The content for the four species is
between 25 and 33 per 100 phenylpropane units (ppu), denoting
that the cleavage of these linkages is one of the main reactions
in the delignification process. Usually, O 4 content in lignin
preparations (isolating methods that partially preserve lignin
structure) is usually about 50/100 ppu (Costa et al., 2014). However,
quite different values have been reported for silver grass; for
example, You et al.