Sustainable Ultrasound-Assisted Extraction and Encapsulation of Phenolic Compounds from Sacha Inchi Shell for Future Application

Sacha inchi shell (SIS), an underutilized by-product of sacha inchi oil processing, is a rich source of phenolic compounds. In this study, ultrasound-assisted extraction (UAE) was optimized by response surface methodology (RSM) with a Box–Behnken design to investigate the effects of time (15–25 min), temperature (25–45 °C), and ethanol concentration (40–80%) on the total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity by DPPH assay of the obtained extracts. The maximum TPC was at 15 min, 45 °C and 60%, TFC at 25 min, 45 °C and 60% and DPPH at 15 min, 35 °C and 80%. The optimized condition selected for encapsulation purposes was at 25 min, 35 °C and 80% ethanol concentration. RSM analysis showed that all models analyzed for all three assays were significant at 95% confidence. The SIS extract had a greater inhibitory zone against Escherichia coli measuring 15.34 mm at a concentration of 30 µg/mL than Staphylococcus aureus among the samples. The spray-dried microcapsules using different combinations of gum arabic and maltodextrin (GMM 1 and GMM2) resulted in a proper encapsulation layer and a smoother surface and shape obtained at 1000× magnification. Also, GMM 1 and GMM2 had particle sizes ranging from 2.95 ± 0.02 to 27.73 ± 0.38 and from 5.20 ± 0.01 to 29.30 ± 0.42 µm, respectively. The microcapsules were in the acceptable ranges for moisture content (<5%) and water activity (<0.6). It has been concluded that SIS extract showed high antioxidant and antimicrobial properties and its encapsulation could be further used in food and nutraceutical formulations.