η<35 %) was related to poor emulsion stability. Additionally, effect of expansion pressure on the particle size distribution was investigated. It was observed that particle size distribution was little affected by varying expansion pressure (nozzle diameter). All formulation showed similar particle size distribution in-between 40-440 µm. In the last section effect of the emulsifier, flavouring properties and carrier were studied. Emulsifiers with different HLB values were tested in order to increase encapsulation efficiency. Flavourings were selected on the basis of their composition (polarity and volatility). For the encapsulation experiments mentha arvensis oil, orange oil and compounded pineapple flavouring were used. As an alternative carrier material erythritol was used. Addition of emulsifier improved flavour retention for samples containing mentha arvensis oil, while no affect was observed within samples containing orange oil and pineapple flavouring due to the volatility and diffusion of active compounds from matrix to surrounding environment.
Ključne besede: encapsulation, carbohydrate melts, flavouring, high pressure homogenizer
Objavljeno: 25.07.2016; Ogledov: 551; Prenosov: 35
.pdf Polno besedilo (4,56 MB)

3.
Effects of ultrasound irradiation on the preparation of ethyl cellulose nanocapsules containing spirooxazine dye
Julija Volmajer Valh, Simona Vajnhandl, Lidija Škodič, Aleksandra Lobnik, Matejka Turel, Bojana Vončina, 2017, izvirni znanstveni članek

Opis: This article presents the influence of low frequency, high intensity ultrasonic irradiation on the characteristics (average size, polydispersity index) of ethyl cellulose nanocapsules encapsulating a photochromic dye. Photochromic nanocapsules were prepared by the emulsion-solvent evaporation method. The acoustic densities entering the system were systematically studied with respect to their abilities to modify and reduce the average sizes and polydispersity indexes of the nanocapsules. Scanning electron microscope, confocal laser microscope, and dynamic light scattering were utilised to characterise the structure, shape, size, and polydispersity of ethyl cellulose photochromic nanocapsules. We were able to tailor the size of the photochromic nanocapsules simply by varying the acoustic densities entering the system. At an acoustic density of 1.5 W/mL and 60 s of continuous irradiation, we were able to prepare an almost monodispersed population of the nanocapsules with an average size of 193 nm.
Ključne besede: encapsulation, ethyl cellulose microcapsules, nanocapsules
Objavljeno: 09.08.2017; Ogledov: 97; Prenosov: 0
.pdf Polno besedilo (3,31 MB)

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