Sustainable, functional food design: Characterizing and utilizing passion fruit by-product extract in anthocyanin-enriched delivery systems

This study evaluated various conditions, including ethanol concentration (60 to 80 %) and ultrasonic power (300 to 500 W), to determine the optimal ultrasound-assisted extraction (UAE) parameters for anthocyanins from purple passion fruit (Passiflora edulis f. edulis) peel. The results identified that UAE at 500 W for 10 min using 80 % ethanol was the most effective condition, yielding 6.47 mg GAE/g of total phenolic content and 0.28 mg CYE/g of total anthocyanins. The extract demonstrated a significant 62 % inhibition of reactive oxygen species generation in human red blood cells and exhibited cupric-ion-reducing antioxidant capacity (27.45 mg AAE/g). In a gummy model, adding the optimal extract followed by in vitro digestion simulation increased the bioaccessibility of anthocyanins by 112 % and the total phenolic content by 163 %. The extract also enhanced the ferric-reducing antioxidant power (FRAP) with a bioaccessibility of 128 %, while the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity decreased after digestion (bioaccessibility of 84 %). However, gummies made with sucrose and artificial red pigment achieved a higher acceptability index (76 %) than those with passion fruit peel extract (66 %). In conclusion, we identified the optimal extraction conditions for producing a food-grade and sustainable extract rich in anthocyanins. This extract can be utilized as a natural coloring and antioxidant in functional food applications.