Production of aqueous shellac dispersions by high pressure homogenisation

The use of shellac for coating purposes in pharmacy, food and nutriceutical industry generally involves the use of organic solvents. An aqueous shella c dispersion has been developed by applying high pressure homogenisation. S hellac was dissolved in alkaline solution, precipitated by HCl addition and the obtained suspension homogenised at 1500 bar applying 20 cycles. The vo lume diameter 50% was 2 mum, a distinct fraction of particles was in the na nometer range. This surfactant-free shellac dispersion with 20% solid conte nt proved to be physically stable and showed good film forming properties. (C) 2001 Elsevier Science B.V. All rights reserved.