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United States Department of Agriculture

Agricultural Research Service

Title: Chemical and Structural Properties of Kenaf Cell Types Related to Enzymaticretting

Authors
item Akin, Danny
item Morrison Iii, Wiley
item Rigsby, Luanne
item Dodd, Roy - CLEMSON UNIV AG & BIO ENG
item Raymer, Paul - UGA CROP & SOIL SCIENCE

Submitted to: American Chemical Society Symposium Series
Publication Type: Proceedings
Publication Acceptance Date: July 30, 1998
Publication Date: N/A

Interpretive Summary: There is great interest in using natural fibers for a variety of industrial purposes to add value to agricultural crops. Bast fibers, such as kenaf, are a potential source of industrial fibers, but separation of fibers from the stems, a process called retting, limits the efficient and economic collection of fibers. Researchers at the Russell Research Center, in collaboration with scientists at the University of Georgia and Clemson University, evaluated factors that could improve retting and add value to this crop. Results indicated that lignification of fiber bundles limits the fiber size to a coarse fiber. Younger plants retted more easily than older ones, and combined crimping and enzymatic retting with cellulases and xylanases produced clean fiber bundles. These data show the potential to add value to kenaf by using an environmentally friendly process of retting, namely enzymatic retting.

Technical Abstract: Kenaf (Hibiscus cannabinus L.) cultivars Tainung 2, Everglades 41, and SF 459 at 30, 60, 90, 120, and 180 days post planting were characterized to provide fundamental information towards the goal of developing value-added products. Cultivars were similar to each other in constituents within harvest time, but all varied due to increased maturity. Bast and core fractions were considerably lignified by 30 days, and increases did not occur after 60 to 90 days as shown by gas-liquid chromatographic analysis. Bast had a high ratio of syringyl to guaiacyl lignin, a finding verified by histochemistry. In bast, xylose and glucose amounts increased with age, but other carbohydrates varied in concentration. Histochemistry and ultraviolet absorbance microspectrophotometry of bast showed that only fibers were lignified; middle lamellae contained more aromatics than secondary layers in tightly bound fiber within bundles. Enzymatic retting of bast at all harvest ages was very inefficient, but mechanical pretreatment (i.e., crimping) of bast ribbons and use of enzyme mixtures resulted in considerable retting of 180 day Tainung 2. An enzyme mixture of xylanases and cellulases separated fiber bundles, and not individual fibers, and resulted in clean bundles without considerable non-fiber material as shown by scanning electron microscopy.

Last Modified: 11/27/2014
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