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Chromatographic Study of High Amylose Corn Starch Genotypes – Investigation of Molecular Properties after Specific Enzymatic Digestion

Ulbrich, Marco; Scholz, Fanni; Flöter, Eckhard

FG Lebensmittelverfahrenstechnik

Two high amylose corn starches (HACS; HYLON V and HYLON VII) are dissolved completely and subjected to specific enzymatic degradation by means of different amylases (AMY). The starches are digested using α‐, β‐, and γ‐AMY (single) as well as in combination with the debranching enzyme pullulanase (PUL; α‐AMY‐PUL and β‐AMY‐PUL), and the products are characterized by means of size exclusion chromatography (SEC)‐techniques including multi angle laser light scattering‐differential refractive index detection (SEC‐MALS‐DRI) and conventional calibration‐differential refractive index detection (SEC‐cal‐DRI). Enzymolysis is resulted in largely maltose (Mal; α‐ and β‐AMY and respective combinations with PUL) or glucose (Glc; γ‐AMY; almost complete digestion) as the major fraction, but also other residual fractions of higher molar mass (MM), i.a. α‐ and β‐limit dextrins (α‐/β‐LDs). The quantity (relative portion) and quality (specific molecular properties) of the reaction products are found to be strongly dependent on both the enzymatic treatment by itself (kind of enzyme/‐combination and associated specificity of action) and the molecular composition of the initial starch (portion and specific molecular properties of the amylose [AM], intermediate [IM], and amylopectin [AP] fraction), which is further investigated in detail.