Oxidative Changes of Polyphenols as Influenced by Allophane1
- Kazutake Kyuma and
- Keizaburo Kawaguchi2
Oxidative changes of polyphenols as influenced by allophane were studied in relation to humus-forming processes in Ando soils. A chestnut tannin-containing substrate was incubated for varying lengths of time with an allophanic material, and changes in the shape of ultraviolet (UV) and infrared (IR) spectra and in neutralization capacity of the polyphenols were traced with time. As compared with control materials, the allophanic material adsorbed large amounts of organic carbon (8 to 10 times as much at the end of 22 weeks), and the adsorbed organic matter kept incubated for only 2 weeks showed the following features: (1) No sharp peaks in UV spectrum at the 280 mµ region which is characteristic of tannin, (2) High optical density (about 20 times as high at 400 mµ as that of tannin), (3) High neutralization capacity (416 me. per 50 g. carbon, which is about 3 times as high as that of tannin), and (4) Strong 5.8 to 5.9 µ band in IR spectrum instead of a weak shoulder as for tannin. All these remarkable changes occurring in a very short period of time suggested that allophane might have some catalytic effect on oxidative changes of polyphenols, and a manometric determination of oxygen absorption confirmed this supposition. Such catalytic effect exerted by allophane would have great significance in humus formation and accumulation in Ando soils.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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