"In our previous work, we demonstrated how lignin condensation and precipitation taking place in kraft pulping can be
detected and even quantified by Fourier Transform Infrared (FTIR) spectroscopy. Because lignin reactions in acid
sulfite pulping are very different from those occurring during kraft cooking, a new analysis method is proposed to
rapidly analyze the condensed lignin in acid sulfite pulp. This kind of analysis is useful for sulfite pulp mills to detect
the elevated risk of black cook. This paper presents and discusses the novel method using FTIR spectroscopy to rapidly
analyze lignin condensation in softwood pulp samples from acid sulfite processes. Several softwood pulp samples from
acid sulfite pulping at varying levels of condensation were included in this research. According to the results, FTIR
spectroscopy allows indirect quantification of lignin condensation in a difficult matrix of wood constituents, such as in
incompletely delignified acid sulfite pulp."