NIR spectroscopic analysis
All samples were measured using a PerkinElmer Frontier NIR
spectrophotometer in transmission mode in the wavelength range
from 700 to 2500 nm, at 2 cm1 resolution and using a 1 cm optical
path length. Prominent absorption peaks appeared in the region
from 700 to 1100 nm, corresponding to the second and third overtones
of the OH stretching vibration and to the third overtone of
CH2 and CH stretching [27].