Rapid Quantification of Proanthocyanidins (Condensed Tannins) with a Continuous Flow Analyzer

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• 作者：James K. Nitao ; Bruce A. Birr ; Muraleedharan G. Nair ; Daniel A. Herms ; and William J. Mattson
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2001
• 出版时间：May 2001
• 年：2001
• 卷：49
• 期：5
• 页码：2207 - 2214
• 全文大小：99K
• 年卷期：v.49,no.5(May 2001)
• ISSN：1520-5118

文摘

Proanthocyanidins (condensed tannins) frequently need to be quantified in large numbers of samplesin food, plant, and environmental studies. An automated colorimetric method to quantify proanthocyanidins with sulfuric acid (H₂SO₄) was therefore developed for use in a continuous flow analyzer.Assay conditions were optimized using 50% methanol extracts of paper birch, sugar maple, andquaking aspen leaves. Short extraction times and centrifugation of samples prevented proanthocyanidin degradation that otherwise occurred in 50% methanol extracts of aspen leaves. Extractionof birch and maple proanthocyanidins with 50% methanol was comparable to or better than thatwith 70% acetone. Proanthocyanidin levels in aspen were lower when extracted with aqueousmethanol, but relative differences among samples were consistent with those found in aqueousacetone extracts. Results from the automated sulfuric acid assay were highly correlated with thoseof the conventional BuOH-HCl method for proanthocyanidins and, except for birch, with the Folin-Denis assay for total phenolics. This new technique significantly improves assay processing rateand repeatability compared to conventional colorimetric proanthocyanidin assays.Keywords: Proanthocyanidins; condensed tannins; colorimetric assay; Betula; Acer; Populus