For the existence of low protein extraction yield, high impurity content, poor functional properties and flavor in processing and utilization of aquatic protein, fish protein isolates (FPI) was prepared from Tilapia muscle and by-products by pH-shifting in this study. Fish muscle proteins were extracted at either acidic (pH<3.5) or alkaline (pH>10.5) at low temperature to obtain the maximum solubility and remove fat and insoluble impurities via high-speed centrifugation followed by the recovery of precipita...