microencapsulation methods - asaga -...

Microencapsulation Methods Physical Processes

CSIRO FOOD AND NUTRITION

Luz Sanguansri & MaryAnn Augustin

Short Course on Micro- and Nano-encapsulation of Functional Ingredients in Food Products World Congress on Oils & Fats and 31st Lectureship Series 31st Oct – 4th November 2015, Rosario, Argentina

Outline

• Microencapsulation Processes

• Considerations for method selection

• 5-Step process

• Encapsulant preparation

• Core incorporation

• Core dispersion or homogenisation

• Particle or droplet formation

• Matrix or shell hardening and stabilisation

• Summary

2 | Sanguansri & Augustin | CSIRO

Microencapsulation processes used for food ingredients application

3 |

Physical Processes Chemical Processes

Spray drying Simple coacervation

Spray chilling Complex coacervation

Fluid bed coating Interfacial polymerisation

Spinning disk coating Liposome encapsulation

Co-extrusion Chemical adsorbents

Carbohydrate (melt) extrusion Inclusion complexation

Screw extrusion Thermal & ionic gelation

Sanguansri & Augustin | CSIRO

Some considerations for process selection


Beadlet | Hydrogel

Technology

•Thermal gelation

•Ionic gelation

•Enzymatic gelation

•Interfacial polymerisation

•Coacervation

Powder Technology

•Spray drying

•Spray-freezing

•Spray cooling (in melt solution)

•Spray chilling (in thermogel solution)

•Impinging aerosol method

Other processes

Extrusion (solid matrix)

•spheronisation

•pellets

Emulsification (liquid)

•Primary emulsion

•Double emulsion

Multiwall protection | double encapsulation

Fluid bed coating, layering and spray granulation

Application of additional coating layers (polymer coat or lipid coat) to primary microcapsules

Multi-stage stabilisation:

stabilisation techniques, microencapsulation, thermal adaptation, and protectant addition

Process chosen must be scalable and cost effective

…based on microcapsule format


…based on size and morphology

6 | http://www.particlesciences.com/images/tb/Encapsulation-table1.jpg Sanguansri & Augustin | CSIRO

…based on structure and morphology


How do you choose which technology or process to use?

• The choice of microencapsulation method depends on…

• Properties of the core (liquid, solid, volatile)

• Requirements in the target food application

• Encapsulant material chosen

8 |

core

wall material


What do I need to know beforehand?

• Active (core): liquid/solid, hydrophilic/hydrophobic, volatile/labile

• Target application: food/feed, dry/moist/liquid, country

• Type of capsule: size, dry/wet, powder/pellets/granules

• Production: volume, batch/continuous, on-site/sub-contractor

• Storage: dry/wet, temperature, shelf life, packaging

• Further processing: process condition, point of addition

• Release: solubilisation, temperature, shear, pressure, breakage


Microencapsulation process


Microencapsulation Process – 5 Steps

1. Encapsulant (material) preparation

2. Core preparation and incorporation

3. Core dispersion and homogenisation

4. Particle/droplet formation

5. Matrix/shell hardening or stabilisation


Encapsulant preparation and core dispersion

Lipid / FatEncapsulant

Heat Disperse /

Homogenise

Encapsulant

melted

Solid Core

added

Dispersion

WaterEncapsulant

Solution

“Heat Disperse /

Homogenise

Encapsulant

materials added

Liquid Core

added

Emulsion

Oil core in aqueous solution Solid core in lipid melt

Encapsulant preparation

Core incorporation

Core dispersion

Particle formation

Matrix or shell stabilisation

homogenise homogenise


Dispersion & Homogenisation systems…

Batch system Continuous system

Emulsion systems

Core Dispersed phase

Encapsulant Continuous phase


Core incorporation

Core dispersion

Particle formation



Dripping technologies

Poncelet (2011)


Core incorporation

Core dispersion

Particle formation



Spray/atomisation technologies

Poncelet (2011)


Core incorporation

Core dispersion or homogenisation

Particle or droplet

formation

Matrix or shell hardening and

stabilisation

Atomisation of liquid droplets in air


Spray Drying


Spray drying

Burgain et al 2011, Food Eng

formulation is atomized as

droplets

Solution, suspension, dispersion,

emulsion with added bioactive

Spray dried microcapsules

Schematic presentation of the spray-drying procedure


Core incorporation

Core dispersion or homogenisation

Particle or droplet

formation


stabilisation


Omega-3 oil encapsulation (example)

Water Encapsulant

Solution

Spray Drying

Chamber

Cyclone

Separator

Hot Air

Microencapsulated

Powder

Feed to the dryer

Heat Homogenise

Encapsulant

materials added Oil Core

added


Core incorporation

Core Dispersion or homogenisation

Particle or Droplet

formation


stabilisation

Emulsion preparation Spray Drying

Emulsion - droplets Size: 0.2-10 µm Powder - particles Size: 30-100 µm


Probiotic encapsulation (example)


Core incorporation


Particle or Droplet

formation


stabilisation

Suspension preparation Spray Drying

Probiotic suspension Size: 5-10 µm Powder - particles Size: 30-100 µm

Water

Microcapsule

Probiotics(LGG)

Encapsulant matrix

Protein RS Starch

Protein + CHO Solution

Spray Drying Chamber

Cyclone Separator

Hot Air

Microencapsulated Powder

Probiotic +Encapsulant

Mixture


Spray drying

• Most common process to convert liquid to powder

• Spray aqueous solution/dispersion in hot air

• Large throughput - capacity several tones per hour

• Produce free flowing, fine to granulated powders

• Low thermal effect on materials during drying

• Versatile and readily available in the food industry


Spray Drying

Factors affecting microcapsule properties • Feed to the dryer

– Core type and payload

– Stability of the core and the emulsion/dispersion

– Total solids and viscosity of the feed

– Encapsulant material

• Process conditions – Homogenization

– Atomization

– Drying temperature (inlet and outlet)

– Air flow (co-current / counter-current)


Spray Drying

Application

• Conversion of liquid ingredients in aqueous solution or dispersions

• Microencapsulation of flavors, vitamins, minerals, probiotics, enzymes, colors, acidulants, food additives, lipids, lipid soluble bioactives, extracts, etc.



Spray Drying

Factors influencing stability

• Oxidation - encapsulant matrix - most important! DE effects, source variation, and Aw

• Physical - emulsion - carrier and homogenization

• Diffusional losses - carrier! Tg

• Caking - carrier (environment Aw) (silica)

23 | Reineccius G 2001 | Shen et al 2010


Spray Drying

Factors affecting retention of volatiles

• Type of volatile

• In-feed solids

• Encapsulant material

• Homogenization

• Dryer temperatures

• Load (20% in industry - high load implications)

• Air flows (fixed by design)

0

10

20

30

40

50

60

70

80

90

ET

HY

L

AC

ET

AT

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HY

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PR

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ION

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24 | Reineccius G, 2001


Spray Drying

Factors affecting retention of volatiles

• Type of volatile

• In-feed solids

• Wall material

• Homogenization

• Dryer temperatures



CARRIER TYPE

0

20

40

60

80

30 40 50 60

INFEED SOLIDS (%)

RE

TE

NT

ION

(%

)

GUM ACACIA

N-LOK

MALTRIN M-100

DRYING TEMPS

30405060708090

70 80 90 100

EXIT AIR TEMP (C)

RE

TE

NT

ION

(%

)

INLET 247C

INLET 205C

INLET 163C

25 | Reineccius G, 2001


Spray Drying

Factors affecting powder characteristics

• Dryer temperatures (Ti)

– Bulk density

– solubility



26 | Fazaeli et al 2012, Food Bio Proc, 90(4): 667-675

Prilling

Spray cooling Spray chilling Congealing


Spray cooling / spray chilling

Sanguansri & Augustin | CSIRO 28 |

1000 kg

High melting

Fat

Warming to 90 °C

9 hours

Mixing 30 min200 kg

active

Blender

X m3 /h AirCooling to 4 °C

Heat exchanger

Reactor

Atomisation

600 kg / h

Cooling20 °c

Warming 20 °C

heat

exchange

Sieving

500 < d < 1500 µm

Cyclonic

/ Filtration

Cooling chamber


Core incorporation


Particle or Droplet

formation


stabilisation

Spray cooling / spray chilling


Melt tank

Cooling chamber

Spray cooling / Spray chilling

• Similar to spray drying but no water is evaporated and uses cold air

• Active is dispersed in a lipid melt or thermogel solution, emulsion or suspension

– spray lipid melt into cold air, allow to solidify & collect as powder

– spray thermogel solution into cold air, collect gelled particles (can be dried afterwards)

• Active on the surface can be washed with solvent



Processing considerations

• Active solubility/dispersibility in lipid melt or thermogel

solution

• Melting point (is active stable)

• Solidification point (stability during handling and storage)

• Heat of crystallization / solidification




• Particle size determined by:

– atomization (no shrinkage), but limited by

– time available to solidify (not dehydrate)

– air temperatures - limited by economics

– matrix viscosity (use of additives e.g. stearic acid plus ethylcellulose)

32 |

Microspheres obtained by prilling / spray chilling

(scale bar: 300 μm).

Spray cooling / Spray chilling benefits

Application

• Examples: antioxidants, vitamins, nutritional oils, proteins, enzymes, acidulants in meat products, flavorings, leavening agents, high potency sweeteners (aspartame), yeasts, probiotics, minerals, etc

• Improve heat stability

• Delay release in wet environment

• Least expensive




Factors affecting physical properties

• Melting point is critical parameter. Determined by:

- determined by fat crystalline structure

- fat/wax/polymer itself

• Influences release properties, flowability, and “caking”

34 |



Factors influencing stability of active

• Encapsulant/matrix dependent

– Permeability of matrix by active - liquid/solid, solubility, etc.

– Wall thickness - uniformity

– Permeability of matrix by oxygen or moisture

– Permeability/solubility – other food components

35 |

Coating Technologies


Particle Coating technologies

Poncelet (2011) Microencapsulation workshop 37 | Sanguansri & Augustin | CSIRO

Fluid bed coating

• Spray coating • spray a film forming encapsulant in hot

air

• Solidification – evaporation by drying air

• Hot melt coating

• Spray hot melt (lipid) in cold air

• Solidification - cooling to solidify the melt

• Dry powder coating /

• Spray fine powder and plasticising agent in ambient air

• Adsorption, sticking, coalescence


Fluid bed coating application


Coating – layering Hot melt coating

Spraying Wetting Recrystalisation Coated Particles

Single wall multiple wall

Meiners JA, 2012, Woodhead Publishing Google images

Fluid bed coating stabilisation

evaporat ion(drying)

coatingspray

impact, spreading,adhesion, coalescence

Cooling air

hot meltcoat ingspray

impact, spreading,adhesion, coalescence

evaporat ion(drying)

binderspray

powderspray

Drying Cooling (hot melt) Sticking / adsorption

Slow - high quality

Fast - good quality

Fast - Room temperature

40 | Sanguansri & Augustin | CSIRO Poncelet (2011)

Example – Probiotic powder coating


1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

0 1 3 5 7

Via

bil

ity

Loss

[(c

fu/g

)/(c

fu/g

)0]

Accelerated Storage (25°C x 57%RH) Time (week)

No coating

Shellac & wax coatedMicrogranule + coating

Microgranule (No coating)

Ying et al 2015, Food Aust

0

1

2

3

4

5

6

Moi

stur

e up

take

(g

H2O

/100

g so

lids)

Time (min)

Microcapsule pellets without-coating

Microcapsule pellets with shellac-coating

H2O

BacteriaLGG

H2O

ShellacCoating

t1 t2

BacteriaLGG

Expected theoretical maximum moisture uptake of the shellac coated pellets

100 200 300 400 500

Example probiotic coating

42 | Sanguansri & Augustin | CSIRO Ying et al (????) Bioencapsulation

Spinning disk coating


Spinning-disk coating

Sanguansri & Augustin | CSIRO 44 | Particle Coating Technologies, USA. Southwest Research Institute, USA

The solid core is suspended in a liquid encapsulant

material. The suspension is passed over a rotating disk

under controlled conditions

Spinning-disk coating


• Similar to centrifugal extrusion

• the spinning disk uses rotational forces to create droplets

• Active ingredient is suspended in a wall material and dropped onto the rotating disk

• Throws the droplets out towards the circumference, the wall material solidifies through drying or chilling

• Produce matrix particles, with narrow particle size distributions between 5 and 3000 microns

Liquid co-extrusion encapsulation

Centrifugal co-extrusion

Annular jet encapsulation


Co-extrusion technologies

Sanguansri & Augustin | CSIRO 47 | Southwest Research Institute, USA.)

The core and shell material (two immiscible liquids) are pumped through a two fluid

nozzle. The liquid stream spontaneously breaks up into droplets

Core-shell


Centrifugal Extrusion encapsulation A liquid co-extrusion process

• Nozzles consisting of concentric orifices located on the outer circumference of a rotating cylinder

• Liquid core is pumped through the inner orifice and liquid wall material through the outer orifice

• The co-extruded products breaks into droplets which forms the capsules

• The size can be as little as 150 microns

• The payload can be up to 80% by wt.

• Typical encapsulants included: gelatin, carageenan, starch, cellulose derivatives, gum arabic, fats and waxes, or polyethylene glycol.

48 |

Annular jet encapsulation


A liquid co-extrusion process

• Two concentric jets, the inner (active ingredient) and the outer (molten wall material )

• Co-extruded fluid stream naturally breaks into droplets which form the microcapsule (solidifies when exiting)

• Vibrational nozzle control the droplet size down to sub-micron diameters.

• The liquid can consist of any liquids with limited viscosities e.g. solutions, emulsions, suspensions, melts etc.

Extrusion

Carbohydrate melt extrusion High shear extrusion


Carbohydrate (melt) extrusion encapsulation

Traditional process

1. Sugar base (plus emulsifier <2%), heated to 110 – 130°C

2. Addition of flavor or other active (8 - 10%)

3. Formation of emulsion

4. Extrusion (low shear) through die (1/64" holes) into cold isopropanol bath

5. Centrifugation – to separate capsules

6. Drying

Batch process



Carbohydrate (melt) Extrusion

Melt injection process • Materials used: sucrose, maltodextrin, glucose syrup, polyols, and/or

mono- and disaccharides

• Active is mixed with molten material and pressed through one or more holes and then quenched by a cold dehydrating liquid

• The matrix material hardens on contact with the dehydrating liquid - often isopropanol and liquid nitrogen

• The size of the microcapsules is controlled by stirring – breaking up the extrudates into small pieces

• Residues of active outside the particles are washed away by the dehydrating liquid

• The microcapsules are water soluble and have particle size from 200 to 2000 microns

52 |



Factors affecting physical properties • Size - diameter largely fixed by die size, length by means

of “cutting” extrudate

• Solubility - function of matrix, size and density

• Density - generally high - result of particle forming method

• Dispersibility - rapid due to density and particle size

• Particles are generally durable

53 |



Factors influencing volatile/active retention

• Matrix composition – high sugar (caking)

• Emulsification – particle size and distribution in the matrix

• Temperatures and pressures of operation

• Volatiles incorporated - difficult to retain some volatiles (acetaldehyde, methanol, hydrogen sulfide)

• Load - usually ca. 10% although some patents claim much higher

54 |


Application:

• For encapsulation of volatile and unstable active (in glassy matrices)

• Has very long shelf life – gases diffuse very slowly through the glassy matrix

• Glassy matrices have good oxygen barrier properties


Twin screw (high shear) extrusion process


Continuous process

• Dry feed and liquid feed added separately

• Active can be added at much later stage (shorter residence time) to minimise exposure to heat

• In the feed zone low pressure is generated to homogenise the feed


Requirements

• Intensive mixing – even distribution of core

• Solids are melted – for improved efficiency and prevent blockage at the die

• Melt is cooled before die – to form & prevent flash-off of volatiles



• Very similar to melt injection - uses an extruder with single or twin screw in a continuous process

• Extrudates are dry and does not go into a dehydrating liquid/solvent

• Extrudates not limited to sugars or carbohydrates as matrix

• Matrix composed of starch, maltodextrin, modified starch, sugars, cellulose, protein, emulsifiers, lipids, and/or gums

• Core is entrapped in a continuous matrix


Summary

• The choice of microencapsulation process depends on…

– Properties of the core (liquid, solid, volatile)

– Requirements in the target food application

– Encapsulant material chosen

– Microcapsule properties (powder, size, structure, morphology)

• Develop your process taking in account commercial scale-up

• Write clear protocol that could be suitable for scale-up

• Do not forget economical aspects of your system

• It is often the COST and not the technology that hinders commercialisation


CSIRO FOOD AND NUTRITION

Thank you Luz Sanguansri Research Team Leader

t +61 3 9731 3228 e [email protected] w www.csiro.au

Mary Ann Augustin Research Group Leader

t +61 3 9731 3486 e [email protected] w www.csiro.au

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