Effect of pilot-scale steam treatment and endogenous alpha-amylase activity on wheat flour functional properties

Flour steam treatment is an effective industrial process that aims to modify the functional properties of flours. Its effects depend on both the setting parameters of the application and the intrinsic properties of the native flour used. In order to control the effect of these parameters, wheat flours presenting high and low initial alpha-amylase activities were subjected to various steam injection volumes on a pilot-scale level. All the processed wheat flours showed a higher gelatinization temperature, higher pasting profiles, higher water absorption indexes and lower solubility indexes. Changes induced by this treatment seem closely dependent on injected steam volume. Three main mechanisms appear to be involved in these modifications: endogenous alpha-amylase activity reduction, partial starch gelatinization and protein denaturation. Steaming can be used to normalize harvested wheat lots with initial amylase activities considered as excessive.