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Gravimetric determination of tannins and their correlations with chemical and protein precipitation methods
Author(s) -
Makkar Harinder P S,
Blümmel Michael,
Borowy Norbert K,
Becker Klaus
Publication year - 1993
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740610205
Subject(s) - tannic acid , tannin , gravimetric analysis , chemistry , precipitation , chromatography , polyvinylpyrrolidone , proanthocyanidin , protein precipitation , colorimetry , polyphenol , food science , organic chemistry , mass spectrometry , antioxidant , physics , meteorology
Abstract. A method for gravimetric determination of tannins based on binding with insoluble polyvinylpyrrolidone (PVP) is presented. The gravimetric method gives the absolute amount of tannins and avoids problems of standards associated with spectrophotometric methods. The method was applied to nine browse and tree leaves. The values obtained correlate significantly with tannins determined spectrophotometrically, protein precipitation capacities and protein precipitable phenotics. This method together with other tannin assays will be useful in nutritional studies. The present study also demonstrates the different behaviour of tannic acids from different commercial sources towards PVP suggesting the presence of different moieties in tannic acids from different commercial sources and even among batches from the same source thereby affecting the results obtained using the spectrophotometric methods. Use of well‐defined tannic acid as a standard in spectrophotometric methods is suggested which will allow meaningful comparison of values obtained from different laboratories.