This document discusses encapsulation of natural polyphenolic compounds. It describes various encapsulation methods including spray drying, supercritical fluid techniques, physicochemical methods, and chemical methods. Spray drying is highlighted as the most widely used method for encapsulating polyphenols due to its low cost, flexibility, and ability to produce stable particles. Specific polyphenols that have been encapsulated using different techniques like spray drying, supercritical fluid processes, and complex coacervation are also outlined.

1. Encapsulation of Natural Polyphenolic compounds
By
Vaibhav Kumar Maurya
PhD (BAS)
NIFTEM
5/9/2015 1

2. Polyphenolic compounds
• Secondary metabolites of vascular plants
• Derived from the metabolism of shikimic acid and polyacetate
What are the health benefits from polyphenolic compounds?
• Reduce the inflammation by inhibition of the edema
• Stop the development of tumors
• Present proapoptotic and anti-angiogenic actions
• Increase the capillary resistance by acting on the constituents of
blood vessels
• Protect the cardiovascular system
• Protect retina
• Limit weight gain
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3. Economic implication of polyphenolic compound
• Natural coloring agent
• Conservative agents
• Natural antioxidants
• Nutritional additives
• Cosmetics and pharmaceutical application
Classes of polyphenol
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1. Hydrobenzoic acids
2. Hydroxycinnamic acids
3. Coumaries
4. Stilbenes
5. Flavanols
6. Flavones
7. Flavanones
8. Isoflavones
9. Flavanols
10. Proanthocyanidins
11. Anthocyanins
12. Lignans

4. Stability of polyphenol
• Instable during processing
• Very sensitive to environmental factors
What is encapsulation ?
• Shielding to evade chemical reactions or to facilitate the
regulated discharge of core bioactive ingredient from the
shell (capsule and coating) with efficient mass transport
behavior
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5. What encapsulation does?
• Protect a fragile or unstable compound fro its surrounding
environment
• Protect the user from the side effects fo the encapsulated
compound trap a compound (aroma, organic solvent, pesticide
essential oil etc)
• Modify the density of a liquid
• Change a liquid into a solid
• Isolate two incompatible compounds that must coexist in the
same medium
• Control the release of the encapsulated compound
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6. Encapsulation method
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Physical methods Physiochemical
methods
Chemical methods
Spray drying Spray cooling
interfacial
polycondensation
Fluid bed coating hot melt coating In situ polymerization
Extrusion-
spheronization Ionic gelation
interfacial
polymerization
centrifugal extrusion
solvent evaporation-
extraction Interfacial cross linking
Supercritical liquid
method
Simple or complex
coacervation

7. Spray drying
• Very rapid method
• Single stage method
• Continuous method
• Most widely method
• Economical, flexible method
• High quality and stable particle
• Wide particle size range (10-100µm)
• Wide selection range for wall material
Wall material
• Secondary food grade material, non
reactive to food matrix as well as to
bioactive core ingredient used for covering
bioactive material
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Fig 1: Schematic illustration of a
spray- drying apparatus.

8. Widely used wall material for polyphenols
• Protein (Sodium caseinate and gelatin)
• Hydrocolloid (gum arabic)
• Hydrolyzed starch ( starch, lactose and maltodextrin)
• Chitosan
Natural product encapsulated by Spray drying
• Soybean extract
• Grape seed extract
• Artichoke
• Oak extract
• Yerba mate
5/9/2015 8Fig 2: Scanning electron micrographs of (a) blank microspheres and (b)
microspheres loaded with olive tree leaves extract (OLE)

9. Encapsulation process using supercritical Fluid
• Can be classified into
1. As solvent: Rapid Expansion of Supercritical
Solution(RESS) and derived process
2. As an anti-solvent: Supercritical Anti Solvent(SAS) and
derived processes
3. As a Solute: Particle from Gas Saturated Solution (PGSS)
and derived processes
• Supercritical Anti Solvent and Gas Saturated Solution
methods are widely used for polyphenol encapsulation
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10. Supercritical Antisolvent
Processing
• Heterogeneous particle size
distribution
• Anti solvent dissolves in the
solution by decreasing its density
and the solvation power of the
organic solvent
• Solvent evaporates in the
supercritical phase, leading to
the oversaturation of the
solution, then to precipitation of
the solute.
• Excess of solvent is eliminated
under a continuous flow of pure
supercritical fluid via a purge
gate
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ss
Fig 3: (A) SEM micrographs of the green tea extract co-precipitated with
polycaprolactone (PCL) (MW: 25,000) by Supercritical Antisolvent Process and (B)
schematic diagram of the SAS pilot plant
B

11. Gas Saturated
Solutions Process
• Supercritical fluid plays the
role of a solute
• Under pressure gases can be
dissolved in liquids
• Gas-saturated solution
expanded through a nozzle
into the atomization chamber,
to form solid particles or
liquid droplets
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Fig 4: Schematic flowsheet of the particles from gas saturated
solutions (PGSS) process

12. Application of Gas Saturated Solutions Process
• Gentle drying of natural extracts
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Fig 5: Scanning electron micrographs of the green tea samples produced by PGSS
drying process

13. Physicochemical
Methods
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Spray cooling
hot melt coating
Ionic gelation
solvent evaporation-extraction
Simple or complex coacervation

14. Encapsulation by Cooling of Emulsions
• Dissolving or dispersing the active compound in a melted wall material
• melted phase is then emulsified in a continuous phase heated at a higher
temperature than the melting point of the coating material
• Then environment is suddenly cooled and particles solidify
• Allows the microencapsulation of hydrophilic or lipophilic molecules if a
continuous phase is chosen for which these molecules do not have enough
affinity
Polyphenolic compound encapsulated by Cooling
of emulsion
• Black currant (BCAs) (delphinidin-3-O-glucoside, delphinidin-3-O-
rutinoside, cyanidin-3-O-glucoside and cyanidin 3-O-rutinoside
• Epigallocatechin gallate
• Quercetin
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15. Emulsification-Solvent Removal Methods
• Evaporation or extraction of the internal phase of an emulsion
giving rise to the precipitation of the polymer coating
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Fig 6: Encapsulation by (A) Emulsion/Extraction and (B) Emulsion/Evaporation
methods

16. Ionic Gelation
• Consists of extruding an aqueous solution of polymer through
a syringe needle or a nozzle
• Droplets are received in a dispersant phase and are
transformed, after reaction, into spherical gel particles
• Chitosan (88.3%)
• calcium alginate (90%)
• tea polyphenol extract
• Elsholtzia splendens extract
• Catechin and (-)-epigallocatechin
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17. Acidic Precipitation
• Acid precipitation of the casein
• Sodium caseinate
• Calcium caseinate
• China green tea
Complex Coacervation
• Based on the ability of cationic and anionic water-soluble
polymers to interact in water to form a liquid, neutral,
polymer-rich phase called coacervate
• Separation of an aqueous polymeric solution into two miscible
liquid phases: a dense coacervate phase and a dilute
equilibrium phase
• The dense coacervate phase wraps as a uniform layer around
dispersed core materials
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18. Complex Coacervation
• Technology parameters are the pH, the ionic strength, the temperature, the
molecular weight and the concentrations of the polymers
• Three steps process: formation of an oil-in-water emulsion, formation of
the coating and stabilization of the coating
• Particles are not perfectly spherical, and production cost is very high
• Useful high value active molecules or for unstable substances
• Calcium alginate and chitosan
• Pectin and soy protein
• Yerba mate extract
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Fig 7: SEM microphotographs of control (a)
dried in oven and (b) lyophilized beads;
and alginate–chitosan (c) dried in oven and
(d) lyophilized beads

19. Layer-by-Layer Process
• Deposit alternate layers of oppositely charged materials onto
mineral or organic substrates which constitute the core of the
particle
• Self-assembly technique based on electrostatic attraction of charged
polymers leading to the formation of membranes of controllable
thickness according to the number of stacked layers.
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1.Polyanion
2.wash 1.Polyanion
2.wash
Fig 8. Schematic representation of polyelectrolyte self-assembling

20. • Epigallocatechin gallate in polystyrene sulfonate/polyallylamine
hydrochloride, polyglutamic acid/poly-L-lysine, dextran sulfate/protamine
sulfate, carboxymethyl cellulose/gelatin A
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Fig 9. Scheme of gelatin A/EGCG hollow capsule preparation

21. Micelles
• Based on Hydrophobic Interactions
• In an aqueous solution, amphiphilic polymers self-organize
into supramolecular arrangements possessing a hydrophobic
central core and a hydrophilic crown
• polymer concentration in solution is higher than the critical
micellar concentration (CMC)
• Resveratrol - polycaprolactone (PCL) as the hydrophobic core
and poly(ethylene glycol) (PEG) as the hydrophilic shell
• Curcumin- N-isopropylacrylamide (NiPAAm), N-vinyl-2-
pyrrolidone and poly(ethylene glycol) acrylate
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22. Liposomes
• Artificial vesicles formed by one
or more concentric lipid bilayers
separated by water compartments
• Classes- Small unilamellar vesicles (SUV), large unilamellar vesicles
(LUV) and large multilamellar vesicles (MLV) or multivesicular vesicles
(MVV)
• Used to target, protect, release, immobilize or isolate hydrophilic,
lipophilic or amphiphilic substances
• Classical Bangham method-hydration of dried phospholipid films
• Unstabile in biological fluids and the high speed of active ingredient
release
• Payload of the active ingredient is very low
• Encapsulation efficiency of phenolic compounds depends on the
morphology of the liposome
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23. Chemical Methods
• In Situ Polymerization
• Interfacial Polycondensation and
Interfacial Cross-Linking
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24. In Situ Polymerization
• Process consists of emulsifying the monomer component in an
aqueous phase added with an appropriate surfactant
• Mostly vinylic and acrylic compounds such as styrene or
methyl methacrylate
• Polymerization having been started, the resulting water-
insoluble polymer gives microsphere
• Quercetin
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25. Interfacial Polycondensation and Interfacial
Cross-Linking
• Chemical reaction by which a membrane made of
polymers is created around emulsion droplets
• Reaction occurs at interface between the continuous and
dispersed phases. In the emulsion, each phase contains a
type of monomer
• Applied to aqueous or organic
active materials
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Fig 10: Principle of the microencapsulation by
interfacial polymerization. (A) The
oligomer is soluble in the droplet; (B) the
oligomer is insoluble in the droplet

26. Formulation parameters
• The nature of monomers,
• the nature and concentration of the surfactant used
• the properties of solvents
• the physical parameters of the stirring (speed, time, type of mobile)
Interfacial Cross-Linking
• When the water-soluble monomer is replaced by an oligomer or
polymer, this is known as interfacial cross-linking
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Fig 11. Mechanism of microcapsule
formation by interfacial cross-linking
of a hydrosoluble polymer, involving
terephthaloyl chloride as an organo-
soluble cross-linking agent.

27. Interfacial Cross-Linking
• Cross-linked grape proanthocyanidin (GPO)
• GPO with terephthaloyl chloride (TC) involves hydroxyphenolic groups
leading to the establishment of ester bonds that were detected by infrared
spectroscopy
• Cross-linked GPO microcapsules, obtained at pH 9 and 11, had a size
lower than 10 μm
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Fig 12. Scanning electron micrographs of
proanthocyanidin microcapsules (a)
prepared at pH 9.8; (b) prepared at pH 11.

28. Other Stabilization Methods
• Encapsulation in Yeasts
• Co-Crystallisation
• Molecular Inclusion
• Freeze-Drying
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29. Encapsulation in Yeasts
• Yeast cells (Saccharomyces cerevisiae) as the
encapsulant material
• Cells were emptied out of their content by autolysis using a
• Clasmolyzing agent (NaCl 5%) and the empty cells were
dispersed in an aqueous phase containing
• Chlorogenic acid, and loaded by re-swelling in this
solution
• Cheap and very effective in terms of loading
• Encapsulation of small lipophilic molecules as found in
essential oils
• Stable towards a thermal and hydric stress, whereas it did
not hinder the in vitro rele
• Chlorogenic acid
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30. Co-Crystallisation
• Introduction the aromatic compound into a saturated solution of
sucrose
• Spontaneous crystallization of this syrup is realized at high
temperatures (above 120 °C) and with a low degree of humidity
• The crystal structure of sucrose is modified, and small crystal
aggregates (lower than 30 μm) trapping the active molecule are
formed
• Granular product have -very low hygroscopicity, a good fluidity and
a better stability
• Good economic alternative and remains a flexible technique because
of its simplicity.
• Crystals had a size between 2 and 30 μm
• Yerba mate extract
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31. Molecular Inclusion
• Appeals to cyclodextrins (CDs). CDs represent a family of cyclic
oligosaccharides consisting of glucopyranose subunits bound through α-
(1,4) links
• Three classes: α-, β- and γ-cyclodextrins, composed of 6, 7 or 8 subunits
• Cyclic molecules possess a cage-like supramolecular structure, able to
encapsulate various guest molecules
• Resveratrol
• Live leaf extract
• Kaempferol
• Quercetin
• Myricetin
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Figure 14. Molecular model of inclusion complex ferulic acid/α-CD

32. Freeze-Drying
• Most used processes for the protection of thermosensitive and
unstable molecules
• Dehydration operation at low temperature consisting in
eliminating water by sublimation of the frozen product
• Polyphenol-rich raspberry
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33. 5/9/2015 33