Highly-porous mannitol particle production using a new templating approach

A new method has been successfully developed to create highly-porous powder templates through the spray drying of mannitol, using citric acid as the templating agent and then removing the citric acid by ethanol washing of the spray-dried powders. It has been demonstrated that textural properties, such as the surface area and the pore volume of the resultant mannitol, can be tuned by varying the concentrations of citric acid, whey protein isolate (WPI), and Gum Arabic. The resulting powder structure is a mannitol network with significant porosity and high surface area of 8.0 ± 0.4 m2/g and total pore volume of 0.075 ml/g. The scanning electron microscope micrographs were consistent with the Brunauer-Emmett-Teller (BET) surface area measurements. It has been found that higher concentrations of WPI, more than 0.5% w/w, have a detrimental effect on the porosity of the spray-dried powders from the solutions of mannitol/WPI with 2% (w/w) citric acid. For Gum Arabic, more than 1% (w/w) Gum Arabic causes lower porosities due to the lower citric acid removal by ethanol washing. The results of this study allow excipient powders to be produced with high specific surface areas.