Upland Cotton Surface Amino Acid and Carbohydrate Contents Vs. +b and L*a*b*

Currently, there is a problem in the cotton industry associated with fiber color development after harvest, and it is debated as to why this issue occurs, especially during storage and shipment.  Upland cotton is naturally white, with its yellowness (+b) rating influencing its worth.  Cotton can be shipped back to the supplier, or heavily discounted, if there are quality measurement discrepancies. Some previous studies have suggested that reactions between amino acids and carbohydrates on the surface of upland cotton fibers may lend to color development, and initial amounts of those constituents on the fiber surface after harvest may indicate potential future changes in +b ratings. This study used HVI, a portable spectrophotometer, ion chromatography and a ninhydrin test to compare amino acid and carbohydrate content of 45 Upland cotton samples with their color measurements: +b and L*a*b*.  A correlational statistical analysis found a quadratic relationship between amino acid content and +b; and highly positive correlations between amino acids and +b ratings: 0.8607; and b* values: 0.820 (p<0.05).  This research is proof-positive that surface amino-acids have some meaningful relationship to cotton’s +b color rating.