POLYPHENOLS IN PLANT, HUMUS, AND SOIL III. STABILIZATION OF GELATIN BY POLYPHENOL TANNING

Abstract

Summary The role of polyphenols in the stabilization of protein in superficial humus and the relationship of this role to mull and mor formation is discussed. Polyphenols extracted from a variety of plant materials were used to tan gelatin over a wide range of pH. The stability of gelatin, tanned with polyphenols extracted from green beech leaves (mor site), against microbial degradation was then estimated. Over the range of pH found in soils, stability was greatest when the pH of the tanning was low. It seems likely that mor‐forming plant species contain more efficient tannins and the acid condition of the associated soil is better suited to the tanning process. Quantitative differences in tanning substances between mull and mor sites have already been reported by us (Coulson et al., 1960a).