Optimization of the Extraction Process of Rapeseed Glucosinolate by Deep Eutectic Solvent Method and Study on Its Antioxidant Activity

Rapeseed glucosinolate has physiological functions such as antioxidation. To extract rapeseed glucosinolate safely and efficiently, the extraction process of rapeseed glucosinolate was optimized through single-factor experiments and response surface experiments based on the selection of appropriate deep eutectic solvent, and the antioxidant activity of rapeseed glucosinolate was evaluated. The results show that the suitable deep eutectic solvent is choline chloride-lactic acid (with a molar ratio of 1∶2), and the optimal extraction process is a liquid-solid ratio of 38∶1 (mL/g), water addition of 29%, extraction time of 31 min, and extraction temperature of 51 ℃. Under these conditions, the yield of rapeseed glucosinolate is (236.308±11.820) mg/g. Within the range of rapeseed glucosinolate concentration of 0.05-0.25 mg/mL, the rapeseed glucosinolate extracted by choline chloride-lactic acid (with a molar ratio of 1∶2) has good antioxidant activity, and the antioxidant activity increases with the increase of rapeseed glucosinolate concentration. The scavenging rates of DPPH radicals, ABTS radicals and the reducing power of iron ions were the highest, which were 91.00%, 56.00% and 0.600 respectively, higher than those of rapeseed glucosinolate extracted by ethanol solution(with a volume fraction of 70%).