Chemical composition of components comprising bast tissue in flax

Area of Science:

• Plant biochemistry
• Textile science
• Analytical chemistry

Background:

• Flax retting is crucial for fiber extraction.
• Identifying reliable markers for retting degree and fiber quality is essential.
• The chemical composition of flax stem layers influences processing.

Purpose of the Study:

• To identify chemical markers for predicting flax retting degree and fiber quality.
• To analyze the chemical constituents of flax outer layers and fiber bundles.
• To evaluate the suitability of dihydroxy fatty acids, fatty acids, alcohols, sterols, and aromatics as retting markers.

Main Methods:

• Hand separation of flax stem components (outer layer and fiber bundles).
• Enzymatic treatment of the outer layer to isolate cuticle.
• Gas chromatography and mass spectrometry (GC-MS) for chemical analysis.
• Quantification of dihydroxy fatty acids, long-chain fatty acids and alcohols, sterols, and aromatics.

Main Results:

• Dihydroxy fatty acids were predominantly located in the outer layer (98-99%), making them strong retting markers.
• Long-chain fatty acids and alcohols were also concentrated in the outer layer (80-92%).
• Aromatics and sterols showed variable distribution and were less reliable for retting assessment.
• 8,16- and 9,16-dihydroxyhexadecanoic acids constituted the majority (87-89%) of the measured dihydroxy fatty acids.

Conclusions:

• Dihydroxy fatty acids, particularly 8,16- and 9,16-dihydroxyhexadecanoic acids, are excellent chemical markers for flax retting degree.
• These dihydroxy fatty acids, as components of the cuticle, can also potentially indicate fiber quality.
• The distribution of chemical constituents in flax stem layers provides insights into retting processes.