Ten milliliter of a 40 g defatted blended head and gut of threadfin bream (DBHG) per liter was
hydrolysed with immobilized alcalase. The optimum hydrolysis conditions that produced fish protein
hydrolysates with the highest emulsion capacity were found to be hydrolysis with 0.2 g immobilized
alcalase at 60°C pH 9.0 for 40 min. The highest emulsion capacity of fish protein hydrolysate was
189.22 ml of oil per g of protein at 35.82% degree of hydrolysis (DH). Repeated use of immobilized
alcalase decreased %DH. When immobilized alcalase was used four times repeatedly, the DH of fish
protein hydrolysate decreased from 35.82% to 26.16%, 20.07% and 20.12% respectively.
Rehydrolyzing the solid residues increased the protein extraction yield. When rehydrolysed DBHG
three times, the total extracted protein content was 86.39% of the initial protein content