Some physico-chemical and thermodynamic characteristics of maize starches hydrolyzed by glucoamylase

Glucoamylolysis of maize starch at 55 degrees C has been studied by means of scanning electron microscopy (SEM), wide-angle X-ray diffraction spectroscopy (WAXD), and differential scanning calorimetry (DSC). It was found that hydrolysis is accompanied by changes in thermodynamic parameters of diluted aqueous dispersions of partially hydrolyzed starches. Such changes are ensured by two processes directly from hydrolysis and accompanying annealing. At relatively low degrees of hydrolysis (less than 30%), changes in thermodynamic parameters are mainly controlled by annealing. At the same time, at high degrees of hydrolysis (more than 40%), the main contribution to changes in thermodynamic parameters of partially hydrolyzed starch granules is due to the hydrolysis itself. It has been established that the main controlling parameter is the thickness of crystalline lamellae L-crl, which, when annealed, increases, but tends to decrease at deeper glucoamylolisis. It has been established that the thickness L-crl of crystalline lamellae, which increases with annealing, but shows a tendency to decrease with deeper glucoamylolysis is the most representative parameter of changes in maize starch after hydrolysis.