The Tannin Handbook

Copyright 1998, 2002, 2011 Ann E. Hagerman. All rights reserved.

Ann E. Hagerman

http://chemistry.muohio.edu/hagerman

Introduction

This handbook was originally published for use in the Hagerman laboratory. The original printed Tannin Handbook is no longer available; please print pages that you need from this site.

All of the methods have been published in the primary literature, and it is strongly recommended that each individual attempting to perform these methods first refer to the original literature to obtain a better understanding of the utility and limitations of the methods. The results of these analyses are only meaningful when they are interpreted with a full understanding of the chemistry underlying the analysis.

Major limitations on all methods of tannin analysis are the different responses given by different phenolics; and the difficulty of procuring an appropriate standard. Differential response means that "tannin level" or "phenolic level" of a sample cannot be adequately expressed as a single value. Differential response prevents use of any single commercially available compound as a convenient standard, since the relative response of the standard and the analyte in the assay are not known. To overcome these difficulties, several methods based on different chemistries should be employed to obtain a qualitative and quantitative picture of the tannins present in the mixture. Either the tannin of interest should be purified for use as a standard, or a well characterized standard should be prepared and used with a good understanding of the limitations.

Methods used for quantitative analysis of tannins can be classified as follows:

*      General phenolic methods

*      Functional group methods

*      HPLC

*      Protein precipitation methods

Contents

Tannin chemistry

 


What is a Tannin?

Condensed Tannin Structural Chemistry

Hydrolyzable Tannin Structural Chemistry

Biosynthesis-Some References

Tannin Bibliography

The biological activities of tannins

Biological Activity of Tannins

Tannins as Metal Ion Chelators

Tannins as Antioxidants

Protein Digestibility

Protein Precipitation

Evaluating antioxidants

Deoxyribose Assay

Metmyoglobin Method

Purification of tannins

Tannin Purification

Extraction of Phenolics from Plant

Sephadex LH 20

Separation of Tannin from Nontannin Phenolics

Fractionation of Tannic Acid

Gallotannin Purification

Pentagalloyl Glucose

PGG preparation modification

Purification of Sorghum Tannin

Purification of standard procyanidin (dimer) from apple

Purification of Quebracho Tannin

Chemical Modification of Tannins

Characterization of tannins

HPLC of Gallotannins

Normal Phase HPLC of Gallotannins

Isocratic Reversed Phase HPLC of Gallotannins

Reversed Phase HPLC of Gallotannins

Condensed Tannin HPLC

Thiolysis procedure for proanthocyanidins

Phloroglucinol Method - HPLC

TLC of Tannins

Estimating quantities of phenolics

General Phenolic Methods

Modified Prussian Blue Assay

Prussian blue assay for total phenols-microplate format

Prussian Blue Assay

Estimating quantities of tannins (functional group methods)

Functional Group Methods

Condensed Tannin Methods

Acid Butanol Method

Acid Butanol Method Modified with PVP

Acid butanol method for dried fruit samples

Vanillin Assay

Modified Vanillin Assay

Vanillin-Acid Butanol Ratio for Degree of Polymerization

Hydrolyzable Tannin Methods

Gallotannin Determination with Rhodanine

Determination of Hydrolyzable Tannins after Reaction with Potassium Iodate

Determination of Ellagitannins

Phlorotannin Determination

Estimating quantities of tannins (protein precipitation methods)

Protein Precipitable Phenolics

Protein precipitable phenolics for microplate reader

Radial Diffusion Assay

Modified Radial Diffusion Assay

Selective Radial Diffusion Assay

Precipitation of Phlorotannin by Protein

Characterizing tannin-protein interactions

Radiolabeled BSA Precipitation Method

Blue BSA Method

Electrophetic Detection of Tannin-binding Proteins

Silver Stain for Electrophoresis Gels

Coomassie Stain for Electrophoresis Gels

BCA protein assay for microplate reader

NBT staining for quinoprotein