Modification of pasting properties of wheat starch by cyclodextrin glycosyltransferase

The effect of cyclodextrin glycosyltransferase (CGTase) on wheat starch functionality was assessed by determining the pasting properties and the dynamic rheology. The addition of CGTase lowered the peak and final viscosity, increased breakdown and markedly decreased the total setback. The influence of CGTase on the ability of starch to form complex with lipids was explored in the presence of fatty acids (stearic and lauric) and an emulsifier (diacetyl tartaric acid ester of monoglyceride, DATEM). Further information about the effect of CGTase on the pasting properties of wheat starch was obtained by analysing the first derivative of the viscograph curves. The cyclodextrins formed in the starch as a result of the cyclization activity of the CGTase were quantified and it was observed that a-cyclodextrin occurred in the highest concentration followed by beta- and gamma-cyclodextrins. The starch obtained with CGTase after pasting exhibited better emulsifying properties as it contained the cyclodextrins. The CGTase treatment also modified the dynamic rheology of the starch slurry leading to a decrease in the elastic and viscous modulus. (C) 2004 Society of Chemical Industry.