Abstract: In the present study,a focused microwave-assisted solvent extraction method was developed for the removal of cellulose in Eucommia ulmodies seeds shell,followed by solvent extraction of gutta-percha.A L₉(3⁴) orthogonal factorial design for the optimization of removal conditions was used to evaluate the influence of four parameters,namely irradiation time,NaOH concentration,solvent volume and microwave power,on removal efficiency of cellulose.Then,the material obtained after removing cellulose was utilized to extract gutta-percha.Results indicated that the optimized conditions for the removal of cellulose were as follows:irradiation time of 20 min,12.5% NaOH solution as extraction solvent,17.5 mL solvent per gram material and 70% microwave power.Compared with the conventional NaOH extraction method,the proposed method possessed higher extraction efficiency for gutta-percha,with a value of 64.18% for a single circle,in a much less time (less than 3.0 h for the proposed method and about 30 h for the conventional one),with a comparable purity of gutta-percha.These results implied that the focused microwave-assisted extraction method was a promising method for the extraction of gutta-percha.

Key words: gutta-percha, microwave-assisted extraction, Eucommia ulmoides seeds shell, solvent extraction