[Study on gallic acid preparation by using immobilized tannase from Aspergillus niger].

Immobilized tannase which had higher ability of transforming tannin from Chinese gallotannin into GA was prepared by embedding tannase with calcium alginate carrier. The immobilization conditions and some properties of the immobilized tannase were studied. The results showed that: The optimal immobilized parametres were 90 mg sodium alginate, 546 u(182 u/mL) tannase and 1%-2% CaCl2. The optimum temperature and pH value of immobilized tannase were 45 degrees C and 6.5, respectively. It was stable in the temperature range of 10-50 degrees C and between pH5-7. Based on the optimum program, the laboratory gramme-grade preparation experiments of GA were done. The average yield of GA product in three preparations was upto 61%, and was about equivalent to the yield of acidic hydrolytic method which is used to produce GA industrially now. Thus, the research results possessed potential applied value.