Abstract:

Inulin was extracted by using enzyme hydrolysis method from burdock (Arctium lappa L.) root. The optimum extraction conditions were as follows: neutral protease content 13.5 g/100 mL, pH 7, solid/liquid ratio 1:15, hydrolysis time 6h, temperature 50 ℃. The yield of inulin under the optimum conditions was 14.57%. A 2.5 g/100 mL solution of chitosan in 1% aqueous acetic acid was prepared which contained 7.5 mg/mL of neutral protease, and then it was poured, dropwise, into a suspension medium consisting of 40% formaldehyde and 2 mol/L of NaOH at the volume ratio of 2:3 at 60℃ and pH 7.5. The immobilization time was 8 h. And the recovery of enzyme activity was 39.13%. The optimum extraction conditions using immobilized enzyme were as follows: pH 7, solid/liquid ratio 1:15, hydrolysis temperature 60 ℃, immobilized enzyme 13.5 g/100 mL. Under such conditions ,the yield of inulin was 12.89%. After 10 times continuous reaction, the yield of inulin decreased to 9.42%, which indicated that the stability of the immobilized enzyme was significantly improved.

Key words: burdock, inulin, neutral protease, chitosan, immobilized enzyme