Betaine-based deep eutectic solvents extraction enhances the emulsification and antioxidant activity of Camellia...

Camellia oleifera leaves, a by-product of the pruning process in cultivation, are rich in various bioactive components. Extracting active ingredients efficiently and sustainably from by-products has garnered widespread attention in the oilseed industry. This study utilized 11 combinations of deep eutectic solvents (DESs) to extract polysaccharides from C. oleifera leaves (CLPs). Betaine - Lactic acid (Bet-LA) deep eutectic solvent achieved the highest polysaccharide extraction yield, reaching 19.01 % under optimal conditions, a 2.5-fold increase compared to conventional hot water extraction. The physicochemical composition and preliminary structural features of CLPs were also characterized. The polysaccharide extracted using DES (CLPD) exhibited a similar monosaccharide profile and chemical composition to that extracted with hot water (CLPW). Still, it possessed a significantly lower molecular weight (96.56 kDa compared to 775.76 kDa) and a smaller particle size. Moreover, CLPs demonstrated better thermal stability, emulsifying stability, and in vitro antioxidant activities, achieving a DPPH radical scavenging rate of 91.7 % at 0.5 mg/mL. These findings highlight the potential of DES-extracted CLPs as natural antioxidants or functional emulsifiers for use in the food, pharmaceutical, and cosmetic industries, providing a sustainable and efficient strategy for the green exploitation and utilization of C. oleifera by-products.