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Degradation effects in the extraction of antioxidants from birch bark using water at elevated temperature and pressure.
- Source :
-
Analytica chimica acta [Anal Chim Acta] 2012 Feb 24; Vol. 716, pp. 40-8. Date of Electronic Publication: 2011 Apr 27. - Publication Year :
- 2012
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Abstract
- Experiments with birch bark samples have been carried to enable a distinction between extraction and degradation effects during pressurised hot water extraction. Two samples, E80 and E180, contained birch bark extracts obtained after extraction at 80 and 180°C for up to 45 min, respectively. Two other samples, P80 and P180, were only extracted for 5 min at the two temperatures and were thereafter filtered and hydrothermally treated at 80 and 180°C, respectively. During the latter treatment, samples were collected at different times to assess the stability of the extracted compounds. An offline DPPH (2,2-diphenyl-1-picrylhydrazyl) assay, as well as a high performance liquid chromatographic separation coupled to an electrochemical detector, were used to determine the antioxidant capacity of the processed samples. The results obtained with the different techniques were compared to assess the yield of the extraction and degradation processes. In addition, an online hyphenated system comprising high performance liquid chromatography coupled to diode-array; electrochemical; and tandem mass spectrometric detection (HPLC-DAD-ECD-MS/MS) was used to study the compositions of the extracts in more detail. The results for the samples processed at 80°C showed that the extraction reached a steady-state already after 5 min, and that the extracted compounds were stable throughout the entire extraction process. Processing at 180°C, on the other hand, gave rise to partly degraded extracts with a multitude of peaks in both the diode array and electrochemical detectors, and a higher antioxidant capacity compared to for the extracts obtained at 80°C. It is concluded that HPLC-DAD-ECD is a more appropriate technique for the determination of antioxidants than the DPPH assay. The mass spectrometric results indicate that one of the extracted antioxidants, catechin, was isomerised to its diastereoisomers; (+)-catechin, (-)-catechin, (+)-epicatechin, and (-)-epicatechin.<br /> (Copyright © 2011 Elsevier B.V. All rights reserved.)
- Subjects :
- Antioxidants isolation & purification
Catechin isolation & purification
Chromatography, High Pressure Liquid
Electrochemical Techniques
Plant Bark chemistry
Pressure
Stereoisomerism
Tandem Mass Spectrometry
Temperature
Antioxidants chemistry
Betula chemistry
Catechin chemistry
Water chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 1873-4324
- Volume :
- 716
- Database :
- MEDLINE
- Journal :
- Analytica chimica acta
- Publication Type :
- Academic Journal
- Accession number :
- 22284876
- Full Text :
- https://doi.org/10.1016/j.aca.2011.04.038