Provided are devices comprising immobilised lipases useful for preparing a nutritional formula comprising monoglycerides and/or free fatty acids via exposing a composition comprising long-chain polyunsaturated fatty acids to the interior of a device. In one embodiment the device comprises a rod-like extension having a distal end and a proximal end； a pocket having an interior region defined by one or more walls, wherein the pocket is located at a distal region of the rod-like extension； a lipase immobilized by covalent binding to a structure contained within the pocket, wherein the one or more walls are permeable to the nutritional composition but not to the structure so that the nutritional composition is exposed to the lipase when the nutritional composition enters the interior region. Further provided are related nutritional formulas and their use for providing nutrition, for improving fat absorption, for improving cognitive ability, for preventing chronic lung disease, and for reducing the length of time a patient requires total parenteral nutrition.
