|Morrison Iii, Wiley|
Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/3/1998
Publication Date: N/A
Citation: Interpretive Summary: Flax is the source of linen and is a commercially important crop in Europe; interest in flax/linen is gaining in the US. The quality of dew-retted flax fiber is determined by expert graders and buyers using subjective evaluations. At present there are no objective, analytical methods for the determination of quality. This study employed light microscopy, chemical and instrumental methods of analysis to obtain objective data which could be related to quality. Light microscopy revealed bits of material which indicated inefficient retting, the process which separated the fibers from core. Higher quality, more efficiently retted material, contained less of this material and had greater separation of fibers and fiber bundles. Chemical and instrumental analysis identified as waxes and cutin and provided quantitative data. From these initial results, cutin and waxes appeared to be a potential marker for quality assessment in flax and linen. None of the methods alone presented the whole picture and will have to be used on a more extensive set of samples to provide a clearer picture of the relationship of chemical constituents to quality. This information will provide a more objective measurement of quality and information as to what chemical constituents are modified during retting and processing that are related to quality.
Technical Abstract: Flax fiber and yarn samples that had been commercially graded low, medium, and high quality were analyzed by light microscopy, wet chemical analysis, Raman spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy to determine the characteristics which could be related to quality ratings. Light microscopy revealed fragments of cuticular and epidermal material bound to the fibers. As the quality ratings improved, fewer of these fragments were found and greater separation of the fiber bundles to smaller bundles and, in some cases, elementary fibers occurred indicating more efficient retting. Chemical evaluation showed that, as quality increased, amounts of fatty acid and long chain alcohols as well as dihydroxy fatty acids decreased. Raman spectroscopy showed increasing amounts of cellulose and decreasing amounts of aromatics and hydrocarbons with increasing quality, which paralleled the chemical data. NMR analysis showed nearly equal amounts of crystalline cellulose within the fibers and yarn, regardless of quality. The strengths and weaknesses of each analytical method are discussed. This initial study suggested that chemical constituents characteristic of cutin and waxes could be used as an initial marker of quality.