1.4.1 R eliable Methods for Determining Lignin

as a Component of Dietary Fiber

In any enzymaticgravimetric method, DF as oligo- and polysaccharides that are nonhydrolyzable by the specific enzymes are usually recovered along with lignin and

other associated substances, such as waxes, cutin, and suberin from 78 percent alcohol.

In the enzymaticchemical method, only the constituent sugars and lignin represent DF. However, there is no accurate method for routine measurement of lignin,

whose structure as a phenyl-propanoid polymer has not been well defined. Klason

lignin determined by AOAC method 994.13, as the acid insoluble organic matter in

the DF residue, may include some tannins and Maillard reaction products. A modified

permanganate method has been shown to be more reproducible and the values

are lower when compared with those obtained after acid detergent fiber extraction

followed by permanganate treatment or after Klason lignin treatment.18