Abstract: The rate of starch digestibility and the enzymatic resistivity was evaluated in some cross-linked tapioca starch in terms of in vitro model and the effect of cross-linking on the reactivity of tapioca starch by enzyme were discussed. The results showed that the starch digestion rate by salivary α-amylase is decreased as the degree of cross-linking increased. High cross- linking degree of starch granules decreased the digestion rate. However, low cross-linked reaction increased the rate of starch granule but had little effect on its pastes. Moreover, the influence of cross-linked with POCl3 on the enzymatic resistivity was revealed by using the Megazyme total starch assay kit. The decrease in enzyme hydrolysis after cross-linking was higher as cross-linking degree increased and the amount of total resistant starch increased. These decreases were higher in high cross-linked tapioca starch where granular structure became non-crystallized. But for the retrograded cross-linked tapioca starch, the percentage of enzyme hydrolysis increased with the increase of cross-linking degree until 1.71×10-2 and then decreased. It is concluded that the sensitivity of starch granules to enzyme and their reactivity can be regulated by controlling the degree of cross-linking(DC), which is likely to affect the nutritional characteristics of tapioca starch.

Key words:  , cross-linked starch； digestibility； resistant starch；