Optimization of Extraction and Drying Methods of Low-Grade Mulberry Leaf Tea Extract for Encapsulation in Alginate-Pea Protein Hydrogels with pH-Responsive Release Behavior
DOI:
https://doi.org/10.59796/jcst.V16N4.2026.221Keywords:
Alginate–pea protein hydrogel, encapsulation efficiency, phenolic compound encapsulation, mulberry leaf tea residue, phenolic compounds, pH responsive releaseAbstract
This study investigated alginate–pea protein hydrogel beads as an encapsulation material for antioxidants derived from low-grade mulberry leaf tea residue (LGMLT). The quality of LGMLT extract powder was significantly influenced by both extraction and drying methods with freeze drying, particularly when combined with ultrasonication-assisted extraction, providing the highest antioxidant activities (ABTS: 37.12 mg of Trolox equivalents/g and FRAP: 43.90 mg of Trolox equivalents/g) and a total phenolic content (22.97 mg gallic acid equivalents/g) statistically comparable to decoction–freeze drying, while spray drying consistently resulted in higher powder yield across extraction methods. The physicochemical and antioxidant properties of hydrogel beads were strongly dependent on the alginate-to-LGMLT extract ratio; higher alginate content improved bead uniformity, encapsulation efficiency (95.90%), and water-holding capacity (55.94%), whereas increased extract loading enhanced total phenolic content and antioxidant activity. In vitro pH-responsive release studies demonstrated a rapid release of phenolic compounds under pH 1.2, followed by a more sustained release at pH 7.4, reflecting the pH-dependent behavior of the hydrogel matrix. Differences between ABTS and FRAP responses indicated assay-dependent antioxidant capacities influenced by hydrogel composition. Based on these findings, alginate–pea protein hydrogels represent a tunable, food-grade encapsulation system for antioxidants and offer an alternative approach for the valorization of tea-processing residues in functional food applications, contributing to sustainable food production and food security.
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