Soluble sugar content was determined by anthrone-sulfuric acid colorimetric
method [20]. The 0.2 g dried sample was boiled in 10 mL distilled
water for 10 min and then quickly cooled on ice. The homogenate
was centrifuged at 8000 ×g for 15 min. The supernatant was transferred
to 25 mL test tubes with scale. The residue was extracted again, and the
supernatant was transferred to test tubes and was added with distilled
water up to 25 mL. 2 mL of the supernatant was mixed with 5 mL
anthrone-sulfuric acid, and the mixture was left at room temperature
for 20 min. Soluble sugar content was estimated from absorbance at
620 nm. The soluble sugar concentration was determined using a standard
curve, and results were expressed as % of dry weight (DW).