Table of Contents
Which techniques are used for microencapsulation?
Large number of techniques for microencapsulation include spray chilling, spray cooling, fluidized bed coating, liposome entrapment, extrusion, freeze drying, and coacervation.
Which microencapsulation technique is known as Wurster process?
AIR SUSPENSION TECHNIQUES (WURSTER) PROCESS: In this process, the drug particles are coated and dried while suspended in an upwardly moving current of air. Solutions and suspensions of coating materials in both water and volatile organic solvents are employed.
What is coacervation method of microencapsulation?
A coacervation process involves three main steps: (1) Formation of an oil-in-water emulsion, in which the oily droplets of core material are dispersed into the aqueous polymeric solution; (2) Formation of the coating induced by a change in the aqueous phase; (3) Stabilization of the coating by thermal treatment.
How does micro encapsulation work?
Microencapsulation is a technique in which chemicals are released in a controlled manner over a long period. In this process small particles or droplets are confined in a coating to give small capsules or microcapsules. The materials inside the capsules form the core and the outside coating becomes a barrier wall.
What is the purpose of microencapsulation?
The goals of microencapsulation are to coat an active compound (core) by an encapsulating agent, also known as wall material, which will isolate the active material, thereby protecting the active material from adverse changes or to hide sensory properties that are not appreciated by consumers.
What are the factors that play important role in the process of microencapsulation?
The encapsulation efficiency of the microparticle or microsphere or microcapsule depends upon different factors like concentration of the polymer, solubility of polymer in solvent, rate of solvent removal, solubility of organic solvent in water, etc.
What is centrifugal extrusion?
➢ Centrifugal extrusion is a liquid coextrusion process utilizing nozzles consisting. of a concentric orifice located on the outer circumference of a rotating cylinder. i.e., the head.
What is Wurster process?
The Wurster process is recognized as the technology for precision application of a film coating onto particulate materials such as powders, crystals, or granules, and other solid ingredients with diameters ranging from 30 µm to several centimeters.
What is coacervation process?
Coacervation is a process during which a homogeneous solution of charged macromolecules undergoes liquid–liquid phase separation, giving rise to a polymer-rich dense phase at the bottom and a transparent solution above.
What is coacervation theory?
a theory expressed by the Russian biochemist A.I. Oparin in 1936 suggesting that the origin of life was preceded by the formation of mixed colloidal units called ‘coacervates’. These are particles composed of two or more colloids which might be protein, lipid or nucleic acid.
What is macro encapsulation?
Macroencapsulation refers to PCMs encapsulated in any type of container such as tubes, spheres, or panels, which can be incorporated into building materials or serve as heat exchangers by themselves (Fig. 3.5). The size of these containers is usually larger than 1 cm (Cabeza et al., 2011).
What are the advantages of microencapsulation?
One of the most important benefits of microencapsulation is improving the stability of nutrients, preventing ingredient interactions and degradation. The coating matrix effectively separates particles and prevents them from contacting each other.
Which are components of microcapsules?
2.3. A microcapsule consists of a semi-permeable, spherical, thin, and strong polymer membrane surrounding a liquid core, with a diameter varying from a few microns to 1 mm [39]. Because of the absence of a solid or gelled core and small diameter, mass transfer limitation is reduced in microencapsulation.
What is spray drying microencapsulation?
Spray drying is one of the most widely used microencapsulation techniques, since it provides rapid evaporation of water and maintains the low temperature in the particles. Prior to spray drying, the wall material is mixed with the suspension containing encapsulated components through intensive homogenization.
Which is example of Wurster process?
Wurster processing is a bottom-spray fluidized bed process. It is a one-step, enclosed operation designed to evenly coat individual particles such as pellets with an atomized spray solution or suspension. Core particles — for example, sugar spheres — are fluidized via airflow rising from the bottom of the chamber.