HYDROTHERMAL TREATMENT OF STARCH IN THE P RESENCE OF ALPHA-AMYLASE .2. EFFECT OF A HYDROTHERMAL ENZYMATIC MODIFICATION ON THE SWELLING TEMPERATURE OF WHEAT STARCHES

The hydrothermal treatment of wheat starch in the presence of bacteria l-alpha-amylase is directed to the production of modified residual sta rches with a maximal shift of swelling temperature T(max) (measured by DSC) at high yields. The annealing of granular starch at temperatures below the swelling temperature (50-degrees-C) in presence of alpha-am ylase gives no difference regarding the shift of T(max). Because of th e hydrolysis of swollen material it is possible to use higher reaction temperatures and the process becomes more effective. The formed malto se syrup retards the shift of T(max) and protects the granules. Within 24h wheat starch can be modified with a yield of 70% and a shift of T (max) of 8K.