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- Co, Michelle,1975-Uppsala universitet,Institutionen för kemi - BMC (author)
Degradation effects in the extraction of antioxidants from birch bark using water at elevated temperature and pressure
- Article/chapterEnglish2012
Publisher, publication year, extent ...
- Elsevier BV,2012
- printrdacarrier
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- LIBRIS-ID:oai:DiVA.org:uu-132344
- https://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-132344URI
- https://doi.org/10.1016/j.aca.2011.04.038DOI
- https://lup.lub.lu.se/record/2517339URI
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- Language:English
- Summary in:English
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- 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 El 80, contained birch bark extracts obtained after extraction at 80 and 180 degrees 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 degrees 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 degrees 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 degrees 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 degrees 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.
Subject headings and genre
- NATURVETENSKAP Kemi Oorganisk kemi hsv//swe
- NATURAL SCIENCES Chemical Sciences Inorganic Chemistry hsv//eng
- NATURVETENSKAP Kemi Analytisk kemi hsv//swe
- NATURAL SCIENCES Chemical Sciences Analytical Chemistry hsv//eng
- Degradation
- Pressurised fluid extraction
- Antioxidants
- DPPH assay
- Electrochemical detection
- Diode-array detection
- Tandem mass spectrometry
- Elevated temperature
- Birch bark
- Chemistry
- Kemi
- Inorganic chemistry
- Oorganisk kemi
- Analytical Chemistry
- Analytisk kemi
- Kemi med inriktning mot oorganisk kemi
- Chemistry with specialization in Inorganic Chemistry
- Birch bark
- spectrometry
- Elevated temperature
- Antioxidants
- DPPH assay
- Electrochemical detection
- Diode-array detection
- Tandem mass
- Pressurised fluid extraction
- Degradation
Added entries (persons, corporate bodies, meetings, titles ...)
- Zettersten, CamiliaUppsala universitet,Institutionen för kemi - BMC (author)
- Nyholm, LeifUppsala universitet,Oorganisk kemi(Swepub:uu)lny18455 (author)
- Sjöberg, Per J.RUppsala universitet,Analytisk kemi(Swepub:uu)psj18455 (author)
- Turner, CharlottaLund University,Lunds universitet,Uppsala universitet,Institutionen för kemi - BMC,Centrum för analys och syntes,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Centre for Analysis and Synthesis,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH(Swepub:lu)orga-cht (author)
- Uppsala universitetInstitutionen för kemi - BMC (creator_code:org_t)
Related titles
- In:Analytica Chimica Acta: Elsevier BV716, s. 40-480003-26701873-4324
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