Insights into cell wall integrity-mediated modulation of starch digestion in processed oat endosperm: From structural barriers to enzymatic accessibility

This study elucidates the regulatory role of cell wall integrity in starch characteristics across oat fractions (F1-F4). Reduced cell wall integrity correlated with increased starch content (62.77 % in F1 to 73.23 % in F4) and diminished β-glucan levels (4.74 % in F2 to 0.59 % in F4). Thermal analysis showed consistent gelatinization temperatures (To: 55.32–56.41 °C; Tp: 59.12–60.70 °C; Tc: 67.22–68.59 °C) across fractions, while gelatinization enthalpy (ΔH) increased from 3.06 J/g (F1) to 4.94 J/g (F4), demonstrating restricted starch gelatinization by intact cell walls. Cell wall integrity critically influenced digestibility: resistant starch (RS) in F1 (46.15 %) doubled F4 levels (22.68 %). Protease pretreatment induced 39.9 % weaker RS reduction in F1 (Δ5.01 %) compared to F4, confirming extracellular protein's differential protection Cellulase treatment triggered rapid slowly digestible starch (SDS)-RS interconversion in F1, reducing RS from 26.9 % to 17.12 % within 15 min. Subsequent rapidly digestible starch (RDS)-RS conversion reached equilibrium by 30 min. Microstructural observations confirmed incomplete gelatinization and restricted enzymatic hydrolysis. Moreover, intact cell walls inhibited α-amylase adsorption in a concentration-dependent manner, reaching 19.13 % inhibition at 20 mg/mL. These findings systematically establish cell wall integrity as a key modulator of starch functionality and digestion kinetics, offering strategic insights for developing functional oat products with tailored glycemic responses.