Study On Fermentation Condition For Compositive Pectinase And Their Characteristics

Through submerged fermentation, The conditions for the pectinase production by Aspergillus niger were optimized. The results showed that the optimal medium for Polygalacturonase(PG) production was (g/L): wheat bran 60, citrus peel powder 40, (NH₄)₂SO₄2O, K₂HPO₄·3H₂O 3, KCl 6, MgSO₄·7H₂O 5.5. The optimal cultural conditions were: initial pH 4.0, 30°C, seed volume 6%, 50mL/250mL for 3 days. The enzyme activity was 523.7U/mL; Pectinesterase(PE): wheat bran 45, pectin 30, (NH₄)₂NO₃ 15, K₂HPO₄·3H₂O5, KCl 7, MgSO₄·7H₂O5, initial pH 5.0, 28°C, seed volume 7%, 50mL/250mL for 3 days. The enzyme activity was 76.7 U/mL. Petin lyase(PL): wheat bran 60, cornstalk 40, carbamide 20, K₂HPO₄·3H₂O 2, KCl 7, CaCO₃ 10, initial pH 6.0, 30°C, seed volume 8%, 50mL/250mL for 2 days. The enzyme activity was 8.47 U/mL.Their property were also studied. The results showed that the optimal temperature of PG was 45°C. Its optimal pH was 4.0, It was steady from 2.0 to 7.0; The optimal temperature of PE was 50°C. Its optimal pH was 5.0, It was steady from 5.0 to 8.0; The optimal temperature of PL was 50°C. Its optimal pH was 6.0, It was steady from 4.0 to 8.0.Through filtration,centrifuge and ultrafiltration, We obtained concentrated fermented broth of PG,PE and PL. We tested their stability. The results showed that PG and PE were more stable in room temperature than 30°C, but PL was opposite. Their remnant enzyme activity was 70.28%,77.24%,74.45% when conserved ten days respectively. They were compared to commercial enzyme. The enzyme activity of concentrated fermented broth was higher than commercial enzyme, PG and PL were outstanding. But their property was uniform. Lastly, They were all treated in apple juice yield. The enzyme showed remarkable improvement in the apple juice yield, and enzyme that maded by ourselves was better than commercial enzyme.