A packaging apparatus for forming a plurality of sealed packages filled with a pourable product comprising: - a conveying device adapted to advance a web of packaging material along an advancement path; - an isolation chamber separating an inner environment containing a sterile gas from an outer environment; - a tube forming and sealing device being at least partially arranged within the isolation chamber and being adapted to form and longitudinally seal a tube from the, in use, advancing web of packaging material; wherein the conveying device is also adapted to advance the tube along a tube advancement path; - a delimiting element arranged, in use, within the tube and designed to divide the tube in a first space being in fluidic connection with the inner environment and a second space being arranged downstream of the first space along the tube advancement path; - a filling device adapted to direct, in use, a pourable product into the second space; - a sterile gas supply device configured to generate and to pressurize a sterile gas and to divide the generated and pressurized sterile gas at least into a first flow of the sterile gas and at least a second flow of the sterile gas; wherein the sterile gas supply device is also configured to direct the first flow of the sterile gas into the isolation chamber and the second flow of the sterile gas into the second space; characterized in that the sterile gas supply device comprises a first gas feeding conduit, fluidically connected with inner environment and configured to direct, in use, the first flow of sterile gas into isolation chamber, and a second gas feeding conduit configured to direct, in use, the second flow of sterile gas into the second space wherein the sterile gas supply device is furthermore configured to control the first flow of sterile gas and the second flow of sterile gas such that the gas pressure within the second space is higher than the gas pressure within the isolation chamber. - a conveying device adapted to advance a web of packaging material along an advancement path; - an isolation chamber separating an inner environment containing a sterile gas from an outer environment; - a tube forming and sealing device being at least partially arranged within the isolation chamber and being adapted to form and longitudinally seal a tube from the, in use, advancing web of packaging material; wherein the conveying device is also adapted to advance the tube along a tube advancement path; - a delimiting element arranged, in use, within the tube and designed to divide the tube in a first space being in fluidic connection with the inner environment and a second space being arranged downstream of the first space along the tube advancement path; - a filling device adapted to direct, in use, a pourable product into the second space; - a sterile gas supply device configured to generate and to pressurize a sterile gas and to divide the generated and pressurized sterile gas at least into a first flow of the sterile gas and at least a second flow of the sterile gas; wherein the sterile gas supply device is also configured to direct the first flow of the sterile gas into the isolation chamber and the second flow of the sterile gas into the second space; characterized in that the sterile gas supply device comprises a first gas feeding conduit, fluidically connected with inner environment and configured to direct, in use, the first flow of sterile gas into isolation chamber, and a second gas feeding conduit configured to direct, in use, the second flow of sterile gas into the second space wherein the sterile gas supply device is furthermore configured to control the first flow of sterile gas and the second flow of sterile gas such that the gas pressure within the second space is higher than the gas pressure within the isolation chamber. wherein the sterile gas supply device is also configured to direct the first flow of the sterile gas into the isolation chamber and the second flow of the sterile gas into the second space; characterized in that the sterile gas supply device comprises a first gas feeding conduit, fluidically connected with inner environment and configured to direct, in use, the first flow of sterile gas into isolation chamber, and a second gas feeding conduit configured to direct, in use, the second flow of sterile gas into the second space wherein the sterile gas supply device is furthermore configured to control the first flow of sterile gas and the second flow of sterile gas such that the gas pressure within the second space is higher than the gas pressure within the isolation chamber.