© 2004 Heron Publishing—Victoria, Canada
A method for routine measurements of total sugar and starch content in woody plant tissues
Pak S. Chow (1) and Simon M. Landhäusser (1, 2)
1. Centre for Enhanced Forest Management, Department of Renewable Resources, University of Alberta, Edmonton, AB, T6G 2E3, Canada / 2. Corresponding author (simon.landhausser@ualberta.ca) / Received December 15, 2003; accepted February 15, 2004; published online August 2, 2004
Summary
Several extraction and measurement methods currently employed in the determination of total sugar and starch contents in plant
tissues were investigated with the view to streamline the process of total sugar and starch determination. Depending on the
type and source of tissue, total sugar and starch contents estimated from samples extracted with 80% hot ethanol were significantly
greater than from samples extracted with a methanol:chloroform:water solution. The residual ethanol did not interfere with
the sugar and starch determination, rendering the removal of ethanol from samples unnecessary. The use of phenol–sulfuric
acid with a phenol concentration of 2% provided a relatively simple and reliable colorimetric method to quantify the total
soluble-sugar concentration. Performing parallel sugar assays with and without phenol was more useful for accounting for the
interfering effects of other substances present in plant tissue than using chloroform. For starch determination, an enzyme
mixture of 1000 U α-amylase and 5 U amyloglucosidase digested starch in plant tissue samples more rapidly and completely than
previously recommended enzyme doses. Dilute sulfuric acid (0.005 N) was less suitable for starch digestion than enzymatic
hydrolysis because the acid also broke down structural carbohydrates, resulting in overestimates of starch content. After
the enzymatic digestion of starch, the glucose hydrolyzate obtained was measured with a peroxidase–glucose oxidase/o-dianisidine reagent; absorbance being read at 525 nm after the addition of sulfuric acid. With the help of this series of
studies, we developed a refined and shortened method suitable for the rapid measurement of total sugar and starch contents
in woody plant tissues.
Keywords:
acid hydrolysis, analysis, colorimetric, enzymatic digestion, ethanol extraction, MCW extraction, phenol–sulfuric acid.
