Described herein is a method of forming individual tubes or sachets containing fluent material, and a packaging machine for doing so, are described. The side of the foil which will be in contact with the fluent material when the package is formed is exposed to plasma in mist or aerosol form as the tube or sachet is formed from a strip of laminate material (1), which is folded about a former (2) into a closed tube or sachet which passes over the open end of a dispensing tube (3) from which the fluent material is dispensed. A mist of plasma is injected into the interior of the material tube as it is formed, extracted from the area once it has passed over the interior walls of the laminate tube.