Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2000
Publication Date: 6/6/2000
Citation: Brushwood, D.E., Han, Y.J. Possible NIRS Screening Tool for Entomological Sugars on Cotton Fiber. 2000. Journal of Cotton Science. v. 4 (3), p 137-140.
Interpretive Summary: High levels of natural sugars and contamination from whitefly and aphid honeydew found on the surfaces of harvested cotton lint can have confounding effects on textile processing. Stickiness in the form of highly concentrated sugary deposits accumulate on machinery sometimes making processing virtually impossible. Two very sticky sugars, trehalulose and melezitose, have been identified to be unique to whitefly and aphid contaminated cottons. Standard sugar analysis in conjunction with physical stickiness tests such as the thermodetector or minicard tests are very good predictors of potentially sticky cottons. These tests, however, are difficult to integrate into a rapid on-line classing system. The potential for the use of the Near Infrared (NIR) measurement as a quick non-destructive on-line screening tool to identify insect contamination wa investigated in this study. A single non-insect contaminated Upland cotton was treated with different concentrations of these sugars and mixtures. NIR, moisture resistance meter, and oven moisture measurements were conducted on treated and untreated samples at four different conditioned relative humidities. A discriminant analysis procedure to classify the concentrations of insect sugars on the cotton was successful when integrating fiber moisture content into the regression analysis. This study may serve as a basic model for further development and refinement of a rapid on-line test to detect and quantitate insect honeydew on cotton lint.
Technical Abstract: Non-insect contaminated cottons were treated with different concentrations of two sugars identified as unique to insect honeydew. Trehalulose (a disaccharide), the most predominant sugar found on heavily contaminated whitefly cottons, and melezitose (a trisaccharide), found on both whitefly and aphid contaminated cottons, contribute substantially to the stickiness potential of cotton lint. High performance liquid chromatography (HPLC) analysis of extracts from these cottons to identify and quantitate individual carbohydrate concentrations, chemical sugar analysis to determine reducing sugars present, Thermodetector (TD) stickiness measurements, and near infrared (NIR) spectra scans were run to characterize untreated and treated cottons that were subsequently conditioned to four different fiber moisture levels. Statistical analysis using chemical analysis and NIR spectra data results in the selection of twelve wavelengths and the fiber moisture content as independent variables in multiple regression equations to predict concentrations of entomological sugars on these cottons. Poor predictability was obtained looking at the overall range of fiber moistures from 4.6 to 9.3%. When the calculations were divided into specific moisture ranges, linear correlation coefficients of predictability increased significantly. A discriminant analysis procedure was able to classify cotton samples into two classes of the entomological sugar contents with 89.2% success ratio.