Rotor-stator Homogenization Research Articles

Improvement of mechanical properties of chitosan-based films via physical treatment of film-forming solution

Although biopolymer films are of interest from many points of view, these films have inferior mechanical properties to commercially available synthetic polymer films. The present study therefore aimed to seek a means to improve the mechanical properties of biopolymer films; chitosan was chosen as the biopolymer of interest. The effects of selected physical methods that can be incorporated into the film-forming solution preparation process were investigated. Heat treatment by heating the film-forming solution at 70°C for 1h to induce thermal cross-linkage of chitosan polymer chains was evaluated. In addition, the effects of some processes that led to the homogenization of the chitosan solution and plasticizer (glycerol) were tested. These included rotor–stator homogenization at 9600rpm at atmospheric pressure and two-stage high-pressure homogenization at a gauge pressure of either 10/5, 20/5 or 30/5MPa. The prepared film-forming solutions were then dried by hot air drying at 40°C and the obtained films were tested for their properties and characteristics in terms of the tensile strength, percent elongation, X-ray diffraction as well as dynamic mechanical analysis patterns. Chitosan film exhibiting the best mechanical properties was the one prepared from the film solution that did not pass through the heat treatment but passed through the high-pressure homogenization at 10/5MPa, with the tensile strength and percent elongation of about 46MPa and 36%, respectively. Compared to the control film, there was an increase of about 23% in the tensile strength and 25% in the percent elongation.

Microencapsulation of Extra Virgin Olive Oil by Spray Drying: Effect of Wall Materials Composition, Process Conditions, and Emulsification Method

The objective of the study was to investigate the microencapsulation of extra virgin olive oil by spray drying to increase its stability and application area. The effects of homogenization rate, pump rate, i.e., flow rate of feeding emulsion and wall materials composition on physical and chemical properties of microencapsulated extra virgin olive oil powder (MEVOP) were evaluated. Maltodextrin (MD) and whey protein isolate (WPI) were used as wall materials and microencapsulation was carried out in a laboratory type spray dryer. The MD:WPI ratio as mixture variable and pump and homogenization rates as process variables were arranged through D-optimal combined design. The optimum wall materials composition and microencapsulation process conditions were determined as follows: 92 % (db) MD, 7 % (db) WPI, and 1 % (db) Tween 20 as wall materials composition and 17,500 rpm and 22 % homogenization and pump rates, respectively. The results showed that the wall materials composition was the most effective independent variables on physical properties in terms of moisture content, water activity, bulk and particle properties of powder as well as microencapsulation efficiency and oxidation stability of MEVOP during converting liquid extra virgin olive oil to powder form. The effects of emulsification methods in terms of rotor-stator and ultrasonic homogenization on physical and chemical properties of MEVOP were also comparatively investigated in this study. The MEVOP produced by ultrasonic homogenization had smaller particle size and lower microencapsulation efficiency than that of rotor-stator homogenization method. But microcapsules obtained by ultrasonic homogenization had better oxidative stability.

Preparation and in vivo toxicity study of solid lipid microparticles as carrier for pulmonary administration

The purpose of this research was to investigate the effects of processing conditions on the characteristics of solid lipid microparticles (SLM) with a potential application as carriers for pulmonary administration. Compritol (5.0% wt/wt) SLM dispersions were prepared by rotor-stator homogenization, at different surfactant concentrations and emulsification times. The SLM were characterized, in terms of morphology and size, after lyophilization and sterilization by autoclaving process. In vivo assessment was carried out in rats by intratracheal instillation of either placebo or SLM dispersion, and by bronchoalveolar lavage for cytological analysis. Mean particle size of 4 to 5 microm was achieved using 0.3% and 0.4% (wt/wt) of emulsifier (Poloxamer 188) and emulsification times of 2 and 5 minutes. The particles showed spherical shape and smooth surface. The morphology of microparticles, the size, and the size distribution were not substantially modified after lyophilization and sterilization. Total cell counts showed no significant differences between placebo and SLM 0.5% or 2.5% groups. Regarding cytology, percentage of polymorphonuclear neutrophils and macrophages did not significantly differ between groups. These results suggest that a single intratracheal administration of the SLMs does not induce a significant inflammatory airway response in rats and that the SLMs might be a potential carrier for encapsulated drug via the pulmonary route.