Abstract:

The purpose of this study was to investigate the optimum ultrasonic-assisted extraction process and antioxidant
activity of polysaccharides from lotus leaves. A comparison between the ultrasonic-assisted extraction and the traditional
water extraction was carried out. The key factors affecting extraction efficiency and their interactions were explored based on
a central composite design. The optimum conditions for ultrasonic-assisted extraction were determined as 200 W, 22:1, 39 min
and 76 ℃ for ultrasonic power, water-to-lotus leave ratio, extraction time and temperature, respectively. The extraction yield
of polysaccharides under these conditions was 4.25%, which was over 40% higher than that obtained with the traditional water
extraction method, while the extraction time was shortened by 56.7% using the ultrasonic-assisted extraction method. Moreover,
antioxidant polysaccharides with significantly higher activity were obtained from ultrasonic-assisted extraction.

Key words: lotus leaves, polysaccharides, ultrasonic-assisted extraction, response surface analysis, antioxidant activity