Upland Cotton Surface Amino Acid and Carbohydrate Contents vs. Color Measurements

Abstract

Upland cotton is naturally white, with its yellowness (+b) rating highly influencing its economic value. Field conditions, microorganisms, and growth problems can cause cotton to become discolored at harvest, which has historically been thought to indicate a decrease in product quality. Previous research has suggested that some reactions between amino acids and carbohydrates on the surface of cotton fibers may lead to color development after harvest during certain storage and shipping conditions. There has been a lack of research evidence to understand how initial amounts of those surface constituents present at harvest may indicate the propensity for potential future changes in +b ratings. Due to the monetary implications, it is important for those in the cotton industry to better understand exactly how detrimental the +b value is on the functionality of the cotton. This study aimed to identify potential relationships between the post-harvest surface amino acids and carbohydrates content with color rating values to gain insight using High Volume Instrument (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, Rd, 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).