Physicochemical characterization of dextrins prepared with amylases from sorghum malt

Dextrins are partially hydrolyzed starch products which are used in a wide range of applications.
Hydrolysis can be performed by acid or enzymatic reaction. However the properties of dextrins
are influenced by the type of reaction and the source of starch. The aim of the present study was to
determine physicochemical properties of dextrins obtained from hydrolysis of starches (corn and
wheat) and flours (wheat and cassava) by using sorghum malt amylases. Hydrolysis of starches
and flours was performed at 65°C, the hydrolysates were centrifuged and spray-dried for analysis.
Physicochemical and structure of the powders were investigated. Results showed that the
proportion of DP2 (maltose and isomaltose) was higher in dextrins and more in dextrins from
wheat flour. Low water activity and low dissolution time were found in all dextrins. XRD patterns
revealed that the crystalline structure partially disappeared in some of them. At 30%
concentration, we noted a Newtonian behavior for the dextrins. The freeze-concentrated T0 g and the peak melting temperature (T0 m) determined by DSC (DSC) showed lowest values for dextrins from wheat. Thermogravimetric analysis (TGA) revealed that the dextrins were quite stable until 200°C.