2013 Volume 82 Issue 1 Pages 63-68
The starch content of tea plant was measured by the colorimetric iodine method (iodine method) after hot-water extraction. The maximum absorbance of starch extracted from tea roots was around 600 nm, and extraction with hot-water for at least 10 minutes was considered sufficient for accurate measurement. The starch content measured by the iodine method was compared with that measured by the phenol-sulfuric acid colorimetric method in which starch was extracted with perchlorate (control method). The starch content in roots and stems measured by the iodine method was closely correlated with the value obtained by the control method (r=0.98). However, in samples with a low starch content (less than 30 mg g-1), the value obtained by the iodine method was lower than that obtained by the control method. As compared with the control method, the time and cost required for analysis were reduced to 1/3 and 1/90, respectively, by the iodine method. Moreover, harmful chemicals are not used in the iodine method. It is concluded that the iodine method is an easy-to-use and safe method to accurately measure the starch content of tea plants.
