Rheological and molecular properties of chicken head gelatin as affected by combined temperature and time using warm water rendering

Physicochemical properties of gelatin extracted from chicken head at 60, 75, and 90 degrees C for 3 and 6 h, respectively were determined. Increased in extraction temperature (ETE) from 60 to 75 degrees C and extraction time (ETI) contributed to higher yield and bloom. ETE was highly correlated with yield (r = 0.954). Despite a higher yield, the gelatin bloom and viscoelastic properties began to drop at 90 degrees C. Gelatin extracted at 75 degrees C exhibited superior properties with high bloom strength of > 309 g, high in G', G", gelling (27-28 degrees C), and melting temperatures (33-34 degrees C) with great viscoelastic properties. All gelatins were of type A with alpha-chains as major protein. FTIR amide bands indicated different degrees of structural changed. Glycine was the main amino acid in G75/6 (20.69%) with total imino acid of 23.19%. Regression models were significant (p < .05), and highly fitted for yield and a* (R-2 > 0.9090%). Present findings suggest the feasibility to extract high quality gelatin from chicken head by manipulating ETE and ETI.