Durian peel of 10% (w/v) was hydrolyzed in autoclave at 121°C
for 15-60 min, with 0.5 to 2% (v/v) of H2SO4, HCl and H3PO4. The
hydrolysis samples were centrifuged at 3,000 rpm for 20 min. The
solid fraction was washed with distilled water and dried in hot air
oven at 70°C until constant weight was obtained. Then, weight of
percentage of acid hydrolysis efficiency (AHE) was calculated using
the following equation. The supernatant was collected and determined
for reducing sugar, using dinitrosalicylic acid (Bernfeld, 1955)
and total sugar, using phenol sulfuric acid (Hansen and Phillips,
1981). The maximum amount of total sugar from hydrolysate was
determined for morphology by SEM and sugar polymers through
high performance liquid chromatography (HPLC), using a YMCPack
Polymine II column (conditions: 1.0 ml / min, 25°C).