Effect of Sodium Alginate Concentration on the Physicochemical, Structural, Functional Attributes, and Consumer Acceptability of Gel Beads Encapsulating Tangerine Peel (<i>Citrus reticulata</i> Blanco ‘Cho Khun’) Extract

The effect of varying sodium alginate (SA) concentrations (1%, 2%, and 3%; SA1–SA3) on the encapsulation of tangerine (<i>Citrus reticulata</i> Blanco ‘Cho Khun’) peel extract (TPE, 0.5% <i>w</i>/<i>v</i>) into hydrogel beads was evaluated. Overall, the results showed that increasing SA concentration significantly altered bead characteristics: lightness (L*) decreased from 56.35 to 45.57, red-green axis (a*) shifted negatively from −1.32 to −6.87, and yellow-blue axis (b*) increased from −17.81 to 6.41. Moisture content (97.85% to 93.16%) and water activity (0.96 to 0.93) declined with higher SA, while hardness increased (4.12 to 5.17 g). ζ-potential values shifted from −29.10 mV (SA1) to −39.10 mV (SA3), confirming enhanced electrostatic stabilization. FTIR spectra revealed characteristic alginate functional groups, and morphological analysis showed smoother, denser beads at higher SA concentrations. Phenolic (47.86–48.51 mg GAE g⁻¹ DW) and flavonoid (34.02–36.68 mg QE g⁻¹ DW) contents were well-retained, supporting antioxidant activities (DPPH 70.34–72.54%; ABTS 65.66–66.91%). Antimicrobial tests demonstrated > 4-log reductions against <i>E. coli</i> and <i>P. aeruginosa</i>. Sensory evaluation revealed that higher SA concentrations improved texture and taste. Overall, SA encapsulation, particularly at 3%, effectively stabilized TPE, preserving its functional properties for potential food and nutraceutical applications.