| Abstract |
- The structural component compositions of thirty nine non-commercial Pacific
Northwest grasses were analyzed in order to develop a database of the grasses that
may have application in bioconversion processes. The samples were chosen based on
near infrared reflectance (NIR) data that suggested this group of grasses, collectively,
was representative of the broad range of compositions that are likely to be encountered
due to genotypic and phenotypic variability. Solvent-extracted samples were prepared
by extracting the native grass sequentially with water and then 95% ethanol. Each of
the grasses residues was analyzed for glycans (glucans, xylan, and arabinan), acidinsoluble
lignin, acid soluble lignin, and ash.
Total glycans ranged from a low of 32% to a high of 50%. Glucan was the
major glycan component, typically in the range of 60%. Xylan represented about onethird
of the total glycans which is 9.5% to 18.3% while arabinan represented 1.0% to
3.3%. Total glycans seemed to increase from the younger stage to the more mature
stage. The mean total glycans of the vegetative stage was 32%, while that of the seed mature stage was 45.9%. While the amount of glycans varied between species, the
ratio of glucan, xylan, and arabinan (12: 7: 1) remained relatively constant.
Acid-insoluble lignin ranged from 6.38% to 14.58%, while the acid-soluble
lignin ranged from 1.57% to 4.35%. The acid-insoluble lignin of seed mature, flower,
boot, and vegetative stages were 12.38%, 11.65%, 9.39%, and 8.10%, respectively.
The acid-soluble lignin of seed mature, flower, boot, and vegetative stages were
2.03%, 2.6 1%, 3.02%, and 3.46%, respectively. Extractives represented 20,29% to
41.55% of the oven-dry grasses. The ash values of the unextracted grasses ranged
from 5% to 10% while the ash values for the extracted samples were typically in the
range of 0.5% to 2.5%, showing that the sequential water and ethanol extractions
tended to remove 60 80% of the quantifiable inorganic matter from the grasses.
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