Because they are composed of a variety of chemical components, pitches are possessed of highly scattering properties. Therefore, the spectra of pitches obtained by FT-IR have large backgrounds, and the backgrounds have a detrimental influence on the accuracy of analysis. Recently, the diffuse reflection method has been widely used for analyzing pitches, although it has been pointed out that the method has some problems; for example, diffuse reflection cannot obtain very sharp absorption peaks. In this paper, new dilution materials are developed and proposed that allow one to obtain fine spectra of pitches. With the use of our dilution materials, the shapes of absorption peaks become more sharp, the intensities of the peaks increase considerably, and the backgrounds of those spectra are reduced to a large extent. The quality of the spectra of the pitches is considerably improved. Our method may prove to be a solution for dealing with the problem posed by backgrounds, which have heretofore seriously affected accuracy in the analysis of spectra.
FT-IR spectroscopy as a tool for the study of the quality of processed meat products