A recipient for containing moist substrate, which recipient includes a flexible polymer wall having an outer surface and at least one gas exchanging membrane, which gas exchanging membrane is hermetically sealed to the outer surface of the flexible polymer wall along a sealing line. The sealing line defining a hermetically sealed area of the flexible polymer wall. The flexible polymer wall includes at least one aperture, being provided in this hermetically sealed area of the flexible polymer wall. The recipient further includes a mechanism for creating an air chamber circumscribed by the hermetically sealed area and the gas exchanging membrane, for preventing moist substrate to contact the gas exchanging membrane when the recipient is filled with moist substrate.