黄大茶水提物对高直链玉米淀粉结构与消化的剂量调控OA

To promote the high-value utilization of summer-autumn large-leaf yellow tea resources,this study investigated the dose-dependent effects of large-leaf yellow tea aqueous extract(YTWE)on the multi-scale structure and digestive properties of high-amylose maize starch(HAMS).YTWE was added at 0％,5％,10％and 15％(based on starch dry weight)and co-gelatinized with HAMS at 120℃ to prepare tea-starch complexes(TSC).The thermodynamic properties,water status,crystalline structure,short-range order parameter,microstructure and digestibility of TSC were analyzed using DSC,LF-NMR,¹H-NMR,XRD,FT-IR,SEM and the Englyst in vitro digestion model.The results indicated that with the increase in YTWE dosage,the gelatinization onset temperature(T0)increased,while the gelatinization enthalpy(ΔH)decreased from 5.35 J/g to 2.90 J/g.The free water in the starch gel was gradually transformed into multi-layer water,and the proton resonance peak shifted to a lower magnetic field.Both relative crystallinity and the 1 047/1 022 cm-1 ratio(short-range order)increased in a concentration-dependent manner.In vitro digestion revealed a bidirectional dose-dependent effect of YTWE on starch digestibility.Compared with the control(GHACS),5％YTWE increased rapidly digestible starch(RDS)from 59.74％to 70.26％,decreased resistant starch(RS)from 25.01％to 10.39％,and raised the final hydrolysis degree(C∞)from 75.05％to 86.79％.In contrast,15％YTWE reduced the RDS content to 43.51％,increased the RS content to 43.87％,and decreased C∞ to 60.26％.YTWE interacts with HAMS through non-covalent interactions such as hydrogen bonding.At low concentration(5％),YTWE mainly disrupts the ordered structure of starch and exposes enzyme cleavage sites,thereby promoting digestion.At high concentration(15％),it induces the formation of a denser and more ordered gel network,increases crystallinity,and restricts water mobility,thus significantly inhibiting digestion.This study revealed the non-linear dose-dependent effect of crude yellow tea extract on starch digestibility and its multi-scale structural basis,providing a theoretical reference for regulating starch digestibility and utilizing large-leaf yellow tea by-products.