The disclosure relates to an aseptic bag (1) for separating off liquid. The bag comprises a tight outer bag (2) and a perforated inner bag (3). Each bag (2, 3) consists of two parts (4, 5, 6, 7). In the first bag part (4, 6) of the outer bag (2) and the inner bag (3), there is disposed an inlet device (12) and, in the second bag part (5, 7), there are disposed closure means (13) which may rigidly engage with the inlet device (12). In addition, there is provided in the first part (4) of the outer bag (2) an outlet device (18) and corresponding closure means (19) in its second part (5). An inlet valve (14) is connected to the inlet device (12) and an outlet valve (22) is connected to the outlet device (18). The product, solid particles mixed with a carrier liquid, is filled through the inlet valve (14) into the aseptic bag (1). The solid particles will then remain in the inner bag (3), while the liquid will continue through the perforations in the bag (3) and be separated through the outlet valve (22).