Title: ORIGIN OF SEED COAT FRAGMENT CONTAMINATION IN GINNED LINT Author
Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: January 4, 2005
Publication Date: January 7, 2005
Citation: Boykin Jr, J.C. 2005. Origin of seed coat fragment contamination in ginned lint. National Cotton Council Beltwide Cotton Conference. CD ROM pp. 745-755. Interpretive Summary: U.S. cotton production approaches 20 million bales annually, most of which is exported. It is important that the quality of this cotton keeps up with the changing demands of the industry. One issue that is becoming increasingly important is problems associated with cottonseed that rupture as the cotton is harvested and ginned leaving fragments in the cotton lint. Fragments of cottonseed in the cotton lint lead to problems in the textile mill when the cotton lint is spun into yarn. These fragments can cause the yarn to break resulting in costly down time in the mill. In addition, when the yarn or fabric is dyed, the fragments absorb the dye differently than the cotton lint and cause discoloration that is undesirable in the finished product. This preliminary research was conducted to identify the sources, either before the gin plant or within the gin plant, that were responsible for fragmenting the seed. Two cotton varieties were processed in Stoneville, MS through a typical sequence of machines and samples were taken at each step to analyze seed coat fragments. The gin stand was found to be a major source of seed coat fragments. It was indicated that a large number of seed coat fragments also originated before the gin stand and possibly before the gin plant, but these were only preliminary results. This knowledge will be vital to modifying harvest machinery, gin machinery, or cotton variety characteristics to reduce levels of seed coat fragment contamination in cotton lint. Implementation of this knowledge will increase the competitiveness of U.S. cotton.
Technical Abstract: Two cotton varieties, A and B, were ginned in the microgin at Stoneville, MS to track seed coat fragments (SCFs) as they were produced, altered, and removed by gin machinery. Bales of variety A contained 2100 grams of SCFs and 5460 grams of motes leaving the gin stand, and bales of variety B included 4500 grams of SCFs and 8110 grams of motes. For the two varieties tested, SCF weights were reduced 5.5% to 7% by the gin stand and 15% to 16% by one lint cleaner, and mote weights were reduced 15% to 17% by the gin stand and 40% to 47% by the lint cleaner. Several sources were thought to contribute to SCF contamination, but no one source clearly dominated. The number of SCFs found in seed cotton samples was not significant due to the high error associated with the measurement. Seed meat (embryo) counts were used to estimate that 3% of variety A SCFs and 9% of variety B SCFs leaving the gin stand originated before reaching the gin stand. The cottonseed for some cotton is damaged before reaching the gin plant releasing the seed meat from the seed coat which enters the seed roll at the gin stand with fibers attached. About half of the seed meats found in seed cotton were thought to originate from damage that occurred before entering the gin plant. A major source of SCFs appeared to be the gin stand where seed or immature seed were fragmented in the seed roll or passed the ginning ribs. Both the gin stand and the lint cleaner removed larger SCFs from the lint, and the lint cleaner fractured SCFs into smaller ones. A mote balance for both the gin stand and lint cleaner did not reveal any degradation of motes to SCFs, so they were not considered a major source. Some conclusions reached in this report were based on measurements with high levels of error, so results should be considered preliminary until the test is repeated.