PASTING, THERMAL AND RHEOLOGICAL PROPERTIES OF RICE STARCH IN AQUEOUS SOLUTIONS WITH DIFFERENT CATECHINS

Addition of catechins significantly affected the properties of rice starch (RS), especially (-)-epigallocatechin gallate (EGCG). RS with EGCG exhibited the highest peak viscosity as well as maximum effects on increasing breakdown value and reducing setback value, implying that RS with EGCG have easier hydration and lower tendency toward short-term retrogradation than others. Significant changes in gelatinization enthalpies of RS in catechin solutions were not observed compared with the control. Nevertheless, retrogradation enthalpy (Delta H-r) and ratio (R%) of gelatinized RS samples with catechins were significantly decreased after 10, 20 and 30 days of storage. After 30 days of storage, RS with EGCG presented the lowest Delta H-r (5.56 J/g) and R% (52.15%). Therefore, addition of catechins can significantly delay long-term retrogradation of RS, especially EGCG. The storage modulus and loss modulus of RS with catechins were evidently reduced compared with the control at the entire stages of heating, indicating looser gel formation.