Interface device, coloring agent and method for imparting color to food material

An interface device assembled with:

• (i) a pastry bag into which frosting is loaded for application onto food items;
• (ii) a two-piece pastry bag coupler and collar;
• and (iii) a treatment nozzle which (a) is adapted to be attached to said pastry bag by said coupler and said collar;
• and (b) is configured to apply a shape to the frosting as said frosting is extruded through said treatment nozzle;
• wherein said interface device is interposed between said coupler and said collar, and wherein said interface device comprises an annular shaped coloring means configured to apply a color to an outside of the frosting as the frosting is extruded through said interface device;
• said interface device comprising:
• a body having:
• (a) a first end;
• (b) a second, distal end;
• (c) an internal wall disposed between said first and second ends;
• (d) the coloring means to be placed on said internal wall, interposed between said coupler and collar and locked in place there-between;
• (e) first means at said first end wherein said coupler attaches said first end to said pastry bag by said first means;
• and
• (f) second means at said second end wherein said collar attaches said second end to said nozzle by said second means.