Optimization of Ultrasonic Extraction of Polysaccharides in Lingyun Pekoe and Its Antioxidant Activity

Lingyun pekoe as starting material, studies were carried out to optimize the extracting technology of polysaccharides, and investigate its antioxidant activity. Extracting yield of polysaccharides as the index, the extraction conditions were optimized by Box-Bohnken method based on the results of single-factor experiments. The antioxidant activities were evaluated by the determination of hydroxyl radical (·OH), 1,1-Diphenyl-2-picrylhydrazyl radical (DPPH·) , and inhibition effect on auto-oxidation of grease. Experimental results showed that, the optimal extraction conditions were obtained as follows: liquid-material ratio 69:1 mL/g, temperature 52 ℃, ultrasonic time 21 min, ultrasonic power 180 W. Under the optimal conditions, an average extraction yield (4.84%±0.04%) was obtained, which was similar with the expected yield 5.06% (<5%) of regressive equation. The IC₅₀ of polysaccharides for eliminating ·OH, DPPH· were 0.262, 0.438 mg/mL, and a better clearance result would be obtained with higher concentration. Moreover, polysaccharides could prolong the storage time of grease in normal circumstance for inhibiting the auto-oxidation. The studies mentioned above indicated that polysaccharides were plentiful in Lingyun poeke, and had a good antioxidant activity, providing data support for promoting in home and abroad.