Optimization of Ultrasonic and Enzymatic-assisted Extraction of Polysaccharides from Eucommia ulmoides Oliver Leaves by Response Surface Method

In order to enhance the extraction efficiency of polysaccharides from Eucommia ulmoides Oliver leaves, the ultrasonic and enzymatic-assisted extraction technology of Eucommia ulmoides Oliver leaves polysaccharide was studied. Firstly, the effects of multienzyme complex dose, pH, extraction temperature, ultrasonic power, ratio of liquid to solid and extraction time on the polysaccharide yield as the index were investigated. Secondly, a Plackett-Burman design was adopted to screen the significant factors that were further involved into a steepest ascent experiment. Finally, a Box-Behnken experiment was designed to optimize the extraction process. The results showed that the multienzyme complex dose, pH and ultrasonic power were the significant factors (P<0.05), and their significance was in order of pH > ultrasonic power > multienzyme complex dose. The optimal extraction conditions were as follows:Multienzyme complex dose of 3.7%, pH4.0, ultrasonic power of 100 W, extraction temperature of 45℃, liquid to solid ratio of 20:1 mL/g and extraction time of 15 min. Under these conditions, the experimental yield of extracted polysaccharides was 4.79%±0.02%, close to the theoretical one of 4.87%. The results showed that, compared with the traditional extraction process, the ultrasonic and enzymatic-assisted extraction process could extract Eucommia ulmoides Oliver leaves polysaccharides rapidly and efficiently, which greatly reduces the extraction cost and is of great significance for the industrial production of Eucommia ulmoides Oliver leave polysaccharides.