Embedding and encapsulation of controlled release particles

• US 6,190,591 B1
• Filed: 05/17/1999
• Issued: 02/20/2001
• Est. Priority Date: 10/28/1996
• Status: Expired due to Term

• Current Assignee: General Mills Incorporated
• Original Assignee: General Mills Incorporated
• Inventors: van Lengerich, Bernhard H.
• Primary Examiner(s): Silbaugh, Jan H.
• Assistant Examiner(s): Eashoo, Mark
• Application Number:
  US09/269,763
• Time in Patent Office: 645 Days
• Field of Search: 264/141, 264/142, 264/171.1, 264/211, 424/408, 424/489, 424/491
• US Class Current: 264/141
• CPC Class Codes: A23L 27/72 Encapsulation
• CPC Class Codes: A23L 29/212 Starch; Modified starch; Starch derivatives, e.g. esters or ethers containing starch hydrolysates, e.g. dextrin, A23L29/30
• CPC Class Codes: A23P 10/25 Agglomeration or granulation by extrusion or by pressing, e.g. through small holes, through sieves or between surfaces
• CPC Class Codes: A23P 10/30 Encapsulation of particles, e.g. foodstuff additives
• CPC Class Codes: A61K 9/1652 Polysaccharides, e.g. alginate, cellulose derivatives; Cyclodextrin homeopathic globules A61K9/1623
• CPC Class Codes: A61K 9/1694 resulting in granules or microspheres of the matrix type containing more than 5% of excipient
• CPC Class Codes: B01J 13/02 Making microcapsules or microballoons for medical preparations A61K9/50
• CPC Class Codes: B01J 13/04 by physical processes, e.g. drying, spraying
• CPC Class Codes: B29B 7/421 with screw and additionally other mixing elements on the same shaft, e.g. paddles, discs, bearings, rotor blades of the Banbury type
• CPC Class Codes: B29B 7/482 provided with screw parts in addition to other mixing parts, e.g. paddles, gears, discs
• CPC Class Codes: B29B 7/72 Measuring, controlling or regulating
• CPC Class Codes: B29B 7/823 Temperature control
• CPC Class Codes: B29B 7/826 Apparatus therefor
• CPC Class Codes: B29B 7/86 for working at sub- or superatmospheric pressure B01F33/70 takes precedence
• CPC Class Codes: B29B 7/94 Liquid charges
• CPC Class Codes: B29B 9/06 in the form of filamentary material, e.g. combined with extrusion
• CPC Class Codes: B29B 9/12 characterised by structure or composition
• CPC Class Codes: B29C 2793/009 after shaping
• CPC Class Codes: B29C 2948/92019 Pressure
• CPC Class Codes: B29C 2948/92047 Energy, power, electric current or voltage
• CPC Class Codes: B29C 2948/92095 : Angular velocity
• CPC Class Codes: B29C 2948/92209 : Temperature
• CPC Class Codes: B29C 2948/92314 : Particular value claimed
• CPC Class Codes: B29C 2948/9238 : Feeding, melting, plasticising or pumping zones, e.g. the melt itself
• CPC Class Codes: B29C 2948/924 : Barrel or housing
• CPC Class Codes: B29C 2948/92514 : Pressure
• CPC Class Codes: B29C 2948/9258 : Velocity
• CPC Class Codes: B29C 2948/9259 : Angular velocity
• CPC Class Codes: B29C 2948/926 : Flow or feed rate
• CPC Class Codes: B29C 2948/92657 : Volume or quantity
• CPC Class Codes: B29C 2948/92666 : Distortion, shrinkage, dilatation, swell or warpage
• CPC Class Codes: B29C 2948/92676 : Weight
• CPC Class Codes: B29C 2948/92695 : Viscosity; Melt flow index [MFI]; Molecular weight
• CPC Class Codes: B29C 2948/92704 : Temperature
• CPC Class Codes: B29C 2948/92723 : Content, e.g. percentage of humidity, volatiles, contaminants or degassing
• CPC Class Codes: B29C 2948/92809 : Particular value claimed
• CPC Class Codes: B29C 2948/92828 : Raw material handling or dosing, e.g. active hopper or feeding device
• CPC Class Codes: B29C 2948/92838 : Raw material pre-treatment, e.g. drying or cleaning
• CPC Class Codes: B29C 2948/92847 : Inserts
• CPC Class Codes: B29C 2948/92876 : Feeding, melting, plasticising or pumping zones, e.g. the melt itself
• CPC Class Codes: B29C 2948/92885 : Screw or gear
• CPC Class Codes: B29C 2948/92895 : Barrel or housing
• CPC Class Codes: B29C 2948/92933 : Conveying, transporting or storage of articles
• CPC Class Codes: B29C 48/022 : characterised by the choice of material
• CPC Class Codes: B29C 48/04 : Particle-shaped making granules B29B9/00
• CPC Class Codes: B29C 48/05 : Filamentary, e.g. strands
• CPC Class Codes: B29C 48/08 : flexible, e.g. films
• CPC Class Codes: B29C 48/29 : in liquid form
• CPC Class Codes: B29C 48/345 : Extrusion nozzles comprising two or more adjacently arranged ports, for simultaneously extruding multiple strands, e.g. for pelletising
• CPC Class Codes: B29C 48/40 : using two or more parallel screws or at least two parallel non-intermeshing screws, e.g. twin screw extruders
• CPC Class Codes: B29C 48/92 : Measuring, controlling or regulating
• CPC Class Codes: B29K 2003/00 : Use of starch or derivatives as moulding material
• CPC Class Codes: B29K 2105/0005 : containing compounding ingredients releasing, lubricating or separating agents B29C33/56, fibers B29K2105/08, B29K2105/12; fillers B29K2105/16, recycled material B29K2105/26
• CPC Class Codes: Y02A 50/30 : Against vector-borne diseases, e.g. mosquito-borne, fly-borne, tick-borne or waterborne diseases whose impact is exacerbated by climate change

Abstract

Controlled release, discrete, solid particles which contain an encapsulated and/or embedded component such as a heat sensitive destruction or readily oxidizable pharnaceutically, biologically, or nutritionally active component are continuously produced without substantial destruction of the matrix or encapsulant. A release-rate controlling component is incorporated into the matrix to control the rate of release the encapsulant from the particles. the additional component may be a hydrophobic component or a high water binding capacity component for extending the release time. The plasticizable matrix material, such as starch, is admixed with at least one plasticizer, such as water, and at least one release-rate controlling component under low shear mixing conditions to plasticize the plasticizable material without substantially destroying the at least one plasticizable material and to obtain a substantially homogeneous plasticized mass. The plasticizer content is substantially reduced and the temperature of the plasticized mass is substantially reduced prior to admixing the plasticized mass with the encapsulant to avoid substantial destruction of the encapsulant and to obtain a formable, extrudable mixture. The mixture is extruded though a die without substantial or essentially no expansion and cut into discrete, relatively dense particles. Release properties may also be controlled by precoating the encapsulant and/or coating the extruded particles with a film-forming component.

Claims

1. A method for continuously encapsulating or embedding a component in a matrix comprising:

a. admixing at least one plasticizable matrix material with at least one plasticizer and at least one component for controlling the rate of release of an encapsulant, said admixing being under low shear conditions to plasticize the plasticizable material without substantially destroying the at least one plasticizable material and to obtain a substantially homogeneous plasticized mass,

b. reducing the plasticizer content of said plasticized mass,

c. reducing the temperature of the plasticized mass to obtain a cooled, plasticized mass,

d. admixing at least one encapsulant with said cooled, plasticized mass to obtain a formable mixture, said admixing being under low shear mixing conditions at a plasticized mass temperature which avoids substantial thermal destruction of said at least one encapsulant,

e. extruding said formable mixture through a die to obtain an extrudate, and

f. cutting said extrudate into pieces.

2. A method as claimed in claim 1 wherein said plasticizable material and said plasticizer are admixed and heated above the melt or glass transition temperature of the plasticizable material and then admixed with said at least one release-rate controlling component.

3. A method as claimed in claim 1 wherein said plasticizable material, said plasticizer, and said at least one release-rate controlling component are admixed and then heated above the melt or glass transition temperature of the plasticizable material.

4. A method as claimed in claim 1 wherein said encapsulant is coated with a film-forming material prior to admixing with said cooled, plasticized mass.

5. A method as claimed in claim 4 wherein said pieces are coated with a film-forming material.

6. A method as claimed in claim 1 wherein said pieces are coated with a film-forming material.

7. A method as claimed in claim 1 wherein said plasticizable matrix material comprises starch, said plasticizer comprises water, and said admixing to obtain a substantially homogenous plasticized mass is conducted with heating to at least substantially gelatinize said starch.

8. A method as claimed in claim 7 wherein said at least one release-rate controlling component is a hydrophobic component.

9. A method as claimed in claim 8 wherein said hydrophobic component is at least one member selected from the group consisting of fats, oils, waxes, fatty acids, emulsifiers, polyolefms, polyurethanes, polyvinylchloride, paraffins, polyvinyl acetates, and modified starches.

10. A method as claimed in claim 7 wherein said at least one release-rate controlling component is a high water binding capacity component.

11. A method as claimed in claim 10 wherein said high water binding capacity component is selected from the group consisting of proteins, and hydrocolloids.

12. A method as claimed in claim 7 wherein the amount of said at least one release-rate controlling agent is from about 10% by weight to about 35% by weight, based upon the weight of said starch.

13. A method as claimed in claim 12 wherein the starch content of said pieces is at least about 40% by weight, based upon the weight of said pieces.

14. A method as claimed in claim 7 wherein the water content of the plasticized mass is reduced by at least about 10% by weight.

15. A method as claimed in claim 7 wherein said encapsulant is admixed with distributive mixing screw sections for a total length of about 3-10 l/d to sufficiently admix, distribute and embed the added ingredients into the matrix.

16. A method as claimed in claim 1 wherein said plasticizable matrix material comprises a pregelatinized starch or durum wheat flour and said plasticizer is water.

17. A method as claimed in claim 1 wherein the extrudate is separated into individual pieces using a cutter, pelletizer, rotating knives or counterrotating forming drums that have indented molds to obtain pieces having a length to diameter ratio of between 0.5 and 10.

18. A method as claimed in claim 1, wherein the formable mixture is extruded through a die having multiple apertures, at a rate of extrudate per die area of less than about 5 kg/h per mm².

19. A method as claimed in claim 18, wherein the rate of extrudate per die area is less than 3 kg/h per mm².

20. A method as claimed in claim 19, wherein the rate of extrudate per die area is less than about 0.5 kg/h per mm².

21. A method as claimed in claim 1, wherein the diameter of the apertures is from about 0.5 mm to about 5 mm.

22. A method as claimed in claim 21, wherein the diameter of the apertures is from about 0.5 mm to about 1 mm.

23. A method for continuously encapsulating or embedding a component in a matrix comprising:

a. admixing at least one plasticizable matrix material with at least one plasticizer, and at least one component for controlling the rate of release of an encapsulant, said admixing being under low shear conditions to plasticize the plasticizable material without substantially destroying the at least one plasticizable material and to obtain a substantially homogeneous plasticized mass;

b. admixing at least one encapsulant with said plasticized mass to obtain a formable mixture, said admixing being under low shear and low temperature conditions to avoid substantial thermal destruction of said at least one encapsulant;

c. forming said formable mixture into pieces by extruding the formable mixture through a die having multiple apertures at a rate of extruded mixture per apertures area of less than about 5 kg/h per mm².

24. A method as claimed in claim 23, wherein the diameter of the apertures is from about 0.5 mm to about 5 mm.

25. A method for continuously encapsulating or embedding a component in a matrix comprising:

a. admixing at least one plasticizable matrix material with at least one plasticizer, and at least one component for controlling the rate of release of an encapsulant, said admixing being under low shear conditions to plasticize the plasticizable material without substantially destroying the at least one plasticizable material and without cooking or gelatinizing the at least one plasticizable material to obtain a substantially homogeneous plasticized mass;

b. admixing at least one encapsulant with said plasticized mass to obtain a formable mixture, said admixing being under low shear and low temperature conditions to avoid substantial thermal destruction of said at least one encapsulant;

c. extruding said formable mixture through a die to obtain an extrudate, and

d. cutting said extrudate into pieces.

26. A method as claimed in claim 25, wherein said plasticizable matrix material comprises durum wheat.