A rapid method for the measurement of Leucaena spp proanthocyanidins by the proanthocyanidin (butanol/HCl) assay

Dalzell, Scott A. and Kerven, Graham L. (1998) A rapid method for the measurement of Leucaena spp proanthocyanidins by the proanthocyanidin (butanol/HCl) assay. Journal of The Science of Food and Agriculture, 78 3: 405-416. doi:10.1002/(SICI)1097-0010(199811)78:3<405::AID-JSFA133>3.0.CO;2-G


Author Dalzell, Scott A.
Kerven, Graham L.
Title A rapid method for the measurement of Leucaena spp proanthocyanidins by the proanthocyanidin (butanol/HCl) assay
Journal name Journal of The Science of Food and Agriculture   Check publisher's open access policy
ISSN 1097-0010
0022-5142
Publication date 1998-11
Sub-type Article (original research)
DOI 10.1002/(SICI)1097-0010(199811)78:3<405::AID-JSFA133>3.0.CO;2-G
Volume 78
Issue 3
Start page 405
End page 416
Total pages 12
Place of publication Chichester, England
Publisher John Wiley & Sons on behalf of SCI.
Language eng
Subject 070303 Crop and Pasture Biochemistry and Physiology
Formatted abstract
Proanthocyanidin (PA) extraction, sample preparation and proanthocyanidin assay (butanol/HCl) reaction conditions were evaluated for measuring PA in Leucaena spp leaf material. The optimal conditions for extracting PA from leaf tissue are described, with short sequential sonications in 70% aqueous acetone being as efficient as prolonged sequential mechanical agitation. In methanol-based extracts, after back extraction to remove pigments, increasing the water content of the reagent/sample matrix suppressed colour development. The addition of low concentrations of Fe3+ to the butanol/HCl reagent enhanced colour yield, but higher Fe3+ concentrations suppressed colour development. The presence of ascorbic acid in the sample extract was shown to increase colour development. Varying the reagent : sample extract ratio from 4 : 1 to 6 : 1 significantly decreased colour yield, but neither ratio was different from 5 : 1. Optimum conditions for the PA assay were as follows: a water content of 8%, the omission of Fe3+, a reagent : sample extract ratio of 5 : 1 and the addition of ascorbic acid to the stock PA standard solution to match that contributed by the extract in the final mixture. Sample preparation procedures, using back extraction to remove pigments and non-PA phenolics with diethyl ether and ethyl acetate, respectively, were time-consuming and subject to PA losses. The measurement of PA directly in the 70% aqueous acetone extract eliminated these PA losses, but the PA assay required additional optimisation for direct analysis of crude acetone extracts. In the final optimised procedure, PA was extracted by sequential sonication with 70% aqueous acetone containing 5.26 mM sodium metabisulphite as the antioxidant. These extracts were directly analysed by the butanol/HCl reaction using a reagent : sample extract ratio of 5 : 1, the omission of Fe3+ from the butanol/HCl reagent and the addition of sodium metabisulphite to match that contributed by the extract. This produced consistent linear calibration curves over the range 25-1000 μg PA with an average recovery of 101%.
Keyword condensed tannin
proanthocyanidin
extraction
sample preparation
proanthocyanidin (butanol/HCl) assay
Leucaena
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Agriculture and Food Sciences
 
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