This presentation provides an overview of microencapsulation. Microencapsulation is a process that coats solid or liquid active ingredients with thin polymeric films to form microcapsules. It has various applications including controlled drug release, separation of incompatible ingredients, and masking of unpleasant tastes or smells. The key components are the core material and coating material. Common techniques include air suspension, centrifugal extrusion, pan coating, spray drying, and solvent evaporation. Microencapsulation has many uses in pharmaceuticals, food, textiles, and other industries.

1. Presentation on the topic
MICROENCAPSULATION
Suman Kumar

2. Contents
• Introduction
• Fundamental Consideration
• Reason for Encapsulation
• Applications
• References

3. 1. Introduction
MICROENCAPSULATION is a process by which very tiny droplets
or particles of liquid or solid material are surrounded or coated
with a continuous film of polymeric material.
The product obtained by this process is called as Microcapsules.

5. Generally Micro particles consist of two components
a) Core material.
b) Coat or wall or shell material
Fundamental Consideration

6. Core Material
The material to be coated. It may be liquid or solid.
Liquid core may be dissolved or dispersed material.
Composition of core material:
 Drug or active constituent
 Additive like diluents
 Stabilizers

7. Coating Material
Inert substance which coats on core with desired thickness.
Composition of coating:
 Inert polymer
 Plasticizer
 Coloring agent
 Resins, waxes and lipids
 Release rate enhancers or retardants

8. Examples of Coating Materials
1. Water soluble resins- Gelatin, Gum Arabic, Starch, . ….
Polyvinyl alcohol.
2. Water insoluble resins- Polyethylene, Polymethacrylate, … ..
Polyamide (Nylon), Cellulose nitrate, Silicones.
3. Waxes and lipids- Paraffin, Carnauba, Beeswax, Stearic acid, . ..
Stearyl alcohol, Glyceryl stearates.
4. Enteric resins- Shellac, Cellulose acetate phthalate, Zein.

9. Type of Core materials, Coting materials and Vehicles used in
Microencapsulation.

10. Core
Material
Characteristic
Property
Purpose of
Encapsulation
Final Product
Form
Aspirin Slightly water-
soluble solid
Taste-masking; sustained
release; reduced gastric
irritation; separation of
incompatibles
Tablet or
capsule
Vitamin A
Palmitate
Nonvolatile
liquid
Stabilization to oxidation Dry powder
Isosorbide
dinitrate
Water soluble
solid
sustained release Capsule
Properties of Some Microencapsulated Core
Materials

11. REASONS FOR ENCAPSULATION
The core must be isolated from its surroundings, as
1. To protect reactive substances from the environment.
2. To convert liquid active components into a dry solid system.
3. To separate incompatible components for functional reasons.
4. To protect the immediate environment of the microcapsules
from the active components.

12. To control the rate at which it leaves the microcapsule,
as
1. To control release of the active components for delayed (timed)
….release or long-acting (sustained) release,
2. The problem may be as simple as masking the taste or odor of
….the core,
3. To Increase of bioavailability,
4. To produce a targeted drug delivery,
5. Protects the GIT from irritant effects of the drug,
6. Extension of duration of activity for an equal level of active
….agent.

13. PHARMACEUTICAL APPLICATION
 For masking the taste of bitter drugs
Sugar or flim coating is generally used for masking
unpleasent taste.
 For separation of incompatible ingredient.
Incompatible drug can be formulated together by
microencapsulation.
Ex. Aspirin and chlorophentramine
 It reduces gastic irritation of some drug.
Ex: ferrous sulphate, potassium chloride.
1

14.  It reduces volatility of certain liquid.
Ex: methyl salicylate, peppermint oil
 Useful to increase stability of drugs.
Ex: Vitamin B1 and vitamin B2
 Helpful to decrease hazards of toxic drugs
 Useful to decrease hydroscopic property of core
material.
 Useful to improve flow properties before
compression into tablet.
1

15. 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.

16. 1. Agricultural Applications
 Reduce insect populations by disrupting their mating
process.
 Protects the pheromone from oxidation and light
during storage and release.
 Pesticides are encapsulated to be released over
time, allowing farmers to apply the pesticides less
amounts than requiring very highly concentrated and
toxic initial applications followed by repeated
applications to combat the loss of efficacy due to
leaching, evaporation, and degradation.

17. • Carbonless copy paper was the first marketable
product to employ microcapsules.
• 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).
Application in day to day life

18. Food industry
Most flavorings are volatile; therefore encapsulation of
these components extends the shelf-life of these
products.
• Some ingredients are encapsulated to mask taste,
such as nutrients added to fortify a product without
compromising the product’s intended taste
Alternatively, flavors are sometimes encapsulated to
last longer, as in chewing gum.
• Ingredients can also react with components present in
the food system, which may limit bioavailability

19.  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.
 Enhance visual aspect and marketing concept.

20. Techniques to Manufacture
Microcapsules
• The technique of microencapsulation depends on the physical and
chemical properties of the material to be encapsulated.
 The stability and the biological activity of the drug should not be
affected,
 Yield and drug encapsulation efficiency should be high,
 Microsphere quality and drug release profile should be reproducible
within specified limits,
 Microsphere should not exhibit aggregation or adherence.
 Process should be usable at an industrial scale.

21. Microencapsulation Techniques

22. Microencapsulation processes with their relative
particle size ranges.
Microencapsulation
processes
Applicable core materials Approximate particle size
Air suspension Solids 35-5000 um
Coacervation phase
separation
Solids and liquids 2-5000 um
Multiorifice centrifugal Solids and liquids 1-5000 um
Solvent evaporation Solids and liquids 5-5000 um
Spray drying and congealing Solids and liquids 600 um

23. PHYSICAL OR PHYSICO-MECHANICAL
METHODS
1. Air-suspension or Wurster technique
 Inventions of Professor Dale E. Wurster
 Equipment ranging in capacities from one pound
to 990 pounds.
 Micron or submicron particles can be effectively
encapsulated by air suspension techniques.

24. AIR SUSPENSION APPARATUS

25. WORKING OF AIR SUSPENSION APPARATUS
• Microencapsulation by air suspension apparatus
consist of dispersing of solid, particulate core
material in a supporting air stream and the spray
coating on the air suspended particles.
• Within the coating chamber particles are
suspended on an upward moving air stream.
• When the particles flow through the coating zone
portion of the chamber, the coating materials
usually a polymer solution is spray applied to the
moving particles.

26. • During each pass through the coating zone,
the core materials receive an increment of
coating material.
• The cyclic process is repeated depending upon
the thickness of the coating required.
DISADVANTAGE :
Agglomeration of the particles to some larger
size is normally achieved.

27. • Processing variables that receive consideration for efficient,
effective encapsulation by air suspension techniques include the
following:
1.Density, surface area, melting point, solubility, volatility,
Crystallinity, and flow-ability of core the core material.
2.Coating material concentration (or melting point if not a solution).
3.Coating material application rate.
4.Volume of air required to support and fluidizes the core material.
5.Amount of coating material required.
6.Inlet and outlet operating temperatures

28. 2.Centrifugal extrusion
 Liquids are encapsulated using a rotating extrusion head
containing concentric nozzles.
 This process is excellent for forming particles 400–2,000
μm in diameter.
 Since the drops are formed by the breakup of a liquid jet,
the process is only suitable for liquid or slurry.
 A high production rate can be achieved, i.e., up to 22.5 kg
of microcapsules can be produced per nozzle per hour per
head.

29. Centrifugal extrusion Process

30. WOKING
• A dual fluid stream of liquid core and shell
materials is pumped through concentric tubes
and forms droplets under the influence of
vibration.
• The shell is then hardened by chemical cross
linkings, cooling, or solvent evaporation.
• Different types of extrusion nozzles have
been developed in order to optimize the
process

31. 3. Pan coating
 Oldest industrial procedures for forming small, coated
particles or tablets.
 The particles are tumbled in a pan or other device while the
coating material is applied slowly.
 Solid particles greater than 600 microns in size are
generally considered essential for effective coating.
 Medicaments are usually coated onto various spherical
substrates and then coated with protective layers of various
polymers.

32. Representation of a typical pan
coating

33. 4.SPRAY DRYING AND SPRAY CONGEALING
These methods have been used for many years
as microencapsulation techniques.Because of
certain similarities the two methods are
discussed together.
• Microencapsulation by spray-drying is a low-
cost commercial process which is mostly used
for the encapsulation of fragrances, oils and
flavors.

34. • The equipment components of a standard spray
dryer include
1. an air heater,
2. atomizer,
3. main spray chamber,
4. blower or fan,
5. cyclone and
6. product collector.

35. MICROENCAPSULATION BY SPRAY DRYING
METHOD

36. Steps: SPRAY DRYING
• Core particles are dispersed in a polymer
solution and sprayed into a hot chamber.
• The shell material solidifies onto the core
particles as the solvent evaporates.
• The microcapsules obtained are of
polynuclear or matrix type.

37.  Spray congealing can be accomplished with spray drying
equipment when the protective coating is applied as a melt.
 Core material is dispersed in a coating material melt rather than a
coating solution.
• Coating solidification (and microencapsulation) is accomplished by
spraying the hot mixture into a cool air stream.
• Airflow
• There are three modes of contact:
1. Co-current
2. Counter-current
3. Mixed-flow

38. PHYSICO-CHEMICAL METHODS
1.Coacervation-Phase Separation
 Patents of B.K. Green et al.
 Three steps carried out under continuous
agitation:
1) Formation of three immiscible chemical phases
2) Deposition of the coating
3) Rigidization of the coating

39. • Coacervation:
• - Two methods for coacervation are available,
namely
simple and complex processes.
• In simple coacervation, a desolvation agent is
added for phase separation.
• Whereas complex coacervation involves
complexation between two oppositely
charged polymers.

40. Fig: Schematic representation of the coacervation process.
• First the core material (usually an oil) is dispersed into a polymer solution (e.g., a
cationic aqueous polymer,gelatin).
• The second polymer (anionic, water soluble, gum arabic) solution is then added to
the prepared dispersion.
• Deposition of the shell material onto the core particles occurs when the two
polymers form a complex.
• This process is triggered by the addition of salt or by changing the pH, temperature
or by dilution of the medium.

41. • Finally, the prepared microcapsules are
stabilized by crosslinking (with formaldehyde),
desolvation or thermal treatment.
• Complex coacervation is used to produce
microcapsules containing fragrant oils, liquid
crystals, flavors, dyes or inks as the core
material.

42. CHEMICAL PROCESS
1. Solvent Evaporation
 In the case in which the core material is dispersed in the polymer
solution, polymer shrinks around the core. In the case in which core
material is dissolved in the coating polymer solution, a matrix - type
microcapsule is formed.
 The core materials may be either
• water - soluble or
• water - insoluble materials.
 A variety of film - forming polymers can be used as coatings.

43. 2. Polymerization
1) Interfacial polymer
• In Interfacial polymerization, the two
reactants in a …..polycondensation meet at an
interface and react rapidly.
2) In-situ polymerization
• In a few microencapsulation processes, the
direct …..polymerization of a single monomer is
carried out on the …..particle surface.

44. • e.g. Cellulose fibers are encapsulated in polyethylene while
. immersed in dry toluene. Usual deposition rates are about
…..0.5μm/min. Coating thickness ranges 0.2-75μm.
• 3) Matrix polymer
• In a number of processes, a core material is imbedded in
a …..polymeric matrix during formation of the particles.
 Prepares microcapsules containing protein solutions by
incorporating the protein in the aqueous diamine phase.

45. REFERENCE
1.Theory and practice of industrial pharmacy by
LEON LACHMAN
HERBERT A. LIEBERMAN and
JOSEPH L.KANIG
Third edition,varghese publishing house, section
III chapter 13-part three ,pages 412-429

46. 46
 Jackson L. S.; Lee K. (1991-01-01). "Microencapsulation and the food industry".
Lebensmittle–WissenschaftTechnologie.
http://cat.inist.ft/?aModele=afficheN&cpsidt=5014466. Retrieved 1991-02-02.