The surface characteristics of alginate were enhanced by its modification with different concentrations of octenyl succinic anhydride (OSA) (4%, 8%, 12% based on the dry weight of alginate). The degrees of succinylation (DS) of OSA-modified alginate (OS-ALG) were 0.014, 0.022, 0.034 corresponding to minimum DS, FDA-suggested DS, and maximum DS, respectively. Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance ( 1 H NMR) spectroscopy, and zeta potential test proved the grafting of OSA groups onto the molecular structure of alginate. Meanwhile, the XRD analysis revealed the higher amorphous structure of alginate after esterification. The results of thermogravimetric analysis and apparent viscosity showed that the modification of alginate enhanced its thermal stability and viscosity. Also, OS-ALG exhibited an improvement in the emulsifying and foaming capacities when the DS was increased. Furthermore, this modification had a significant positive effect on the bead’s properties (increase in SWC, EWC, GF, and hardness). As confirmed by SEM observation, the bead skeleton structure of OS-ALG showed a fine porous network compared to that of the pristine alginate. The modified alginate could be a promising candidate for improving the long-term stability of emulsions and encapsulation of bioactive compounds.
The effect of succinylation of sodium alginate (ALG) by octenyl succinic anhydride (OSA) and its effect on some properties of the bergamot essential oil (BEO)-loaded ALG beads was evaluated. The physico-chemical, antioxidant, antibacterial, and in vitro release properties of BEO-loaded ALG beads were assessed. The presence and amount of BEO in alginate beads was assessd using Fourier transform-infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and differential scanning calorimetry (DSC) experiments. In addition, it was discovered that the degree of substitution (DS) of ALG has notable effects on encapsulation efficiency (EE), loading capacity (LC), so that the values of EE and LC were about 31–75% and 19–45%, respectively, when the DS value of ALG was 0.00 – 0.022. Besides, BEO-loaded beads, exhibited higher total phenolic compound (TPC), good antioxidant activity and antibacterial properties. The release of BEO from the beads followed Fickian diffusion with acceptable release.
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