The process which microwave is applied to dynamic multi-stage countercurrent extraction

namely the process of microwave dynamic multi-stage countercurrent extraction (MDMCE)

for extracting dihydromyricetin from Ampelopsis grossedentata was investigated.Comparison of MDMCE and microwave static batch extraction (MSBE) demonstrated that both the driving force of mass transfer and extraction efficiency of MDMCE were higher than those of MSBE.The optimum extraction conditions of 5 stages MDMCE obtained by orthogonal design were as follows：10 min extracting time for 5 stages MDMCE（2 min for every stage）

110 ℃

1∶30 material to solvent ratio

600 W microwave power. Under these conditions the extraction yield of dihydromyricetin and percentage of dihydromyricetin in residue were 92.2 % and 3.1% respectively. A kinetic model of single vessel for MDMCE was developed and the functional relation between dihydromyricetin concentration and extraction time was ln(ΔC)=0.2985lnt-12.52.