A method of manufacture comprising the following steps: (a) making a vent hole in a package; (b) loading product into a receptacle of the package via an opening; (c) closing the opening; (d) placing an air-permeable layer of material over the vent hole; (e) squeezing the receptacle after steps (a) through (d) have been performed to force air out the vent hole; and (f) after step (e) has been performed, sealing the package so that air cannot enter the receptacle via the vent hole. In accordance with some embodiments, the vent hole is formed in the receptacle and sealed by means of an air-impermeable patch or by joining two walls of the receptacle together. In accordance with other embodiments, the vent hole is formed in a zipper tape attached to the receptacle and various means can be used to seal the vent hole after air removal.