The invention provides a method for extracting collagen from cold water fish byproducts, and relates to the technical field of
food processing. The extraction method provided by the invention comprises the following steps: sequentially carrying out pretreatment,
deep eutectic solvent synergistic ultrasonic extraction treatment, directional controllable subcritical water technology extraction treatment, separation and
drying on cold water fish byproducts to obtain collagen, and further preparing
collagen peptide from part of collagen. According to the method disclosed by the invention, the acid-soluble collagen is efficiently extracted at low temperature under the assistance of ultrasonic
waves by virtue of the deep-eutectic
solvent, and then the collagen which is not dissolved out by the deep-eutectic
solvent and is tightly crosslinked in the
skin residues is directionally hydrolyzed by virtue of the subcritical water, so that graded accurate extraction is realized, and the total extraction rate is increased to 90% or above; meanwhile, through two-step sequential extraction, nearly complete utilization of the raw materials is realized in the whole process, and a series of products from complete collagen to
collagen peptide can be obtained through parameter regulation and control, so that the additional value and comprehensive utilization efficiency of cold water
fish processing byproducts are remarkably improved.