Multivariate analysis of coconut residues by near infrared spectroscopy

Near infrared (NIR) spectroscopy was used to determine the content of Klason lignin, acid-soluble lignin, total lignin, extractives, ash, acid-insoluble residue, glucose, xylose, rhamnose, galactose, arabinose, mannose and total sugars in coconut residues. The samples were analyzed at several processing stages: wet unground (WU), dried unground (DU) and dried and sieved (DS). Partial least squares models were built, and the models for the analytes exhibited R(2)>0.80, with the exceptions of rhamnose, arabinose, galactose, mannose and ash from all fractions, and the lignin content from the WU fraction, which were predicted poorly (R(2)<0.70). There were some significant differences between the models for the main lignocellulosic components at the various stages of biomass. These results proved that NIR spectroscopy is useful for analysis at biorefineries, and it can be used as a faster and more economical alternative to the standard methods.