Oil body proteins derived from oxidation-controllable modified roasted pine nuts reinforce corn starch films via...

To improve the performance of starch films, incorporating plasticizers and protein fillers represents a synergistic enhancement strategy, although interfacial compatibility remains a key challenge. Inspired by the self-assembly of amphiphilic oil body proteins (OBPEs) in aqueous buffers, OBPE-reinforced corn starch (CS)-glycerol films were fabricated via a water-induced microphase separation strategy. OBPEs were extracted from raw pine kernels (K-OBPE) and synergistically oxidized-roasted pine kernels (OR-OBPE) to prepare variant fillers. OR-OBPE reached an extraction yield of 44.05%, with extensive elution of heterologous storage proteins and exposure of polar groups, thus improving compatibility with the starch-glycerol system. CLSM and SEM showed that CS, CS-K-OBPE, and CS-OR-OBPE films presented homogeneous structure, rough microphase separation, and uniform microphase separation, respectively. FTIR and XRD confirmed that OR-OBPE incorporation amorphized the starch matrix, decreasing the R₁₀₄₇/₁₀₂₂ ratio and relative crystallinity by 92.41% and 37.40%, respectively. Second-derivative FTIR indicated that in CS-OR-OBPE, hydrogen bond lengths in inter-strand and double helices decreased while bond energies increased, forming a multi‑hydrogen-bond interlocked structure. Raman spectroscopy confirmed that protein hydrophobic aggregation was inhibited, with ordered secondary structures increasing by 7.04%. Consequently, OR-OBPE-reinforced films exhibited enhanced viscoelastic moduli, with tensile strength, UV-shielding capacity, and bound water retention increased by 110.61%, 69.53%, and 6.97%, respectively, relative to CS films. Soil burial tests demonstrated complete biodegradation of films within 30 days, with CS-K-OBPE showing the highest degradation rate (67.30%). This study regulated microphase separation via starch-OBPE-glycerol synergistic effects, offering guidance for preparing multifunctional starch-based films with high mechanical strength, excellent barrier properties, and controllable solubility.