Beyond Encapsulation: Inulin and Polydextrose as Dual-Function Carriers for Bioactive Preservation and Functional...

Background/Objectives: Elderflower (Sambucus nigra L.) extract is a rich source of bioactive compounds with promising metabolic and gut health benefits. This study aimed to develop high-quality microencapsulates and evaluate the effects of inulin and polydextrose, used individually or in combination, on their stability, bioactivity, technological performance, and functional properties. Methods: Spray-drying was employed to produce four powder formulations: extract without a carrier addition, extract with 20% inulin or polydextrose addition, and extract with a combination of 10% inulin and 10% polydextrose. The resulting microparticles were characterized by their technological properties, such as powder yield, moisture content, bulk density, and tapped density. Fourier transform infrared spectroscopy, particle size distribution, and differential scanning calorimetry were used to define their physicochemical properties, while biological activities were evaluated using in vitro assays. Results: Carrier composition substantially influenced particle size, with inulin producing the smallest and most narrowly distributed particles. Incorporation of the extract into carbohydrate matrices promoted amorphous structure formation and enhanced thermal stability, while increasing rutin solubility by nearly 50-fold compared with its reported aqueous solubility. The extract's biological activity was associated with its high polyphenol content, particularly chlorogenic acid and rutin, while microencapsulation effectively preserved the phenolic profile during storage. In addition to displaying potent DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging capacity and α-glucosidase inhibitory potential, the developed formulations exerted biological functionality on inhibiting Gram-positive bacteria and yeasts while fostering the growth of probiotic Lactobacillus strains. Formulations containing inulin, alone or combined with polydextrose, demonstrated the most promising overall biological potential. Conclusions: Inulin and polydextrose demonstrated dual functionality as carriers by protecting elderflower bioactives while enhancing their functional properties, highlighting the potential of the resulting microencapsulates as multifunctional ingredients for food, pharmaceutical, and nutraceutical applications.