Controlled-atmosphere product packaging and associated method of use

A packaging (1) for a product (2) including a container (5) made from a single-use cellulose-based material defining a product (2) receiving volume, said container (5) being adapted to change by folding (F) from a first configuration in the form of a flat plate to a second configuration in which the folded plate defines a product (2) receiving volume, the folded plate being held in shape in the second configuration, when the product (2) is in place in the container (5), by attaching (F1) a sealing film (3) welded to the free upper end of the container (5), said end extending outwards from the walls (11) of the container (5) and forming a rim (14), the packaging (1) also comprising another, reusable part formed by a mold (7) of dimensions and shape corresponding to those of the container (5) when the latter is in the second configuration, characterized in that the packaging (1) comprises a single-use, gas-tight, product (2) receiving bag (15) adapted to be positioned in the container (5) before the sealing film (3) is put in place.