Effect of tea polyphenols on the retrogradation of rice starch

The effect of tea polyphenols (TPLs) on the retrogradation of rice starch (RS) was investigated. TPLs-fortified RS exhibited retarding of retrogradation as assessed by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The analytic samples had a water-RS/TPLs ratio of 2:1. RS/TPLs mixing ratios were 5/0, 5/0.3, 5/0.5, 5/0.7, and 5/1 (w/w) that equated with RS containing 0%, 6%, 10%, 14%, and 20% TPLs (based on RS weight), respectively. In the DSC analysis, the temperature and enthalpy of starch gelatinization obviously decreased as the polyphenols level increased. After storage at 4 degrees C, retrogradation enthalpy for RS with 10%, 14%, and 20% TPLs did not appear until storage of 20 days. After 10 days of storage at 20% TPLs had almost no recrystallization of the retrogradation. The RS gel with 10% age at 4 degrees C, overall results demonstrate that the marked inhibitory effect of TPLs on the retrogradation of RS. (c) 2008 Elsevier Ltd. All rights reserved.