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

摘要

Waxy maize starch was modified doubly by acetylation and cross-linking with acetic vinyl and phosphorus oxychloride (POCl3). The degree of cross-linking varied when 0.008-0.020% phosphorus oxychloride was used; acetylated substitution was adjusted to the same degree on all starch samples. Flow properties of the starch suspensions were determined by using a capillary tube viscometer. Flow parameters were markedly changed over 1.21x10-4% (w/w) of the phosphorus content. Logarithmic value of the consistency factor (logK) and apparent viscosity (log mu a) for the power law model, decreased with increasing phosphorus content in starch. When phosphorus content of the modified starch (cross-linking level) was over 9.00x10-4% (w/w), the swelling of starch granules was retarded. This led to the small change in logK and log mu a values. Flow properties of modified starch suspensions were found to be more affected by the cross-linking modification of starch than by the acetylated modification.