Tea Leaves by Francis Leggett
page 48 of 78 (61%)
page 48 of 78 (61%)
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tannin in tea infusion, milk, when added, neutralizes the
coagulating power of the tannin entirely or to such degree as to render it harmless. Professor Johnston thinks it quite probable that tannin takes some part in the exhilarating effect of tea, and in that of the betel-nut of the East. While the astringent influence of strong tannin upon the bowels is regarded as unfavorable, hot tea infusion has with many persons a contrary effect, stimulating the peristaltic movements and antagonizing constipation. If tannin is injurious, it should be observed that its proportion in the leaf of green teas is very much larger than in Black teas. An analysis by Mulder gave as the percentage of tannin in a Black tea, 12.85 per cent., and in a green tea as 17.80 per cent. But another analysis made by Y. Kazai, of the Imperial College of Agriculture of Japan, made the per centage of tannin (gallo- tannic acid) in a Green tea 10.64, and in a Black tea from the same leaf 4.89. In the green leaf from which these teas were derived he found 12.91 per cent. of tannin. This analysis indicates also that a portion of the tannin disappears in manufacturing Green tea, but a still larger, proportion is lost or changed in the manufacture of Black tea. Tannic acid taken into the human stomach in large quantity produces, according to the U.S. Dispensatory, "only a mild gastro-intestinal irritation." Passing over the phosphoric acid, the gluten, and other interesting constituents of the tea leaf, we proceed to the |
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