Optimization and characterization of alginate-chitosan beads for controlled release of red onion (Allium cepa L.) peel polyphenols

초록

In this study, encapsulation efficiency (EE) of recovered red onion peel polyphenols (MRP) in sodium alginate-chitosan beads was optimized using response surface methodology (RSM). The effects of sodium alginate concentration (X₁), chitosan concentration (X₂), and hardening time (X₃) were evaluated, with optimized conditions determined as X₁ = 1.74%, X₂ = 0.98%, and X₃ = 15 min, achieving an EE of 81.52%. Fourier-transform infrared spectroscopy (FTIR) confirmed molecular interaction between MRP and the alginate-chitosan matrix, including hydrogen bonding and electrostatic forces. Additionally, the release study of MRP was investigated using four different food models. The highest release (94.63%) was observed in 50% ethanol, while the lowest release (85.33%) was observed in 3% acetic acid. The release data fit the Korsmeyer–Peppas model well, indicating the release was controlled by Fick’s diffusion law. Furthermore, in vitro digestion systems demonstrated the controlled release under gastric (44.45%) and intestinal (68.57%) conditions, ensuring sustained delivery throughout both phases. Incorporating MRP significantly enhanced antioxidant activity, with ABTS and DPPH radical scavenging capacities of 63.77% and 68.02%, respectively, at 4 mg/mL. The optimized beads exhibit strong antioxidant properties and sustained polyphenol release in different food models and simulated digestion conditions, highlighting their potential as an efficient bioactive delivery system for functional food applications. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2025.

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