From surface adsorption to V-type inclusion complexes: Amylose-driven structural regulation of cyanidin-3-O-glucoside binding and functionality in rice starch matrix

-glucoside (C3G) and waxy (WS, 0% amylose), low-amylose (LS, 15.71%), and high-amylose (HS, 35.74%) rice starches under native (N) and hydrothermally treated (T) conditions, relevant to black rice. In native granules, amorphous amylose-C3G interactions involved non-inclusion hydrogen bonding, leading to gradual granule swelling, especially in HS-N. Waxy starch (WS-N) exhibited the highest bioaccessibility (25.6%) and a significant blue shift in chrominance caused by weak surface adsorption of C3G. Amylose contents improved C3G binding, and formed labile V-type complexes, while thermal treatment disrupted lamellar order, shifted starch fractions towards digestible forms, and caused granule fragmentation. DCI analysis indicated that hydrothermal treatment had a minor advantage on regulating C3G bioaccessibility than amylose contents. Collectively, these findings provide mechanistic insights for designing black rice-based functional food ingredients with modified anthocyanin bioaccessibility profiles.