Alkali-soluble Lignin Research Articles

Disappearance of Hemicellulosic Monosaccharides and Alkali-Soluble Phenolic Compounds of Normal and Brown Midrib Sorghum × Sudangrasses Fed to Heifers and Sheep

Eight yearling Holstein heifers (330kg) were utilized in two 4×4 Latin squares. Diets were normal and brown midrib genotypes of Redlan×Greenleaf and Redlan×Piper varieties of ensiled first-cutting sorghum-sudangrass harvested at early head stage of maturity. Composition of hemicellulosic monosaccharides and alkali-soluble lignin phenolic compounds in feeds and corresponding digestibilities were estimated. Arabinose, xylose, and uronic acids were more digestible in brown midrib genotypes than in normal genotypes. p-Coumaric acid disappearance was higher in heifers consuming normal genotypes than in those on brown midrib mutants.In a second experiment, four Suffolk wethers with ruminal, duodenal, and ileal cannulae were utilized in a 4×4 Latin square design. Diets were second-cutting sorghum-sudangrass harvested at prehead stage of maturity as baled hay. Digestibilities were determined in the same manner as for heifers. Brown midrib genotypes had higher hemicellulosic monosaccharides, galactose, and uronic acids than did normal genotypes. Xylose content of the brown midrib mutant of Redlan×Piper was higher than that of the corresponding normal genotype. Total tract galactose digestibility was higher in brown midrib genotypes than in normal genotypes. Total tract hemicellulose digestibility (estimated by summing fractional digestibilities of hemicellulosic monosaccharides) was higher in brown midrib mutants than in normal genotypes.

Correlation between physical and chemical changes of rice straw as a major constituent under composting

We studied composting on a laboratory scale with rice straw as a major constituent and some nutrients, to correlate physical and chemical changes during the composting. We found that the change of the degree of decay, defined in this paper, which is an effective measure of the physical change, correlated clearly to changes of total nitrogen, C/N ratio, cold water soluble lignin, and alkali soluble lignin, which are major chemical properties of compost. The correlation coefficients were higher than r = 0.92 for the C/N ratio, water soluble lignin, and alkali soluble lignin. These chemical measures will be useful as simple indices of the maturity of compost.

Chemical Studies on Tue Wood of Declining Conifers

The soluble components in the wood of conifers (Picea abies, Pinus sylvestris) of different damage c1asses from various sites in Bavaria have been studied. Fresh sapwood wassqueezed and the sap analysed for the amounts of carbohydrates as weil as for the pH value. The investigation of the alkali extracts included the determination of carbohydrates and lignin. Changes in the composition related to tree disease can only be observed in strongly damaged or dead trees. In these cases the pH value and the amounts of the main sugars (fructose, glucose) decrease and the amount of the oligosaccharides increases. In some spruce trees of high damage classes the alkali-soluble lignin also increases. The ex ternal appearance of a tree does not reflect its in temal condition in all cases.

Comparison of Wheat Straw Lignin Preparations. II. Straw Lignin Solubilisation in Alkali

In order to understand the characteristic solubility of Gramineae ligins in alkali, three lignin fractions were extracted from wheat straw: an alkali-soluble lignin LA, a milled-straw lignin LM and an enzyme lignin LE. Molecular size distributions were compared by size exclusion chromatography on mu-Bondagel, and acidic groups (carboxylic and phenolic groups) were estimated by potentiometric titration. The molecular size distribution of alkali lignin LA was intermediate between those of LM and LE. Solubilisation of wheat straw lignin by alkali treatments may thus result from depolymerisation to molecular weights of the same order as those obtained by ultragrinding. Alkali lignin was found to be significantly richer in acidic groups than LM or LE. It is concluded that Gramineae lignins differ from hardwood and softwood lignins by a relatively higher content of alkali-labile linkages within the lignin network or between lignin and polysaccharides.