Analytical methods
A part of the coconut husk sample was
ground with a Wiley mill (Kinematica AG Co.
Ltd., Tokyo, Japan), then passed through a 420-
μm sieve prior to chemical analyses. The contents
of lignin, alphacellulose and hemicellulose were
determined using the Technical Association Pulp
and Paper Industry method (TAPPI, 1996). The
glucose and xylose contents were quantitatively
determined by high performance liquid
chromatography (HPLC) connecting to a refractive
index (RI) detector. An AMINEX HPX87P
carbohydrate analysis column (Bio-Rad, Hercules,
CA) was operated at 85°C using deionized water
as a mobile phase at 0.6 mL/min. Ethanol was
measured by gas chromatography (GC) using an
HP5890 Series II apparatus equipped with an
Agilent 6890 Series injector.