Abstract: Taking the grape fruit residue as raw material, the type of low eutectic solvent, microwave power, molar ratio and liquid to solid ratio as investigation factors, and the extraction rate of procyanidins as evaluation index, the microwave-assisted eutectic solvent was used to optimize the extraction process of procyanidins from grape fruit residue, and the stability of the extracted procyanidins was investigated. The results showed that under the condition of microwave power 420 W, extraction time 40 s, extraction temperature 40 ℃, liquid to solid ratio 40∶1, and choline chloride/glycerin at molar ratio 1∶2 as extraction agent, the extraction yield reached 19.57%. Procyanidins were stable at pH≤2, with a retention rate of more than 85%; the retention rate of procyanidins was more than 80% after 5 h at 4 ℃, but the retention rate decreased with the temperature increased; the retention rate of procyanidins decreased significantly to below 90% after 2 h due to the oxidant （H₂O₂）, and the decrease trend was more obvious with the increase of oxidant concentration; reducing agent （vitamin C） had a protective effect on procyanidins. When the concentration below was 0.32 g/L, its retention rate was more than 80% in 3 h; metal ions could destroy procyanidins except Zn²⁺, and Zn²⁺ could maintain the retention rate of procyanidins at about 80%; after fluorescent lamp irradiation for 5 h, the retention rate of procyanidins decreased to 60%, but the retention rate of procyanidins stored under dark light was 80%.

Key words: low eutectic solvent, procyanidins, extraction process, stability