A method of reducing a pathogenic microorganism population in a powdered nutritional food composition is described herein. The powdered nutritional food composition includes a fat, a protein, and a carbohydrate. The method includes forming an emulsion of the powdered nutritional food composition and extruding the emulsified powdered nutritional food composition at a temperature of less than about 100oC. The method produces at least a 5 log reduction in the pathogenic microorganism population in the extruded powdered nutritional food composition. The extruded powdered nutritional food composition has a water activity level of about 0.3 to about 0.95.
