Applications of extrusion in encapsulation technology

1. Applications of extrusion in
encapsulation technology
Presented by SYED AASIF MUJTABA
14pft012

2. Extrusion technology: introduction
• Operation of shaping a dough like material
by forcing it through a restriction/die.
• Widely used in FPI.
• In food extrusion, the food material is
forced to flow under one/more varieties of
conditions of mixing, heating & shear
through a die designed to form/puff the
dry ingredients.
• A food extruder is a device used to cook,
form, mix, texturize, shape & restructure
the food ingredients.

3. Types of food extrusion process
Cold Extrusion Hot Extrusion
• process at room temperature/ slightly
elevated temperature.
•No thermal energy addition.
•Specific shape products (pasta, pastry
dough, candy pieces, meat products).
•Low pressure extrusion is used to
produce,eg. liquorice , fish pastes,
surimi and pet foods.
•No oxidation takes place.
• Good mechanical properties
(temp. are below the re-
crystallization temp.)
•Above 100*C.
•Also called extrusion cooking.
•Thermal energy addition.
•Widely used to produce a
range of products(variety of
low density, expanded snack
foods and RTE puffed cereals
•HTST process (microbial
contamination and inactivates
enzymes)

4. Functions of extruders
Agglomeration Degassing
Dehydration Expansion
Gelatinization Grinding
Homogenization Mixing
Pasteurization & sterilization Protein denaturation
Shaping Shearing
Texture alteration Thermal cooking
Unitizing

5. Encapsulation
Defined as a process to entrap active agents within a carrier material (wall
material)
A useful tool to improve delivery of bioactive molecules and living cells into
foods
A technology in which the bioactive components are completely enveloped ,
covered and protected by a physical barrier
A technology of packaging solids liquds or gaseous materials in small capsules
that release their contents at controlled rates over
Produced particles usually have diameters of a few nm to a few mm
Encapsulation technology is now well developed and accepted within the
pharmaceutical, chemical, cosmetic, foods and printing industries. In food
products, fats and oils, aroma compounds and oleoresins, vitamins, minerals,
colorants, and enzymes have been encapsulated

6. The substance that is encapsulated may be called the core material, the
active agent, fill, internal phase, or payload phase
The substance that is encapsulating may be called the coating,
membrane, shell, carrier material, wall material, capsule, external phase,
or matrix.

7. Two main types of encapsulates
The reservoir type: • has a shell around the active agent. • This type is
also called capsule, single-core, mono-core or core-shell type
The matrix type • The active agent is much more dispersed over the
carrier material; it can be in the form of relatively small droplets or more
homogenously distributed over the encapsulate. • Active agents in the
matrix type of encapsulates are in general also present at the surface
(unless they have an additional coating)

8. The main purposes of encapsulation
stabilize an active
ingredient
control its release
rate
and convert a
liquid formulation
into a solid which
is easier to handle
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9. Protective shell specifications
maximal protection against
environmental conditions, during
processing or storage under various
conditions
not to react with the encapsulated
material
have good rheological
characteristics at high
concentration if it is needed
have easy work ability during the
encapsulation
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10. Materials used for encapsulation
Polysaccharides
• Starch and their derivates – amylose, amylopectin, dextrins, maltodextrins, polydextrose,
syrups and cellulose and their derivatives
Plant extracts
• gum Arabic, galactomannans, pectins and soluble soybean polysaccharides
Marine extracts
• carageenans and alginate
Proteins
• milk and whey proteins are caseins, gelatin and gluten.
Lipids
• fatty acids and fatty alcohols, waxes (beeswax, carnauba wax, candellia wax), glycerides and
phospholipids.
Microbial and animal polysaccharides
• dextran, chitosan, xanthan and gellan
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11. The reasons why to employ an encapsulation
technology?
• provide barriers between sensitive bioactive materials and the environment
• mask bad tasting or smelling,
• stabilize food ingredients or increase their bioavailability
• provide improved stability in final products and during processing.
• less evaporation and degradation of volatile actives, such as aroma
• mask unpleasant feelings during eating, such as bitter taste and astringency of
polyphenols
• prevent reaction with other components in food products such as oxygen or water
• immobilize cells or enzymes in food processing applications, such as fermentation
process and metabolite reduction processes
• improve delivery of bioactive molecules (e.g. antioxidants, minerals, vitamins,
phytosterols, lutein, fatty acids, lycopene) and living cells (e.g. probiotics) into foods
• modification of physical characteristics of the original material for (a) allow easier
handling, (b) to help separate the components of the mixture that would otherwise react
with one another, (c) to provide an adequate concentration and uniform dispersion of an
active agent

12. Extrusion in encapsulation
• exclusively for the encapsulation of volatile and unstable flavors in glassy
carbohydrate matrices
• this process has the very long shelf life imparted to normally oxidation-prone flavor
compounds, such as citrus oils, because atmosphere gases diffuse very slowly through
the hydrophilic glassy matrix, thus providing an almost impermeable barrier against
oxygen.
• Carbohydrate matrices in the glassy states have very good barrier properties and
extrusion is a convenient process enabling the encapsulation of flavors in such matrices
• allows the encapsulation of heat-sensitive material, such as Lactobacillus acidophilus,
which cannot be achieved in a typical carbohydrate matrix because of the much higher
processing temperatures typically used.
• The very low water content in the extruding mass prevents the degradation of the
enzyme even at high temperatures for short periods of time

13. Equipment
 In the feed zone, a low pressure is generated to homogenize the feeding.
 In the subsequent zone(s), a gradual increase in pressure is achieved via the screw
design to melt, further homogenize, and compress the extrude.
 In the final part of the barrel, a constant screw design helps to maintain a continuous
high pressure to ensure a uniform delivery rate of molten material out of the extruder.
 The barrel is also divided into sections to allow for section-controlled variation in
temperature.
 Addition of the active ingredient might be in the mixing/dispersing zone of the extruder
at about halfway to minimizes the residence time of the active ingredients
 At the end of the barrel, a “pre die” and “die head” determine the shape of the final
product (e.g., sheets, ropes or threads). It can be equipped with a chopper/cutter to
obtain granular extrudates.

14. Extrusion
advantages
•very long shelf life
•Resistance to oxidation
• for heat sensitive materials(bacteria & enzymes)
disadvantages
•Cost in use
•Increase in carbohydrate in food
•Large particles (500-1000 μm)
•Limited range of shell material
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15. Flavor encapsulation
• Encapsulation of flavors consists in protecting a flavoring agent or a
mixture of molecules with a dedicated envelope. Encapsulation can
limit the degradation or loss of flavor during the various product
processes and storage. The envelope can also provide functional
properties, such as a controlled release of aromatic molecules in a
given environment like water (if flavored tea), mouth (solid food:
candy, toothpaste

16. The encapsulation of flavors via twin screw
melt extrusion
• the remarkable properties of distributive and dispersive mixing of the
twin screw extruder are used to encapsulate flavors continuously.
• The matrix powder is first metered into the extruder and then
conveyed and mixed by the screws. By use of viscous dissipation and
controlled heating, the powder is melted and transformed into a
viscous dough. Aromatics, usually in liquid form, are then accurately
introduced into a barrel module during the process: the screw
configuration is adjusted to disperse the small droplets of liquid
flavors into the molten matrix and distribute them regularly throughout
the mass. Temperature and screw shear should be controlled to secure
the new homogeneous mixture at a specific and stable viscosity and
avoid aggregation of the small droplets

17. Applications of encapsulated flavors
• Extruded encapsulated flavors are used as ingredients in the food industry
for applications such as rapid preparations for desserts, cakes and biscuits,
tea bags, loose tea, coffee, instant drinks and confectionery.
• The advantages of twin-screw extrusion for encapsulating flavours
• Continuous and precise processing with reduced manufacturing costs
without producing effluents
• A secured and easily installed compact processing unit
• A wide range of flavors and combinations of matrices
• Excellent dispersion in the protective matrix
• Ability to control the flavors dispersion parameters
• Highly-efficient protection, enabling long storage and shelf life (2 to 3
years

18. very long shelf life
a few months for
unencapsulated citrus
oils
1 year for spray dried
flavors
5 years for extruded
flavor oils
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19. Fish oil encapsulation
• Fish oil can be encapsulated into a formable mixture by using an
extruder with one or more screws in a continuous process .the
extrusion process is done at a relatively low temperature (below
30°c)and low pressures (500 – 5,000 K pa)
• This can be achieved by using relatively high amounts of plasticizer .
First,emulsions using proteins ,gum or modified matrix (composed of
malto-dextrin) by melt extrusion to enhance the storage stability.

20. Extrusion of probiotics
Extrusion is the oldest and most common methods widely used to
form microcapsules of hydrocolloid gel matrices due to its ease,
simplicity, low cost and gentle condition , ensuring high level of
entrapped probiotics.
The mixture of hydrocolloid solution (such as alginate and
carrageenan) and the suspension of probiotic cultures is extruded
through a syringe needle as droplets into a hardening solution such
as calcium chloride.
The size and shape of the beads were influenced by many
factors as the needle diameter, distance between needle and
hardening solution as well as the surface tension of the hardening
solution.
.

21. • This method produced the beads size of 2-5 mm ,
affecting to sensory characteristics of the applied food
products.
• Nevertheless, the microencapsulated probiotics were
well protected in the beads against the harmful condition
of simulated gastric and intestinal juices as well as in
food products

22. Centrifugal extrusion
Centrifugal extrusion is another encapsulated
technique that has been investigated and is currently used
by some vitamin manufacturers for the encapsulation of
vitamin A.
The device used in this encapsulation technique
consists of a concentric feed tube through which coating
material and core material are pumped separately to the
many nozzles mounted on the other surface of the device.
Core material flows through the center of the tube; coating
material flows through the other tube.

23. The entire device is attached to a rotating shaft such that
the head rotates around its vertical axis. As the head rotates, the
core material and coating material are co-extruded through the
concentric orifices of the nozzles as a fluid rod of core sheathed
in coating material.
Centrifugal force impels the rod outward, causing it to
break into tiny particles. By the action of surface tension, the
coating material envelops the core material, thus accomplishing
encapsulation. The capsules are collected on a moving bed of
fine-grained starch, which cushions their impact and absorbs
unwanted coating moisture. Particles produced by this method
have diameters ranging from 150 to 2000 µm