Molecular interactions and thermal stability of betacyanins encapsulated with hydrocolloids: A combined DFT and experimental study.

Abstract

This study investigated betacyanin stabilization from red dragon fruit peel using integrated computational and experimental approaches. HPLC identified betanin and phyllocactin as primary components. Density Functional Theory (DFT) screened molecular interactions, identifying sodium alginate (SA) and low-methoxyl pectin (LMP) as wall materials due to strong binding affinities. Consequently, maltodextrin (MD) composites with SA or LMP (1-3% w/v) were freeze-dried. Experimental results support the DFT screening trends; MD-SA2 and MD-LMP2 achieved higher betacyanin content (93.81 and 88.00 mg/100 g, respectively) than the MD control (77.93 mg/100 g). FTIR confirmed interactions consistent with optimized DFT structures. Thermal degradation (60-80 °C) followed first-order kinetics (R2 > 0.98). Encapsulated betacyanins showed high stability at 80 °C (t₁/₂ = 26.41-26.87 min), outperforming the non-encapsulated betacyanins. High retention (>94%) was maintained during pasteurization (72 °C, 15 s). These findings demonstrate that molecularly guided ionic hydrocolloid systems show potential to protect sensitive pigments during thermal food processing.