Extraction of Anthocyanin from Purple Sweet Potato Using Ultrasound-Assisted Natural Deep Eutectic Solvents and Its Application for Smart Packaging Film

This study focused on extracting anthocyanin (AC) from purple sweet potato (PSP; Pyrus communis (L.) Lam) using ultrasound-assisted natural deep eutectic solvents (NADES) and incorporating them into biodegradable smart packaging. The effects of water content (40–60%), ultrasound power (40–60%), and extraction time (15–45 min) were optimized using the three-dimensional Box-Behnken design of response surface methodology (RSM). AC content was obtained under 128.90 ± 0.68 mg/100 g at experimental optimal conditions suggested by the RSM model while the predicted value was 130.99 mg/100 g PSP. The obtained AC-NADES extract was used for smart packaging films based on starch (S) and gelatin (G). The optimized AC-NADES extract exhibited superior biological activity and chemical profile compared to conventional solvents. Incorporating NADES as both a plasticizer and extraction medium improved water vapor permeability, elongation at break, and tensile strength while enhancing the film’s antioxidant properties and color. However, AC-NADES films showed lower thermal stability than the control film. Scanning electron microscopy and Fourier transform infrared spectroscopy confirmed strong interactions among AC, NADES, and biopolymers. In conclusion, using NADES in ultrasound-assisted extraction to develop AC smart films shows significant potential for smart packaging applications, offering improved antioxidant properties and water resistance.