A3403

Glucose, fructose, and sucrose were extracted from the ground samples using a modified method of Zhao et al. (2010) . Briefly, a mixture of 30 mg dried tissue was extracted three times with 80% (v/v) ethanol in an 80 °C water bath for 15 min. Extracts were centrifuged and supernatants were combined, filtered through 0.45 μm pore size nylon membranes, and 20 μl were used for glucose, fructose, and sucrose analysis by HPLC (Shimadzu Corp., Kyoto, Japan) with a refractive index detector (Model RID-10A). The mobile phase consisted of 80% (v/v) acetonitrile in water with a flow rate of 1 ml min⁻¹. A Luna 5 µm NH₂ 100 Å, LC Column 250 × 4.6 mm from Phenomenex (Torrance, CA, USA) was used for the analysis which, was performed with the column maintained at 40 °C. Data acquisition was controlled by LabSolutions software (Shimadzu Corp.).
The pellets remaining from the above extractions were used for starch solubilization according to Zhao et al. (2010) . α-Amylase (Sigma-Aldrich, A3403) and amyloglucosidase (Sigma-Aldrich, A3042) were used to hydrolyse the pellets. The glucose content was assayed as described above by HPLC and used to calculate starch concentration.

Commercial α-amylase (Bacillus licheniformis, A3403, Sigma) was added into the 1% (w/v) soluble starch and this mixture was incubated at 90 °C for 30 min. Then the mixture was incubated at 100 °C for 20 min to inactivate the enzyme, and centrifuged at 12,000× g for 15 min. After adding 5 ug recombinant GSJ or commercial α-glucosidase (Bacillus. Stearothermophilus, E-TSAGS, Megazyme, Ireland), the supernatant was incubated at 60°C. Following incubation for 1 h, the mixtures were incubated at 100 °C for 5 min to inactivate the enzyme, and centrifuged at 12,000× g for 15 min. The hydrolysis products were determined by HPAEC.