Microencapsulation involves packaging small particles within a shell to form microparticles. Alginate is commonly used as the shell material due to its biocompatibility, non-toxicity, biodegradability, and low cost. The document describes using an air-based extrusion system to produce alginate microparticles for applications in food technology such as taste masking, controlled release, and encapsulation of probiotics. Experimental results show the air-based system produces microparticles in the 100-250 micrometer range but issues with scale-up and particle size variation need further addressing.

1. MICROINCAPSULAMENTO IN MATRICE ATTRAVERSO
SISTEMI DI ESTRUSIONE IN ARIA
Candidato
Marco Iasevoli
Matr. N06/125
Relatore
Ch.mo Prof.
Fabrizio Sarghini
ANNO ACCADEMICO 2012/2013
Matrix microencapsulation through air extrusion systems

2. Microencapsulation is the packaging of small particles of solid, liquid or
gas, also know as the core, within a secondary material, also know as the shell
or coating, to form small microparticles.
Spheres are usually classified in:
• Nanospheres (less than 100 nm)
• Microspheres (in the order of
microns)

3.  Protection of the active ingredients
 Controlled Release
 Mask unpleasant taste of certain
ingredients
 Convert liquids to solids
 Increase Shelf-life
 Increase Bioavailability

4.  GRAS Biocompatible  Good barrier properties  Cheap
Alginate in molecular terms is considered as a family of unbranched binary
copolymer of (14 linked β-D-mannuronic acid (M) and α-L-guluronic acid
(G) residues.
Why Alginate?

6. The droplet breaks off when the
gravitational force:
exceeds the surface tension induced counter
force:
leading to a droplet diameter:
MEMS 2007 - 20th IEEE International Conference on Micro Electro Mechanical Systems, 21-25 January 2007

8. Experimental Conditions
Sodium alginate
concentration (g/L)
15
Sodium Alginate flow rate
(ml/minute)
0,20
Air mass flow rate
(L/minute)
1
CaCl2 solution
Concentration (g/L)
20
CaCl2 solution mass flow
(L/minute)
1
Surface tension (mN/m) 65
Reynolds Number (Re) 1174
Weber Numbe (We) 35

10. 389 m
126 m
With Screen
(Blue Line)
Without
Screen
(Green line)

11. Geometry 1 (Blue Line) Geometry 2 (Green Line)
D [4;3] 66,4 µm
D [4;3] 241 µm

13. • Scaling-up of production is obtained by using multiple tip in parallel

14.  Air is costless
 There are only alginate
beads in hardening solution
 Easy wash with water
 No clog of device
 Large quantity of oil means increased costs.
 Oil presence in hardening solution can give
coalescence of alginate bead
 Washing oil needs specific product
 Device can clog

15. • Taste masking
• Color masking
• Flavour Stabilization
• Novel food
Technological
• Fortified foods
• Functional foods
• Drug delivery in food matrix
• Controlled release
Healty
• Studies on live cell (e.g. Probiotics)Analytical

16. Encapsulation in the food sector is becoming
even more important for its many applications.
Sodium alginate has been chosen as matrix
material because is regarded as:
•Biocompatible
•Non-toxic
•Biodegradable
•Cheap
Some issues related to the scale-up procedure
and polydispersity of the coaxial air flow
technology still need to be addressed.
Nonetheless, this technology provide to food
technologists a cheap, adaptable tool and a rapid
prototyping platform for studies on
microencapsulation through alginate.