Influence of chemical modification level of starch on flow properties of gelatinized phosphate cross-linked and acetylated waxy corn starch suspensions

Waxy corn starch was modified doubly by acetylation and cross-linking with acetic vinyl and phosphorus oxychloride (POCl3). Degree of cross-linking was varied using 0.008similar to0.02% phosphorus oxychloride, and acetylated substitution was adjusted to the same degree on all starch samples. Flow properties of these starch suspensions were determined by using a capillary tube viscometer. Flow parameters of these starch suspensions were markedly changed over 1.21 x 10(-4)% (w/w) of the phosphorus content. Logarithmic value of the consistency factor, logK and apparent viscosity, log(mua), for the power law model, decreased with increasing phosphorus content of starch. When the phosphorus content of these modified starch (cross-linking level) was over 9.00 x 10(-4)% (w/w), the swelling of starch granules was retarded. This led to the small change in logK and log mua values. Flow properties of modified starch suspensions were found to be affected rather by the cross-linking modification of starch than by the acetylated modification.