CO₂-Based Encapsulation of Rutin-Rich Extracts from Black Elderberry Waste Using Advanced PGSS Process

For the first time, rutin-rich extracts from black elderberry waste (BEW) were encapsulated using the particles from gas-saturated solutions (PGSS) method to improve the preservation of rutin. The extracts used in this study were obtained using five different extraction techniques under optimal conditions, as follows: conventional solid–liquid extraction (SLE) and four non-conventional techniques—ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), enhanced solvent extraction (ESE), and supercritical CO₂ pretreatment—followed by ESE (SFE-CO₂ + ESE). The PGSS process of the obtained extracts was performed using two amphiphilic carriers, glycerol monostearate (GlyMS) and gelucire (Gel), in a mass ratio of 1:6, in favor of the carrier. The efficiency of the PGSS process was evaluated based on the encapsulation yield (EnY), encapsulation efficiency (EE), and physical properties of the encapsulated extracts. The results showed that the SLE extract encapsulated with GlyMS had the highest EnY (92.47%). The Gel only in combination with the ESE extract exceeded the 50% efficacy threshold, with an EnY of 55.18%. The encapsulated SLE extract with Gel showed excellent flow properties and the highest EE (98.91%). These results emphasize the advantages of the PGSS process, including its efficiency and adaptability to produce encapsulated rutin-enriched BEW extracts for pharmaceutical, nutraceutical, and cosmetic applications.