Flaxseed Hydrocolloid as a Natural Encapsulating Material for Spray-Dried Phenolic Compounds from Andean Tubers (Oxalis tuberosa and Tropaeolum tuberosum)

The microencapsulation of plant bioactive compounds by spray drying enhances their stability and controlled delivery in food systems. In this study, flaxseed hydrocolloid (Linum usitatissimum L.) was evaluated as a natural wall material for encapsulating phenolic extracts from mashua (Tropaeolum tuberosum Ruiz & Pav.) and oca (Oxalis tuberosa Molina). Microcapsules were produced using hydrocolloid concentrations of 2.5–10%. The resulting particles showed low moisture content (3.79–5.42%), low water activity (0.31–0.39), and high solubility (90.94–96.45%). Encapsulation efficiency ranged from 78.67 to 62.32% for mashua and from 71.94 to 40.45% for oca, decreasing with increasing wall material concentration. Phenolic content ranged from 14.48 to 11.47 mg GAE/g (mashua) and 8.52 to 4.82 mg GAE/g (oca), with antioxidant capacity between 293.19–143.77 and 84.49–10.33 µmol TE/g, respectively. Particle size ranged from 4.02–10.50 µm (mashua) and 3.93–4.82 µm (oca), and zeta potential values (−37.86 to −27.55 mV) indicated good colloidal stability. Release kinetics showed a biphasic profile and were predominantly diffusion-controlled. The Higuchi model showed significant diffusion (p < 0.05), while the Korsmeyer–Peppas analysis indicated mainly Fickian diffusion (n = 0.234–0.426) with anomalous transport at higher mashua concentrations. These results demonstrate that flaxseed hydrocolloid is an effective and sustainable wall material for controlled release of phenolic compounds from Andean tubers.