Microcapsules having multiple shells and method for the preparation thereof

Abstract

Single-core and multi-core microcapsules are provided, having multiple shells, at least one of which is formed of a complex a coacervate of two components of shell materials. The complex coacervate may be the same or different for each shell. Also provided are methods for making the microcapsules.

1 . A multi-core microcapsule comprising: 
 (a) an agglomeration of primary microcapsules, each primary microcapsule comprising a core and a first shell surrounding said core;    (b) a second shell surrounding said agglomeration; and    (c) a third shell surrounding said second shell; at least one of said first, second and third shells comprising a complex coacervate.    
     
     
         2 . The multi-core microcapsule according to  claim 1 , wherein each of said first, second and third shells comprises a complex coacervate.  
     
     
         3 . The multi-core microcapsule according to  claim 1 , wherein each of said first, second and third shells comprises the same complex coacervate.  
     
     
         4 . The multi-core microcapsule according to  claim 1 , wherein at least one of said first, second and third shells comprises a complex coacervate that is different than a complex coacervate that forms one of the other shells.  
     
     
         5 . The multi-core microcapsule according to  claim 1 , wherein said complex coacervate comprises at least one polymer component selected from the group consisting of: a protein, a polyphosphate, a polysaccharide, gum arabic, alginate, chitosan, carrageenan, pectin, cellulose and cellulose derivatives.  
     
     
         6 . The multi-core microcapsule according to  claim 5 , wherein said protein is selected from the group consisting of gelatine type A, gelatine type B, soy proteins, whey proteins, milk proteins, and combinations thereof.  
     
     
         7 . The multi-core microcapsule according to  claim 1 , wherein at least one of said first, second and third shells comprises a complex coacervate between gelatine A and at least one polymer component selected from the group consisting of gelatine type B, polyphosphate, gum arabic, alginate, chitosan, carrageenan, pectin and carboxymethylcellulose.  
     
     
         8 . The multi-core microcapsule according to  claim 1 , wherein at least one of said first, second and third shells is a complex coacervate between gelatine A and polyphosphate.  
     
     
         9 . The multi-core microcapsule according to  claim 1 , further comprising at least one additional shell surrounding said third shell.  
     
     
         10 . The multi-core microcapsule according to  claim 9 , wherein said at least one additional shell surrounding said third shell comprises a complex coacervate.  
     
     
         11 . The multi-core microcapsule according to  claim 1 , wherein at least one of said first second and third shells comprises an antioxidant.  
     
     
         12 . The multi-core microcapsule according to  claim 1 , wherein at least one of said first, second and third shells comprises one or more hydrophobic components selected from the group consisting of waxes, oils, resins, and fats.  
     
     
         13 . The multi-core microcapsule according to  claim 1 , wherein at least one of said first, second and third shells comprises a complex coacervate that is cross-linked with a cross-linker.  
     
     
         14 . The multi-core microcapsule according to  claim 1 , wherein said cores comprise at least 50% of the total mass of the multi-core microcapsule.  
     
     
         15 . The multi-core microcapsule according to  claim 1 , having an exterior average diameter of from about 1 μm to about 2000 μm, and wherein said first shells have an average diameter of from about 40 nm to about 10 μm.  
     
     
         16 . A single-core microcapsule comprising: 
 (a) a core;    (b) a first shell surrounding said core; and    (c) a second shell surrounding said first shell;    at least one of said first and second shells comprising a complex coacervate.    
     
     
         17 . The single-core microcapsule according to  claim 16 , wherein said first and second shells both comprise a complex coacervate.  
     
     
         18 . The single-core microcapsule according to  claim 16 , wherein said first and second shells comprise the same complex coacervate.  
     
     
         19 . The single-core microcapsule according to  claim 16 , wherein said first and second shells comprise different complex coacervates.  
     
     
         20 . The single-core microcapsule according to  claim 16 , wherein said complex coacervate comprises at least one polymer component selected from the group consisting of: a protein, a polyphosphate, a polysaccharide, gum arabic, alginate, chitosan, carrageenan, pectin, cellulose and cellulose derivatives.  
     
     
         21 . The single-core microcapsule according to  claim 20 , wherein said protein is selected from the group consisting of gelatine type A, gelatine type B, soy proteins, whey proteins, milk proteins, and combinations thereof.  
     
     
         22 . The single-core microcapsule according to  claim 16 , wherein at least one of said first and second shells comprises a complex coacervate between gelatine A and at least one polymer component selected from the group consisting of gelatine type B, polyphosphate, gum arabic, alginate, chitosan, carrageenan, pectin and carboxymethylcellulose.  
     
     
         23 . The single-core microcapsule according to  claim 16 , wherein at least one of said first and second shells comprises a complex coacervate between gelatine A and polyphosphate.  
     
     
         24 . The single-core microcapsule according to  claim 16 , further comprising at least one additional shell surrounding said second shell.  
     
     
         25 . The single-core microcapsule according to  claim 24 , said at least one additional shell surrounding said second shell comprising a complex coacervate.  
     
     
         26 . The single-core microcapsule according to  claim 16 , wherein at least one of said first and second shells comprises an antioxidant.  
     
     
         27 . The single-core microcapsule according to  claim 16 , wherein at least one of said first and second shells comprises at least one hydrophobic component selected from the group consisting of waxes, oils, resins, and fats.  
     
     
         28 . The single-core microcapsule according to  claim 16 , wherein at least one of said first and second shells comprises a complex coacervate that is cross-linked with a cross-linker.  
     
     
         29 . The single-core microcapsule according to  claim 16 , wherein said core comprise at least 60% of the total mass of the microcapsule.  
     
     
         30 . The single-core microcapsule according to  claim 16 , having an exterior average diameter of from about 1 μm to about 2000 μm.  
     
     
         31 . A process for making a microcapsule having a plurality of shells, said process comprising: 
 (a) providing a microcapsule selected from the group consisting of: 
 (i) a multi-core microcapsule comprising: an agglomeration of primary microcapsules, each primary microcapsule comprising a core and a first shell surrounding said core; and a second shell surrounding said agglomeration; and  
 (ii) a single-core microcapsule comprising: a core; and a first shell surrounding said core;  
   (b) mixing said microcapsule with first and second polymer components of shell material in aqueous solution;    (c) adjusting at least one of pH, temperature, concentration and mixing speed to form shell material comprising said first and second polymer components, said shell material forming an additional shell enveloping said microcapsule;    wherein at least one of said first shell, said second shell and said additional shell comprises a complex coacervate.    
     
     
         32 . The process according to  claim 31 , wherein all of said shells comprise a complex coacervate.  
     
     
         33 . The process according to  claim 31  wherein, in step (b), said microcapsule is mixed with an aqueous solution comprising both said first and second polymer components of shell material.  
     
     
         34 . The process according to  claim 31  wherein, in step (b), said microcapsule is first mixed with an aqueous solution comprising said first polymer component of shell material and the resulting mixture is then mixed with a second aqueous solution comprising said second polymer component of shell material.  
     
     
         35 . The process according to  claim 31 , comprising the further steps of: 
 (d) mixing the microcapsule obtained in step (c) with third and fourth polymer components of shell material in aqueous solution;    (e) adjusting at least one of pH, temperature, concentration and mixing speed to form shell material comprising said third and fourth polymer components, said shell material forming a further shell enveloping said microcapsule.    
     
     
         36 . The process according to  claim 35 , wherein said further shell comprises a complex coacervate.  
     
     
         37 . The process according to  claim 35 , wherein said third and fourth polymer components of shell material are the same as said first and second polymer components of shell material.  
     
     
         38 . The process according to  claim 35 , wherein said third and fourth polymer components of shell material are not the same as said first and second polymer components of shell material.  
     
     
         39 . The process according to  claim 31 , wherein said first and second polymer components are selected from the group consisting of: a protein, a polyphosphate, a polysaccharide, gum arabic, alginate, chitosan, carrageenan, pectin, cellulose and cellulose derivatives.  
     
     
         40 . The process according to  claim 39 , wherein said protein is selected from the group consisting of gelatine type A, gelatine type B, soy proteins, whey proteins, milk proteins, and combinations thereof.  
     
     
         41 . The process according to  claim 31 , wherein said first polymer component comprises gelatine type A and said second polymer component comprises gelatine type B, a polyphosphate, gum arabic, alginate, chitosan, carrageenan, pectin or carboxymethylcellulose.  
     
     
         42 . The process according to  claim 31 , wherein step (b) further comprises mixing said microcapsule with an antioxidant.  
     
     
         43 . The process according to  claim 31 , comprising the further step of cross-linking said additional shell with a cross-linker.  
     
     
         44 . The process according to  claim 31 , wherein step (b) further comprises mixing said microcapsule with at least one hydrophobic component selected from the group consisting of waxes, oils, resins and fats.  
     
     
         45 . The process according to  claim 35 , comprising repeating steps (d) and (e) from 1 to 20 times to add at least one additional shell to said microcapsule.