Microencapsulation of ultrasound-assisted phenolic extracts of sugar maple leaves: Characterization, in vitro gastrointestinal digestion, and storage stability

Sugar maple leaves (SML), usually considered residue plant biomass and discarded accordingly, contain a considerable amount of phenolic antioxidants. In this study, SML phenolics were extracted employing both advanced (homogenization pretreated ultrasound-assisted extraction) and conventional (maceration) methods followed by their encapsulation by freeze drying and spray drying using a combination of maltodextrin and gum arabic as coating agents. Detailed physicochemical analyses revealed that the encapsulated microparticles had high solubility (>90 %) and encapsulation efficiency (>95 %), acceptable thermal stability with good handling properties. Phenolic compounds were completely released from microparticles during simulated gastric conditions. The microparticles influenced the bioaccessibility of more than 43 % of the phenolic fraction in the intestinal phase. The antioxidant capacity of the microparticles was preserved during storage. These findings suggest the effectiveness of the microencapsulation process for producing high quality microparticles of SML phenolic extracts and the possibility of their use in the food, nutraceutical, bio-pharmaceutical sectors.