System Development from Organic Solvents to Ionic Liquids for Synthesiz-ing Ascorbyl Esters with Conjugated Linoleic Acids

Zhiyong Yang, Lise Schultz, Zheng Guo, Charlotte Jacobsen, Xuebing Xu

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The aim of this paper is to screen suitable reaction systems for the modification of antioxidants through enzy-matic synthesis. Enzymatic esterification of ascorbic acid with conjugated linoleic acid (CLA) was investigated as a mod-el. Four organic solvents and five different enzymes were evaluated. Results show that only Novozym® 435 turned out to be a useful enzymatic preparation for the production of ascorbyl-CLA ester. The optimum reaction conditions in the or-ganic solvent system were 4 h at 55°C and at a molar ratio of 5 (CLA/ascorbic acid). The esterification reaction was trans-ferred to an ionic liquid system for the purpose of improving solubility of the polar substrate and avoiding the application of organic solvents. From screening experiments, it was evident that only methyltrioctylammonium triflouroacetate (tO-MA·TFA) could provide a proper reaction environment for production of ascorbyl-CLA ester when using Novozym® 435 as biocatalyst. It was possible to significantly increase the productivity (150 g/l) through the increase of ascorbic acid sol-ubility in ionic liquids by super saturation together with the increase of reaction temperature to 70°C, far beyond than that in organic solvents (35 g/l) after preliminary optimizations for both systems.
Original languageEnglish
JournalThe Open Biotechnology Journal
Volume6
Pages (from-to)5-12
ISSN1874-0707
DOIs
Publication statusPublished - 2012

Keywords

  • Ascorbic acid
  • CLA
  • Organic solvents
  • Ionic liquids
  • Esterification

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