Method for recovering proteins from waste water discharged during process of producing fish meat processed product

1. A method for recovering water-soluble proteins from fish paste leaching waste water or stick water, the method consisting of:

adjusting the pH of fish paste leaching waste water or stick water to 4.5-5.5 via a one-stage pH adjustment to insolubilize water-soluble proteins;

heating the insolubilized proteins to 50° C. to 60° C. to cause the proteins to flocculate so as to form flocs; and

subjecting the flocs to solid-liquid separation using a decanter centrifuge during heating; and recovering proteins in the form of solid content.

2. The method according to claim 1 , wherein the ash content in matter comprising recovered proteins accounts for 3% by weight or less of matter comprising recovered proteins after drying.

3. A method for producing fish paste, comprising adding water-soluble proteins to a fish paste, wherein the water-soluble proteins have been obtained by a process consisting of

adjusting the pH of fish paste leaching waste water or stick water to 4.5-5.5 via a one-stage pH adjustment to insolubilize water-soluble proteins;

heating the insolubilized proteins to 50° C. to 60° C. to cause the proteins to flocculate so as to form flocs; and

subjecting the flocs to solid-liquid separation using a decanter centrifuge during heating; and recovering proteins in the form of solid content.

4. A method for producing fishmeal, comprising adding water-soluble proteins to a fishmeal, wherein the water-soluble proteins have been obtained by a process consisting of

adjusting the pH of fish paste leaching waste water or stick water to 4.5-5.5 via a one-stage pH adjustment to insolubilize water-soluble proteins;

heating the insolubilized proteins to 50° C. to 60° C. to cause the proteins to flocculate so as to form flocs; and

subjecting the flocs to solid-liquid separation using a decanter centrifuge during heating; and recovering proteins in the form of solid content.