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.

Introduction

Contents

Tannin chemistry

The biological activities of tannins

Evaluating antioxidants

Purification of tannins

Characterization of tannins

Estimating quantities of phenolics

Estimating quantities of tannins (functional group methods)

Estimating quantities of tannins (protein precipitation methods)

Characterizing tannin-protein interactions