Enzymatic Modification of Granular Potato Starch Using Isoamylase-Investigation of Morphological, Physicochemical, Molecular, and Techno-Functional Properties

Granular potato starch is modified using the debranching enzyme isoamylase. The modification is performed in aqueous suspension (40% w/w) at 35 degrees C by grading the volume (100, 250, and 400 mu L/50 g of starch, 200 U center dot mL(-1)) of enzyme solution added. The starch products obtained are comprehensively investigated in terms of morphological (scanning electron microscopy), structural (X-ray diffraction), thermal (differential scanning calorimetry), techno-functional (solubility, hot paste viscosity, gel strength), and molecular properties (size exclusion chromatography-multi angle laser light scattering-differential refractive index detection). The granular integrity is basically preserved after modification and a molecular degradation predominantly of the amylopectin by debranching is proved. However, a slight reduction of the weight average molar mass of the amylose fraction is found too. In addition, the intended partial molecular degradation of the starch polysaccharides, the effect of the preparation procedure including washing with ethanol and grinding impacts several starch characteristics conspicuously.