FTIR microspectroscopy as a tool to investigate the origin of seed coat fragment generation and its dependency on cotton cultivars

Cotton is known as white gold due to its naturally occurring cellulosic textile fibers, which are used as a raw material in the textile industries and have a significant annual economic impact. The United States is a prominent exporter and producer of cotton fiber. Cotton always has some waste along with its fibers, such as neps, stem, leaf, hull, bark, seed coat fragments, etc. Seed coat fragments (SCFs) are among the most problematic trash particles in cotton because of their strong attachment to fibers. SCFs impact fiber quality and hamper the aesthetic appearance of cotton fabric because they lead to yarn breakage, neps formation, and uneven dye uptake. The majority of SCFs are produced during the ginning process when a set of rotating saw teeth pull the fibers from seeds to separate them. It has been reported that the formation of SCFs is cultivar dependent. In this study, we investigate the cause of seed coat generation. Fifteen commercial cotton cultivars with various levels of seed coat contaminations (AFIS data) were selected. First, we measured the fiber detachment force of seed cotton using a tensile tester and shear strength using a seed shear tester. We identified that cultivars with more SCFs showed a significantly higher fiber detachment force. Thus, we selected four cultivars with major differences in SCFs count, shear strength, and fiber detachment force for further physio-chemical characterization. The surface morphology of cotton seed coats of these cultivars was visualized using scanning electron and polarized light microscopes. Additionally, TGA confirmed the presence of cellulosic and non-cellulosic compounds in seed coats. Then, we examined changes in chemical concentration and distribution of biomolecules in seed coats using Fourier Transformed Infrared (FTIR) spectroscopy, chemimaps, and k-mean clustering of FTIR images. Compared to cultivars with lower levels of SCFs, cultivars with more SCFs displayed higher concentrations of hemicellulose, protein, pectin, lignin, and cellulose. This research could contribute to providing a new insight into the causes of SCFs generation.

Embargo status: Restricted until 01/2024. To request the author grant access, click on the PDF link to the left.