Tuning structure and digestibility of ginkgo starch-ginkgo biloba extract complexes by pullulanase debranching time

This study investigated the effect of pullulanase debranching time (0, 3, 6, 12, and 24 h) on the complexation between debranched ginkgo starch (DGS) and ginkgo biloba extract (GBE), focusing on the structural characteristics and digestibility of the complexes. Debranching significantly altered the chain-length distribution, increasing the proportions of long chains (DP 25-36) and apparent amylose content. Correlation analysis revealed that the proportion of long chains was positively correlated with the complexation index (CI; r = 0.95, p < 0.05). CI peaked at 63.94% for the DGS-12-GBE sample. X-ray diffraction revealed that the complexes exhibited a combined B- and V-type crystalline structure, with the DGS-12-GBE showing the highest relative crystallinity (19.63%) and short-range molecular order (R₁₀₄₇/₁₀₂₂ = 1.36). This ordered structure was directly associated with a substantial increase in resistant starch (RS5) content, reaching 52.31% for the DGS-12-GBE. These results demonstrate that controlled debranching can effectively tailor starch structure to fabricate starch-polyphenol complexes with enhanced functional properties, offering a promising strategy for the value-added utilization of ginkgo resources.