The optimum reaction conditions (temperature and pH) for the preparation of cross-linked (CL) corn and
wheat starches with maximum resistant starch (RS) content were investigated by using response surface
methodology (RSM). According to the preliminary results, five levels were selected for reaction temperature
(38–70 C) and pH (10–12) in the main study. RS contents of the CL corn and wheat starch samples
increased with increasing temperature and pH, and pH had a greater influence on RS content than had
temperature. The maximum RS content (with a maximum p value of 0.4%) was obtained in wheat starch
cross-linked at 38 C and pH 12. In the case of CL corn starch, the optimum condition was 70 C and pH
12. CL corn and wheat starch samples were also produced separately under the optimum conditions and
their RS contents were 80.4% and 83.9%, respectively. These results were also in agreement with the
values predicted by RSM.