Water-based edible inks for ink-jet printing on confectionery

Abstract

Non-pigmented, water-based inks are disclosed which are compatible with industrial piezojet printheads and which can be used to form high resolution images on edible substrates, including sugar shell confectionery polished with a hydrophobic wax polish. The ink comprises a hydrolyzable polysaccharide adhesive agent, such as tapioca dextrin or gum arabic, which enhances the compatibility of the ink for hydrophobic surfaces.

1 . A non-pigmented water-based ink-jettable edible ink comprising:
 (a) 50.0 to 85.0 wt. % water;   (b) 7.0 to 35.0 wt. % organic solvent selected from the group consisting of a C1 to C6 alcohol, propylene glycol, and mixtures thereof;   (c) 0.5 to 15.0 wt. % of a non-pigmented edible colorant selected from the group consisting of FD&C dyes, natural colorants, and synthetic colorants, wherein the colorant is soluble in water or water-alcohol mixtures;   (d) 2.0 to 40.0 wt. % binder; and   (e) 1.5 to 8.0 wt. % of a dextrin or gum adhesive agent,   wherein the ink is substantially free of conductivity-enhancing salts and has a conductivity lower than 700 micro Siemens, a viscosity of 5 to 20 centipoise, and a surface tension of less than 50 dynes per centimeter when applied to an edible substrate.   
     
     
         2 . An edible ink of  claim 1  which is ink-jettable with a piezojet drop-on-demand ink-jet printer to form an image having a resolution greater than 150 dots per inch. 
     
     
         3 . An edible ink of  claim 1  comprising 50.0 to 75.0 wt. % water. 
     
     
         4 . An edible ink of  claim 1  comprising 10.0 to 30.0 wt. % organic solvent. 
     
     
         5 . An edible ink of  claim 1  in which the organic solvent is ethanol, isopropanol, butanol, propylene glycol, or mixtures thereof. 
     
     
         6 . An edible ink of  claim 1  comprising 2.0 to 6.0 wt. % dextrin or gum adhesive agent. 
     
     
         7 . An edible ink of  claim 1  in which the dextrin is tapioca dextrin or the gum is gum arabic. 
     
     
         8 . An edible ink of  claim 1  in which the binder is a shellac-based film former, polyvinylpyrrolidone, or a mixture thereof. 
     
     
         9 . An edible ink of  claim 8  comprising 8.0 to 25.0 wt. % shellac-based film former and 1.5 to 12.0 wt. % polyvinylpyrrolidone. 
     
     
         10 . An edible ink of  claim 1 , comprising:
 (a) 50.0 to 75.0 wt. % water;   (b) 10.0 to 30.0 wt. % organic solvent;   (c) 0.5 to 15.0 wt. % of a non-pigmented edible colorant selected from the group consisting of FD&C dyes, natural colorants, and synthetic colorants, wherein the colorant is soluble in water or water-alcohol mixtures;   (d) 2.0 to 40.0 wt. % binder comprising, with respect to the ink, 8.0 to 25 wt. % shellac-based film former and 1.5 to 12.0 wt. % polyvinylpyrrolidone; and   (e) 2.0 to 6.0 wt. % dextrin or gum adhesive agent.   
     
     
         11 . An edible ink of  claim 1  having an intrinsic viscosity of 23 to 30 cubic centimeters per gram. 
     
     
         12 . A method for ink-jet printing images on confectionery pieces, comprising:
 (a) positioning a confectionery piece having a hydrophobic surface proximate to a print station comprising a piezojet drop-on-demand ink-jet printhead having at least one ink reservoir;   (b) supplying to the ink reservoir a non-pigmented water-based ink-jettable edible ink comprising:
 (i) 50.0 to 85.0 wt. % water; 
 (ii) 7.0 to 35.0 wt. % organic solvent selected from the group consisting of a C1 to C6 alcohol, propylene glycol, and mixtures thereof; 
 (iii) 0.5 to 15.0 wt. % of a non-pigmented edible colorant selected from the group consisting of FD&C dyes, natural colorants, and synthetic colorants, wherein the colorant is soluble in water or water-alcohol mixtures; 
 (iv) 2.0 to 40.0 wt. % binder; and 
 (v) 1.5 to 8.0 wt. % of a dextrin or gum adhesive agent, 
 wherein the ink is substantially free of conductivity-enhancing salts and has a conductivity lower than 700 micro Siemens; and 
   (c) printing an image having a resolution greater than 150 dots per inch on the hydrophobic surface with the printhead.   
     
     
         13 . A method according to  claim 12 , in which positioning the confectionery piece comprises serially conveying a plurality of confectionery pieces on a conveyor past the printhead. 
     
     
         14 . A method according to  claim 12 , in which the printhead has multiple reservoirs, and the method further comprises:
 (a) supplying a pigmented edible white ink to one of the multiple reservoirs; and   (b) supplying the non-pigmented water-based ink-jettable edible ink to another reservoir.