Described is a coagulation solution suitable for causing coagulation of a collagen-containing casing of a co-extruded food product. This coagulation solution comprises a highly soluble inorganic salt. The pH of the coagulation solution is adjusted using a buffer solution. Also described is a method for coagulating a collagen-containing of a co-extruded food product. This method comprises the step of bringing the collagen casing into contact with a coagulation solution. The coagulation solution herein comprises a solution as described above.