关键词: 微乳凝胶, 单宁酶, 没食子酸酯, 没食子酸转化率

Abstract: Alkygallate is a kind of antioxidant and possesses patient therapy value. However, it was synthesized by chemical method, whichhas defects of serious circumstance containment and low productivity. To avoid these defects, the method of biosynthesis for alkygallates was established using microemulsion-based-gels(MBGs) andgallic acid was esterificated catalytically with different alcohols by tannase immobilized in microemulsion-basedgels,from which propylgallate (PG), butylgallate (BG) and amylgallate (AG) were successfully synthesized. Salt-salthydrate (Na₂SO₄-Na₂SO₄·10H₂O) could control and regulate water activity effectively, the ability was related to amount of salt-salthydrate. The conversion ofgallic acid was improved significantly when salt-salthydrate was added into reaction system. The conversion ofgallic acid reached 78.2% and 85% respectively when pH value was 6 and amount of Na₂SO₄-Na₂SO₄·10H₂O(ratio 1:1) was 1.8 g under the temperature of 28℃ in MBGs reaction systems for PG synthesis and BG synthesis, compared to the control, increasing by 93.0% and 129.7%,respectively. The conversion ofgallic acid reached 72.4% when pH value was 6 and amount of Na₂SO₄-Na₂SO₄·10H₂O(ratio 1:1)was 2.4g under the temperature of 28℃ in MBGs reaction system for AG synthesis, compared to the control, increasing by 103.7%.

Key words: microemulsion-based-gels, tannase, alkyl gallate, conversion of gallic acid