Peer review

The amount of protein precipitated by tannin under a variety of conditions is measured by using radioiodinated protein. The protein is mixed with purified tannin, finely ground plant tissue, or an unpurified plant extract; the mixture is centrifuged to remove the insoluble tannin- protein complex. An aliquot of the supernatant layer is counted to calculate the amount of protein precipitated. Complex formation is dependent on the pH and solvent composition. Tannin specific activity is useful for comparing tannin from various sources and for monitoring tannin purification. It is defined here as the ratio between the amount of protein precipitated and the amount of oxidizable material present.

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