Specific Modification of Granular Potato Starch by Means of Partial Debranching Using Pullulanase

Abstract

AbstractNative potato starch (PS‐N) is enzymatically modified in the granular state using pullulanase (PUL) for the purpose of a specific partial molecular degradation of the polymers. The PUL compound is added to the aqueous starch suspension (40%, w/w) and processed. The process parameters are varied systematically (enzyme dosage [ENZ] 4/20 mL; pH of the suspension [pH 4.7/7.3]; hydrolysis temperature [TEMP] 40/50 °C, and hydrolysis duration [TIME] 20/120 min) and a new‐developed heat‐induced enzyme inactivation approach (storage of the partially dewatered moist starch for 120 min at 100 °C) is intended to terminate the hydrolysis. Morphological (LM, SEM, and CLSM) and thermal characterization (DSC) of the starch products indicate a partial damage of the granules and a partial loss of the semicrystalline structure owing to the heat treatment, which is confirmed by XRD. The molecular properties (SEC‐MALS‐DRI) are mainly controlled by the factors ENZ, pH, and TEMP, but the intended degradation of the amylopectin (AP) by cleavage of the α‐1,6‐linkages (debranching) is accompanied by a molecular degradation of the amylose (AM) fraction. However, both specificity of the hydrolysis and achievable gel strength are remarkably improved compared to acid‐thinned products.