The present invention relates to a process for lyophilising a product (3), comprising the steps of providing a bulk product (3) loading system in the form of a bag (1), the bag (1) having an interior and an exterior defined by a flexible wall, the bag (1) further comprising a filling port (5) providing access to the interior of the bag (1), filling a product (3) having a first moisture content into the interior of the bag (1) via the filling port (5), and exposing the product (3) in the interior of the bag (1) to a lyophilisation cycle such that the moisture content of the product (3) is reduced from the first moisture content to a second, lower, moisture content.