Antioxidative properties and enzymatic synthesis of ascorbyl FA esters
Abstract Efficient synthesis of unsaturated FA esters of ascorbic acid is possible with only a small excess of one of the reactants in t ‐amyl alcohol using Candida antarctica lipase as biocatalyst. Using free acids, we obtained yields that were comparable to yields reached using vinyl‐activated acy...
| Published in: | Journal of the American Oil Chemists' Society |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Wiley
2003
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1007/s11746-003-0774-1 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1007%2Fs11746-003-0774-1 https://onlinelibrary.wiley.com/doi/full/10.1007/s11746-003-0774-1 |
| Summary: | Abstract Efficient synthesis of unsaturated FA esters of ascorbic acid is possible with only a small excess of one of the reactants in t ‐amyl alcohol using Candida antarctica lipase as biocatalyst. Using free acids, we obtained yields that were comparable to yields reached using vinyl‐activated acyl donors (71, 80, and 86% yields of esters with FA excesses of 1∶1, 1∶1.5, and 1∶2, respectively). As very low water activity is needed to achieve sufficiently high yields of product, molecular sieves were used to improve the ascorbyl ester yields. Ascorbyl oleate is more amorphous and has a much lower m.p. and lower enthalpy of fusion than ascorbyl palmitate. This leads to a higher solubility of ascorbyl oleate in oil, resulting in an increased antioxidant effect compared to that of the palmitate. In an accelerated storage test using deodorized rapeseed oil, samples incubated with ascorbyl palmitate showed noticeable oxidation after 1 wk of storage, whereas samples incubated with ascorbyl oleate displayed negligible oxidation for 9 and 4 wk at 30 and 40°C, respectively. |
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