Isolation and Analysis of Lignin–Carbohydrate Complexes Preparations with Traditional and Advanced Methods

This review discusses various methods for the isolation and characterization of lignin–carbohydrate complexes (LCC) with a focus on the structures and quantities of the main linkages between lignin and carbohydrates. The advantages and limitations of different wet chemistry methods and nuclear magnetic resonance (NMR) spectroscopic techniques are indicated, and the optimal use of these techniques is suggested. The identification and quantification of the main LCC linkages in softwoods and hardwoods has recently become possible due to the application of high-resolution quantitative two-dimensional and 13C NMR techniques in the analysis of LCC. However, the NMR data should be complemented with analytical information generated by appropriate wet chemistry techniques, which provide critical insights into the carbohydrate sites involved in LCC linkages. Achievements in the LCC analysis are summarized, and important issues to be addressed in further studies are indicated.