A packaging assembly, comprising: a) a container comprising an orifice and an opposing bottom surface, said bottom surface defining a longitudinal axis perpendicular thereto, wherein said longitudinal axis passes through said orifice; and b) a transition piece engaged to said orifice, comprising: i) a spout having a base end proximate to said orifice and an opposing pouring end having a circumferentially integral opening; and ii) a vent located adjacent to said base end, wherein said spout and said vent are in fluid communication with said orifice, and said vent has a cross-sectional area that is 1/20 to 1/3 of the cross-sectional area of said spout opening wherein said transition piece further comprises an annular channel surrounding said base end and a radially protruding shroud surrounding said channel, wherein said vent is located in said channel, wherein said shroud comprises an exterior surface, an interior surface opposing to said exterior surface, a shoulder therebetween, and a fastener surface on the underside of said exterior surface, wherein said shroud exterior surface has a set of linear indentations, and said shroud fastener surface has first sealing means configured to seal said transition piece with said container; the packaging assembly further comprising: c) a cap removably sealingly engaged to said transition piece, configured to enclose said spout, wherein said cap is in fluid communication with said spout when sealingly engaged to said transition piece, wherein said cap has an obconic shape when sealingly engaged to said transition piece, whereby said shroud interior surface has a second sealing means configured to seal said transition piece with the cap. a) a container comprising an orifice and an opposing bottom surface, said bottom surface defining a longitudinal axis perpendicular thereto, wherein said longitudinal axis passes through said orifice; and b) a transition piece engaged to said orifice, comprising: i) a spout having a base end proximate to said orifice and an opposing pouring end having a circumferentially integral opening; and ii) a vent located adjacent to said base end, wherein said spout and said vent are in fluid communication with said orifice, and said vent has a cross-sectional area that is 1/20 to 1/3 of the cross-sectional area of said spout opening wherein said transition piece further comprises an annular channel surrounding said base end and a radially protruding shroud surrounding said channel, wherein said vent is located in said channel, wherein said shroud comprises an exterior surface, an interior surface opposing to said exterior surface, a shoulder therebetween, and a fastener surface on the underside of said exterior surface, wherein said shroud exterior surface has a set of linear indentations, and said shroud fastener surface has first sealing means configured to seal said transition piece with said container; the packaging assembly further comprising: i) a spout having a base end proximate to said orifice and an opposing pouring end having a circumferentially integral opening; and ii) a vent located adjacent to said base end, wherein said spout and said vent are in fluid communication with said orifice, and said vent has a cross-sectional area that is 1/20 to 1/3 of the cross-sectional area of said spout opening wherein said transition piece further comprises an annular channel surrounding said base end and a radially protruding shroud surrounding said channel, wherein said vent is located in said channel, wherein said shroud comprises an exterior surface, an interior surface opposing to said exterior surface, a shoulder therebetween, and a fastener surface on the underside of said exterior surface, wherein said shroud exterior surface has a set of linear indentations, and said shroud fastener surface has first sealing means configured to seal said transition piece with said container; the packaging assembly further comprising: wherein said spout and said vent are in fluid communication with said orifice, and said vent has a cross-sectional area that is 1/20 to 1/3 of the cross-sectional area of said spout opening wherein said transition piece further comprises an annular channel surrounding said base end and a radially protruding shroud surrounding said channel, wherein said vent is located in said channel, wherein said shroud comprises an exterior surface, an interior surface opposing to said exterior surface, a shoulder therebetween, and a fastener surface on the underside of said exterior surface, wherein said shroud exterior surface has a set of linear indentations, and said shroud fastener surface has first sealing means configured to seal said transition piece with said container; the packaging assembly further comprising: c) a cap removably sealingly engaged to said transition piece, configured to enclose said spout, wherein said cap is in fluid communication with said spout when sealingly engaged to said transition piece, wherein said cap has an obconic shape when sealingly engaged to said transition piece, whereby said shroud interior surface has a second sealing means configured to seal said transition piece with the cap.