Physically Modified Cassava Starch Microparticles as Carrier Systems for Bioactive Compounds from Green Propolis Extract

The development of starch-based carrier systems for natural bioactive compounds is a promising strategy for improving the stability of bioactive ingredients and enabling controlled release. Cassava starch is an attractive biopolymer for this purpose because of its biodegradability, biocompatibility, and wide availability; however, its native structure may limit its performance as a carrier material. Dry heat treatment (DHT) is a physical modification that alters the structural and functional properties of starch. Therefore, this study evaluated the effect of starch modification by DHT on the properties of cassava starch microparticles produced by antisolvent precipitation using green propolis hydroethanolic extract (GPE) as a source of bioactive compounds. GPE was obtained by extraction with 80% (v/v) ethanol (50 °C/ 30 min), whereas cassava starch was subjected to DHT (130 °C/ 4 h). Starch microparticles were evaluated for production yield, average hydrodynamic diameter (laser diffraction), morphology (SEM), zeta potential, FTIR spectra, adsorption capacity, loading capacity, and the time-dependent release profiles of phenolic compounds and flavonoids (0, 0.5, 2, 4, 6, 9, and 24 h). Microparticles produced from native starch (NSM) and DHT-modified starch (MSM) exhibited high production yields (78 ± 1.21% and 72 ± 1.19%, respectively) and high adsorption capacity (51.95 ± 2.23%), with a loading capacity of 12.71 ± 1.14 mg GAE/g particles, indicating efficient incorporation of bioactives compounds regardless of starch modification. FTIR analysis confirmed the presence of GPE compounds within the microparticles. Compared with NSM, MSM formed smaller (200 vs. 262 µm), denser, and less porous particles, which were associated with lower release of phenolic compounds (381.61 ± 8.40 vs. 456.00 ± 6.60 µg GAE/mL) and flavonoids (3.41 ± 0.18 vs. 4.12 ± 0.25 µg QE/mL) after 24 h. In addition, both formulations exhibited low zeta potential values (−17.34 ± 1.32 mV for NSM and −8.69 ± 1.18 mV for MSM), indicating limited colloidal stability. Overall, starch modification by DHT altered the microstructure of cassava starch microparticles, maintaining phenolic compound retention while promoting slower release of bioactive compounds. These findings highlight the potential of DHT as a clean-label modification for tailoring the release profile of starch-based carriers for natural bioactive compounds.