Chemical compositions and functional properties of gelatin from pre-cooked tuna fin

Gelatin was extracted from pre-cooked tuna caudal fin with the yield of 1.99%. Tuna fin gelatin (TFG) contained high protein content (89.54%) with hydroxyproline content of 14.12 mg g(-1). TFG comprised a lower content of high-molecular-weight cross-links and hydroxyproline content than porcine skin gelatin (PSG). However, proline content in TFG was twofold higher than that of PSG. The highest bloom strength and turbidity of TFG were observed at pH 6, while the lowest solubility was noticeable at the same pH. The bloom strength of TFG gel was lower than that of PSG gel at all pHs. TFG exhibited the lower emulsifying activity but greater emulsifying stability than PSG (P < 0.05). TFG showed poor foaming properties than PSG. The tensile strength, elongation at break, water vapour permeability of film from PSG was greater than those of TFG (P < 0.05). The study revealed that gelatin of good quality can be prepared from tuna processing discards.