Brazilian green propolis-loaded starch nanoparticles: Influence of extraction conditions on bioactivity and kinetic stability under thermal and pH stress.

The bioactivity and physicochemical stability of polyphenols are critical factors for their successful application in formulations. This study aimed to evaluate the influence of extraction method and solvent polarity on the bioactive profile and stability of green propolis extracts adsorbed onto starch nanoparticles (SNPs). Extracts were obtained by maceration (PME) and pressurized liquid extraction (PLE), using 70 % and absolute ethanol, and are hereafter referred to as PME70, PME100, PPLE70, and PPLE100, respectively. These extracts were then incorporated into colloidal and freeze-dried SNPs. The pressurized extract with 70 % ethanol (PPLE70) exhibited the highest yield, total phenolic content (TPC), antioxidant capacity (IC50 = 2.78 μg/mL), and TPC adsorption onto SNPs (92.4 %). In contrast, the macerated extract with 70 % ethanol (PME70) showed superior anticholinesterase activity (IC50 = 4.47 μg/mL). SNP formulations exhibited unimodal hydrodynamic particle size distributions, ranging from 159 to 182 nm, with low estimated polydispersity, which supports their colloidal stability. Lyophilized SNPs significantly improved polyphenol stability under thermal and pH stress, with TPC degradation below 30 % at 115 °C and predicted half-lives exceeding 3400 h at 80 °C. These findings were supported by kinetic modeling under isothermal conditions, providing estimates of degradation rates and shelf life. This study highlights the potential of starch nanoparticles as robust delivery systems for thermosensitive polyphenols in functional food and biomedical applications, while also emphasizing the relevance of green extraction technologies such as PLE, which offer a sustainable and efficient strategy for maximizing bioactive compound recovery.