Optimal Conditions to Remove Chemical Hazards in Fish Protein Isolates from Tilapia Frame Using Response Surface Methodology

Response surface methodology (RSM) was employed to maximize the removal of phospholipids (PLs) and other chemical hazards in tilapia protein isolates made from tilapia frame (TF). CaCl₂ and the ratio of water to minced tilapia frame (W:TF) were the significant variables affecting PLs reduction. The optimum condition for maximal PLs reduction (90.0%) was: 10.25 mM CaCl₂ and a W:TF of 7.8:1, while other variables were fixed at 5 mM citric acid, 60 min incubation, pH 11, and centrifugal speed of 8,000 × g. At these conditions, the great reduction of lipids (93.9%), Hg (97.6%), and As (95.5%), as well as 86.1% of protein recovery, were obtained. Protein isolates with significantly reduced chemical hazards and lipids were successfully prepared from tilapia frames using the alkaline extraction assisted with CaCl₂ and citric acid.