LigninGehalt

Ligningehalt, or lignin content, refers to the proportion of lignin in plant materials, usually expressed as a percentage of dry matter. Lignin is a complex phenolic polymer that fills spaces in the plant cell wall among cellulose, hemicellulose, and other biopolymers. It provides structural support, contributes to water transport, and acts as a chemical barrier against pathogens. Because lignin is resistant to enzymatic degradation, its abundance strongly affects the digestibility of forage and the efficiency of biomass conversion.

Measurement of lignin content commonly uses the Klason method, which quantifies acid-insoluble lignin after sulfuric acid hydrolysis, and the acid detergent lignin (ADL) assay used in forage analysis. Other approaches estimate lignin content indirectly from lignin-derived phenolics or via spectroscopic techniques. Values are typically reported as weight percent of dry matter.

Variation in lignin content occurs across species, tissues and age. Softwoods (gymnosperms) generally have higher lignin contents than hardwoods (angiosperms). Within a plant, woody tissues and bark often contain more lignin than leaves or young shoots. Environmental conditions and genetics influence the degree of lignification.

Applications and implications: In the pulp and paper industry, high lignin content reduces pulping yield and whiteness, guiding the choice of pulping process and bleaching strategies. In animal nutrition, high lignin decreases forage digestibility. In bioenergy and biorefinery contexts, lignin contributes to biomass recalcitrance, affecting pretreatment and conversion efficiency; research explores modifications to lignin content and composition through processing and plant breeding without compromising plant health.