Topics: Solvent, Micro-encapsulation, Supercritical fluid Pages: 9 (1949 words) Published: March 19, 2012

Definition: It is the process by which individual particles or droplets of solid or liquid material (the core) are surrounded or coated with a continuous film of polymeric material (the shell) to produce capsules in the micrometer to millimetre range, known as microcapsules.

Microencapsulation (Cont.):
Morphology of Microcapsules: The morphology of microcapsules depends mainly on the core material and the deposition process of the shell. 1- Mononuclear (core-shell) microcapsules contain the shell around the core. 2- Polynuclear capsules have many cores enclosed within the shell. 3- Matrix encapsulation in which the core material is distributed homogeneously into the shell material. - In addition to these three basic morphologies, microcapsules can also be mononuclear with multiple shells, or they may form clusters of microcapsules.

Morphology of Microcapsules (Cont.):

Microencapsulation (Cont.):
Coating material properties: •Stabilization of core material. •Inert toward active ingredients. •Controlled release under specific conditions. •Film-forming, pliable, tasteless, stable. •Non-hygroscopic, no high viscosity, economical. •Soluble in an aqueous media or solvent, or melting. •The coating can be flexible, brittle, hard, thin etc.

Microencapsulation (Cont.):
Coating materials:

Gums: Gum arabic, sodium alginate, carageenan.

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Carbohydrates: Starch, dextran, sucrose
Celluloses: Carboxymethylcellulose, methycellulose. Lipids: Bees wax, stearic acid, phospholipids. Proteins: Gelatin, albumin.

Microencapsulation (Cont.):
Benefits of Microencapsulation:
1- microorganism and enzyme immobilization.
- Enzymes have been encapsulated in cheeses to accelerate ripening and flavor development. The encapsulated enzymes are protected from low pH and high ionic strength in the cheese. • The encapsulation of microorganisms has been used to improve stability of starter cultures.

Benefits of Microencapsulation (Cont.):

2-Protection against UV, heat, oxidation, acids, bases (e.g.colorants and vitamins). e.g. Vitamin A / monosodium glutamate appearance (white) protection (water, T, ligth) 3- Improved shelf life due to preventing degradative reactions (dehydration, oxidation). 4-Masking of taste or odours. 5- Improved processing, texture and less wastage of ingredients. - Control of hygroscopy - enhance flowability and dispersibility - dust free powder - enhance solubility

Benefits of Microencapsulation (Cont.):

6-Handling liquids as solids 7-There is a growing demand for nutritious foods for children which provides them with much needed vitamins and minerals during the growing age. Microencapsulation could deliver the much needed ingredients in children friendly and tasty way. 8- Enhance visual aspect and marketing concept.

Benefits of Microencapsulation (Cont.):

9- Carbonless copy paper was the first marketable product to employ microcapsules. A coating of microencapsulated colorless ink is applied to the top sheet of paper, and a developer is applied to the subsequent sheet. When pressure is applied by writing, the capsules break and the ink reacts with the developer to produce the dark color of the copy.

Benefits of Microencapsulation (Cont.):

10-Today's textile industry makes use of microencapsulated materials to enhance the properties of finished goods. One application increasingly utilized is the incorporation of microencapsulated phase change materials (PCMs). Phase change materials absorb and release heat in response to changes in environmental temperatures. When temperatures rise, the phase change material melts, absorbing excess heat, and feels cool. Conversely, as temperatures fall, the PCM releases heat as it solidifies, and feels warm. This property of microencapsulated phase change materials can be harnessed to increase the comfort level for users of sports equipment, clothing, building materials, etc.

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