Effect of sucrose and fructose on the rheological properties of gelatin derived from tilapia skin

The influence of sucrose or fructose( 5.0%,10.0%,15.0% w / w) on p H,viscosity,gelling point and melting point of fish gelatin( 1.5%,2.0%,4.0%,6.67%,w / w) was investigated in this paper.The results showed that the p H of gelatin solutions did not change with the addition of sucrose and fructose.The viscosity of gelatin( 1.5% ~6.67%w / w) were 1.7,2.2,5.0,13.3 m Pa·s respectively,which were increased binomially( R²= 0.9994) with the gelatin concentration went up.The gelling points( T_G) were 11.7,14.6,18.8,21.2 ℃ and the melting points( T_M) were 26.0,26.7,27.8,28.9 ℃ with the increase of gelatin concentration,both T_G and T_M were increased logarithmically( R²=0.9949 and 1,respectively).After the addition of sucrose or fructose,the viscosity of solutions were also increased binomially( R²= 0.9993 ~ 0.9997). The concentration effect of sucrose on T_G and T_M of gelatin was stronger than fructose.A nearly linear relation( R²= 0.9772 ~0.9886) was found between the logarithm of the gelatin concentration and the reciprocal absolute temperature of melting or gelling,which was in line with Eldridge- Ferry model.