Characterization of different high amylose starch granules. Part III: How starch fine structures affect retrogradation and formation of type 3 resistant starch

The effects of amylose (AM) content (AC) and starch fine structures on the retrogradation and type 3 resistant starch (RS3) formation were investigated using seven starches with various fine structures and ACs ranging from 27 % to 97 %. RS3 contents ranged from 31.9 % to 50.3 %, without a linear increase with AC. However, thermally stable RS3 contents obtained through reheating increased with AC before plateauing at 57 %, ranging from 18.3 % to 39.5 %. Retrograded amylopectin (AP), AM-lipid complexes, and retrograded AM crystals were identified. Notably, as AC reached 57 %, a transition from AP to AM retrogradation was observed. Greater retrogradation degree and structural order induced higher RS3. Retrograded AP, AM-lipid complexes, and retrograded AM were likely composed of AP chains with degree of polymerization (DP) 13–24, AM chains with DP 500–5000, and short AM chains with DP < 500, respectively. RS3 in these HASs comprised a mixture of double-helical and single-helical structures, with their levels likely enhanced by increasing amounts of AM chains with DP < 5000 and AP chains with DP > 36, respectively. These findings provided insights into developing functional foods with desired retrogradation degree and RS3 by controlling AC and fine structures of AM and AP.