Unraveling edible-medicinal flavonoids as potential ingredients for regulating starch digestibility: From the perspective of co-gelatinization interaction

This study elucidates co-gelatinization interaction mechanism between corn starch (CS) and three structurally distinct edible-medicinal flavonoids, including baicalein (BA), liquiritigenin (LI), and puerarin (PU). The inhibitory mechanism of co-gelatinization interaction on starch digestion was further investigated. The results of complexing index, iodine binding capacity, and differential scanning calorimetry indicated that the interaction between flavonoids and CS were non-covalent. Increasing flavonoid concentration from 1 % to 20 % raised complexing index for CS-BA, CS-LI, and CS-PU by 164.65 %, 121.34 %, and 117.61 %, respectively. Compared with CS‑iodine complex, BA, LI, and PU at 20 % concentration reduced the absorbance of this complex by 120.34 %, 31.63 % and 475.00 %, respectively. Fourier transform infrared spectroscopy revealed new absorption bands at 2931 cm^-1 and 1651 cm^-1 in CS-flavonoid complexes compared to native CS. X-ray diffraction patterns demonstrated characteristic peaks of V-type inclusion complexes in CS-BA and CS-PU, whereas CS-LI exhibited no such peaks, indicating non-inclusion complex formation. At 20 % flavonoid concentration, BA, LI, and PU increased resistant starch content by 103.95 %, 9.32 %, and 271.36 %, respectively, while reducing rapidly digestible starch content by 33.53 %, 6.17 %, and 111.80 %, relative to untreated CS. PU exhibited the most potent effect on resistant starch formation. This work provides a basis for developing functional foods utilizing edible-medicinal flavonoid-starch co-gelatinized complexes and elucidates novel mechanisms of starch digestion inhibition through their interactions.