Wheat straw pulps prepared by chemical (soda) and biological (enzymatic or fungal) treatments were analyzed by C-13 CP/MAS NMR spectrometry under quantitative acquisition conditions. The most significant changes reflected in the spectra as a result of soda cooking correspond to: (i) decrease of methoxyl content of the residual lignin (56, 153, 147 and 135 ppm), and (ii) deacetylation of hemicellulose fractions and saponification of cinnamyl esters concomitant to the release of alkali-soluble fractions (21 and 172 ppm). Reaction time was the factor with the greatest bearing on the former process, whereas soda concentration and temperature play an additional role in the latter The decrease of the methoxy/aryl ratio both after chemical and biological pulping suggests preferential removal of S-type lignin units. The comparison between quality parameters of die pulps and the C-13 NMR integration data suggests that rite linkage breakdown between straw macromolecules has a greater influence on paperboard properties than the near extent of rite chemical and biological removal of lignin fractions. (C) 1997 Elsevier Science Ltd.