AbstractThe tannin content of over‐the‐counter Indian tea, of green coffee beans and of the roasted coffee beans prepared from the same green beans was determined with a radial diffusion ‐ protein precipitation technique and with a spectrophotometric method. The green beans contained 6.6 ± 0.6 mg g−1weight tannic acid equivalents as found by protein precipitation (n= 5, ± SD) or 6.8 ± 2.3 mg g−1by spectrophotometry. The same figures for roasted beans were 18 ± 1.7 and 17 ± 2.7 mg g−1, respectively. Tea contained 37 ± 2.6 mg g−1weight tannic acid equivalents as analysed by spectrophotometry and 24 ± 2.8 mg g−1by the protein precipitation technique. The latter finding may show that the biological reactivity of tannins is variable, although no major changes in the tannin‐precipitated albumin occurred as shown by electrophoretic analysis. Both methods provide an easy analysis of the reportedly ca
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