Retrogradation behavior of rice flour/starch gel using response surface methodology

Effects of moisture content (40, 50, and 60%), the percent ratio of rice flour to rice starch (0, 50, and 100%), and heating-end temperature (100, 120, and 140A degrees C) on the retrogradation degree of rice flour/starch gels were investigated using a response surface methodology (RSM). The rice flour/starch samples gelatinized under different conditions were stored at 4A degrees C for 48 h, and their retrogradation enthalpy was measured by differential scanning calorimetry. The rice flour/starch gels with 50% moisture content had higher retrogradation degree than those with 40 or 60% moisture content. The retrogradation degree of rice flour/ starch gel increased as the heating-end temperature decreased. The retrogradation degree of rice flour/starch gel was higher in 1:1 mixture samples than 100% rice starch samples or 100% rice flour samples. The moisture content among three independent variables played the most critical role in the retrogradation of the rice flour/starch gel.