Abstract:The effects of different polymerization degrees of persimmon tannin (DP 26/5) on the steady and dynamic rheological properties of high-methoxyl/low-methoxyl pectin (HM/LM) were investigated under various shear rates and temperatures. TA-DHR2 rheometer was used to measure the rheological properties of persimmon tannin-pectin complex. The results of static rheological tests indicated that persimmon tannin did not change the fluid type of HM/LM pectin, which was in line with Cross model, showing a shear-thinning and the pseudoplastic non-Newtonian fluid characteristic. Furthermore, the persimmon tannin-pectin composite system showed a tendency of decreasing viscosity with the increase of temperature, which was in accordance with the Arrhenius equation. Under the same temperature conditions, 0.2 % of persimmon tannin could significantly enhance the viscosity of HM/LM pectin (p < 0.001), and the viscosity of tannin-HM pectin complex was slightly higher than that of tannin-LM pectin complex. The degree of polymerization of persimmon tannin had no obvious effect on the viscosity of pectin. In addition, the results of dynamic rheological properties showed that DP26/5 persimmon tannin could shorten the HM/LM pectin gelation time and gelation temperature. Consequently, the effects of persimmon tannin on the rheological properties of pectin provided a theoretical basis for the development of functional compound ingredients of persimmon tannin-pectin.
