Influence of selected parameters of starch gelatinization and hydrolysis on stability of amylose-lipid complexes

摘要

Dissociation of amylose - lipid complexes (AMLs) upon gelatinization and enzymatic hydrolysis of wheat starch has been examined using differential scanning calorimetry (DSC). Digestion of starch by the thermostable alpha-amylase THERMAMYL 120L was carried out under conditions applied for enzymatic hydrolysis of wheat starch in industry, i.e. 5 min incubation at 105 degrees C, followed by 60-90 min hydrolysis at 95 degrees C. For comparison reasons, samples of wheat starch slurries were incubated under the same conditions but in the absence of enzyme. The enthalpy and temperature of AMLs dissociation and the shapes of peaks in the DSC endo- and exotherms depended on conditions of starch processing prior to DSC measurements. Wheat starch gelatinization coupled with its digestion by alpha-amylase resulted in more pronounced AML degradation as compared to gelatinization in the absence of enzyme. Different shapes of peaks in thermograms and different temperatures of AMLs dissociation and reassociation indicate that different AML polymorphs were generated in the examined samples. Their concentrations depended on conditions (temperature, time and the presence or absence of alpha-amylase) of wheat starch treatment.