Cotton remains one of the most important natural fibers. Since cotton is produced in the field rather than at a manufacturing facility, it remains difficult to understand all chemical and physical properties that are affected by production, further processing, and utilization. Cotton color differences are not well understood chemically and the protective exterior complexity of raw cotton further entangles matters. This study will evaluate how cotton identified at the gin as sticky cotton may be affected by heat, acid catalysis, and water rinsing treatments to lower cotton stickiness. Cotton fiber physical deteriorations and discolorations are known to occur under these instances but little is understood in how the protective cuticle layer including pectins, waxes, and sugars affect fiber properties and future processing.

The cotton samples consisted of commercial upland varieties that were selected because of their wide range of stickiness levels. The various cottons consisted of commercial upland varieties from California and Syria, which were harvested, ginned, and baled by commercial methods. Several of these bales had previously been identified as potentially sticky and problematic cotton by the acid-base pH spray indicator test. Since the acid-base pH spray indicator is often not accurate in finding sticky cotton, these bales had been previously tested for stickiness on the minicard. The minicard is currently the best test for cotton stickiness. Sugar and other components of cotton’s protective cuticle layer have diverse melting points, varying degrees of hydrolysis, and can cause a multitude of chemical reactions. Fiber samples were sorted and separated for various treatments that have the potential to affect this layer. To evaluate the removal effectiveness and fiber properties of treatments, each sample was prepared for testing that included atomizing samples with 10 % citric acid, rinsing samples with 40

oC deionized water, or preparing a control. To evaluate differences among treated and untreated cotton samples, these cotton samples were either unheated or heated at 133 ^oC with steam or dry heat for 1, 2, and 4 h. Following these treatments, samples were tested for sugar content and HVI fiber properties. Sugar was measured using the glucose oxidase enzyme method. Cotton quality measurements were performed on the HVI that allows cotton fibers to be tested for length, strength, fineness, color and trash.

This study evaluated steps that could be taken at the cotton gin or textile mill to adequately remove sugar from cotton. Heat treatments, rinsing, and acid catalysis likely all affect the surface components and cotton fibers themselves. The lack of these surface components likely decreases the lubrication and the ease of future processing. Citric acid catalysis, water rinsing, and additional heat (both dry and steam) appear to lower cotton sugar levels. Glucose levels decreased for unheated samples from 24.4 to 6.1 mg/l by heating samples at 133 ^oC with dry heat for 4 h. Combining all heat treatments and water rinsing lowered glucose levels from 18.5 mg/l to 5.0 mg/l. Fiber quality decreases with steam, dry heat, and acid catalysis. Combining all heat treatments, the control’s fiber strength was 27.2 g/tex and samples treated with citric acid had a statistically lower strength of 26.1 g/tex while water rinsing had a statistically higher value of 29.6 g/tex. Water rinsing appears to be the most advantageous process to lower sugar levels while maintaining or improving fiber quality. No reliable relationship appears to currently exist with HVI results and cotton stickiness.