FTIR microspectroscopic approach to investigate macromolecular distribution in seed coat cross-sections

Cotton seed coat neps (SCNs) are among the least cleanable impurities in textile industry. SCNs can cause problems by persisting into yarn and fabric, reducing yarn strength, increasing yarn ends-down, and even resulting in uneven dye uptake. The study presented herein investigated the effects of the cultivar on the seed coat contamination using a suite of analytical techniques. The cultivar with more SCNs showed a significantly higher average fiber detachment force, and had a significantly larger number of seeds that required a higher force (> 8 N) for fiber detachment compared to the cultivar with less SCNs. The seeds with a strong fiber-seed attachment could lead to breakage of the seed coat during ginning and produce more SCNs. Fourier transform infrared (FTIR) spectroscopy analysis revealed differences in the biochemical composition in the outer epidermal layers of cotton seeds where the fibers are attached. k-mean cluster analysis of FTIR images and their functional group distribution images revealed that the outer layers and the palisade layer of the seed coats had major differences in molecular concentration and distribution that could contribute to cultivar dependence of SCNs. This study could lead to better understanding of the effects of the cultivar on the generation of SCNs.