ABSTRACT
The major problem with spectrophotometric procedures is the insolubility of the lignin preparations. In order for the procedure to quantitatively assess total lignin concentrations, the sample must be completely solubilized so that an accurate measurement can be made. Permanganate has also been used to estimate lignin concentrations. In theory, permanganate oxidizes the lignin components leaving only the sugar residues behind. Lignin has also been determined by derivitization with thioglycolic acid. This method has gained popularity since the formation of lignothioglycolic acid was a reported characteristic of lignin. In many human foods, lignin is only found associated with spiral and annular bands in xylem-conducting vessels. Thus, lignin is a small component of the human diet since the more heavily woody tissues are not frequently consumed. Lignin appears to play an important role in ruminant fiber fermentation, limiting fermentation by presenting a physical barrier to bacterial access.
