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NIR Transmittance Estimation of Free Lipid Content and Its Glycolipid and Digalactosyldiglyceride Contents Using Wheat Flour Lipid Extracts¹

¹Cooperative investigations, USDA, Agricultural Research Service, and the Department of Grain Science and Industry, Kansas State University. Contribution 98-480-J from the Kansas Agricultural Experiment Station, Manhattan, KS 66506. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. ²Graduate research assistant and professor, respectively, Department of Grain Science and Industry, Kansas State University, Manhattan, KS 66506. ³Present address: USDA-ARS, Grain Marketing and Production Research Center, Manhattan, KS 66502. ⁴Supervisory research chemist, USDA-ARS, Grain Marketing and Production Research Center, Manhattan, KS 66502. ⁵Corresponding author. Phone: 785-776-2703. Fax: 785-537-5534. E-mail: okchung@usgmrl.ksu.edu

Free lipids (FL) in 72 hard winter wheat flours were extracted and dissolved in hexane. Absorbance (log 1/T) values were measured using a scanning spectrophotometer with a 2-mm cuvette, and used to develop calibration models for estimating flour FL content and glycolipid (GL) and digalactosyldiglyceride (DGDG) contents. Fifty-one calibration samples were selected based on the cutoff point of 0.3 of Mahalanobis distance, and the remaining twenty-one samples were used for validation. The best model for the estimation of FL content showed coefficients of determination (R²) of 0.95 for the calibration set and R² = 0.89 for the validation set. Glycolipid contents could be estimated by a model which had R² = 0.87 for the calibration set and R² = 0.89 for the validation set. For DGDG, the best model showed R² = 0.94 for the calibration set and R² = 0.88 for the validation set.