Comparative evaluation of free and encapsulated Ziziphus jujuba extract in functional beverages using alginate and alginate-soy protein isolate beads

The use of encapsulation and biopolymer-based carriers provides an efficient strategy to develop functional beverage systems by improving the physical stability of bioactive constituents. In this study, beads for beverage formulation were prepared by encapsulation with alginate-based carriers and subsequently coated with soy protein isolate (SPI). Three beverage formulations were produced and evaluated, including a free-extract beverage (free extract), an alginate-bead encapsulated beverage (ALG beads), and an alginate/SPI bead encapsulated beverage (ALG/SPI beads). The pH, acidity, Brix, viscosity, and physical stability parameters were assessed during 14 days. The pH and acidity variations were attributed to the gradual release of small amounts of encapsulated extract components, which influenced the beverage’s equilibrium. With respect to viscosity (ALG: 48.7 cp. ± 0.50 and ALG/SPI: 45.6 ± 0.30 cp.) and related stability, the encapsulated systems exhibited greater resistance to phase changes than the free-extract beverage (60.7 ± 0.50 cp.). Notably, neither sedimentation nor visible phase separation was observed in any formulation, and complete suspension behavior was maintained throughout the storage period, indicating satisfactory gravitational and colloidal stability. Moreover, the beverage containing ALG/SPI beads exhibited superior physical stability. This enhancement is attributed to the formation of a reinforced composite network within the beads, where the interaction between alginate and SPI increases the mechanical strength of the capsules. This structural reinforcement minimizes bead deformation and aggregation, allowing the encapsulated system to maintain better dispersion and resistance to sedimentation within the beverage matrix. Overall, the results demonstrate that the alginate/SPI coating strategy improves the stability of the functional beverage, offering a promising carrier system for maintaining quality attributes during storage.