Transitions in structural, functional, and digestibility properties of durum wheat starches with normal, intermediate, and high amylose levels

This study elucidated the relationships among structure, functionality, and digestibility of durum wheat starches (DWS) across a wide range of amylose content. DWS1–6 with 36.6%–65.7% apparent amylose were isolated from six durum wheat lines, which were extensively characterized and compared with a commercial normal wheat starch (NWS). As the amylose content and the proportion of amylopectin long branch chains (LBC) increased, X-ray diffraction patterns transitioned from A-type (NWS and DWS1) to C-type (DWS2–3), and eventually to B-type (DWS4–6). These structural changes led to progressive increases in gelatinization temperatures and retrogradation rates from DWS1 to DWS6. Under 95 °C–140 °C heating in Rapid Visco Analyser (RVA 4800), NWS and DWS1–6 exhibited three distinct pasting behavior patterns: normal- (NWS and DWS1), intermediate- (DWS2–3), and high-amylose groups (DWS4–6). Resistant starch (RS) content gradually increased from DWS1 to DWS6 in a raw state; notably, high-amylose DWS6 maintained the highest enzymatic resistance even after cooking. Principal component analysis (PCA) classified DWS1–6 into three distinct sub-groups: normal- (DWS1), intermediate- (DWS2–3), and high-amylose (DWS4–6) groups. The new understanding of the structure-function-digestibility relationships in DWS offered valuable insights for the agri-food industry to develop novel starch and semolina ingredients with tailored functional and nutritional properties from diverse durum wheat lines.