A food freezer includes: a first housing having a first chamber arranged internally within for providing a freezing gas to a food product within the first chamber; a second housing having a second chamber arranged internally within and being in fluid communication with the first chamber for exhausting the freezing gas from the first chamber; an adjustable opening disposed at a common wall between the first chamber and the second chamber for controlling a flow of the freezing gas moving from the first chamber to the second chamber, the adjustable opening disposed to provide a flow path for the flow of the freezing gas to a region of the second chamber for exhaust from said second chamber to an area external to the first housing and second housing; and a pressure curtain comprising the exhaust and disposed at the second chamber to prevent atmosphere from the area external to the first housing and second housing from entering said housings. A related method of exhausting freezing gas is also provided.