Abstract: By using citric acid and malic acid, starch citrate and starch malate were prepared successfully. After determination of resistant starch(RS), it was found that the highest yields of resistant starch were above 90%. FT-IR revealed that there was an absorption valley at 1730.9～1733.6cm-1 that was characteristic of ester group. By FT-IR, it was found that there was an absorption valley at 1730.9～1733.6cm-1. In comparison of citric acid with malic acid, it was obvious that citric acid was much easier to react with starch than with malic acid. The reason is that 170℃ was higher than 140℃ while RS yields reached 93%. Phosphorylated distarch phosphodiester was as white as native cornstarch and starch granules still kept original shape. But they gathered together. After boiling in water, they kept original state and did not gelatinise. Using DSC, it was noticed that the endothermal peak of distarch phosphodiester centred at 105℃, indicating that boiling in water could not make distarch phosphodiester gelatinise. The reason may be that cross-linking tied starch granules tightly so that it avoided to be expanded and destroyed. By FT-IR, no absorption valley was found at 1300～1250cm-1 that was the characteristic of“ P=O”group, therefore only a small a mount of starch molecules joined esterification reaction. The similar phenomenon had been found by some other researchers. These results were in agreement with their results. RS content of the sample was more than 70%. Without any special additive, the same bread comparable to the control was made successfully. It was noteworthy that the amount of water added was a little more than that of the control. It is important that to note after adding cross-linked starch we do hardly find any obvious change in color, odor, flavor, mouth feel and texture of breads. Starch malate has not been reported so far. Furthermore, RS contents of our modified starches are up to 93%.

Key words: starch, polysaccharide, esterification, resistant starch(RS)