Apparatus and methods for hydrolyzing protein-containing raw material into water soluble protein and other products. The apparatuses and methods include an optional collection or processing stage in which protein-containing raw material, such as fish or animal carcasses from food production plants, are collected and optionally processed. The raw material is then reacted with one or more enzymes to hydrolyze the protein present, after which the one or more enzymes are inactivated and the components separated. The processes and apparatuses, which can be run as a batch processes or, advantageously as a continuous processes, can yield water soluble protein, oils, bone meal and other products that have utility as food or food additives.