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Quantitative Characterization of Polar Lipids from Wheat Whole Meal, Flour, and Starch

¹Department of Grain Science and Industry, Kansas State University, Manhattan, KS 66506. ²Present address: Laboratory of Food Chemistry and Biochemistry, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, B-3001, Leuven, Belgium. ³Division of Biology, Kansas State University, Manhattan, KS 66506. ⁴Corresponding author. Phone: +1.785.532.5320. Fax: +1.785.532.7010. E-mail: jfaubion@ksu.edu

Lipids constitute only a minor proportion of total flour components but the composition and structure of wheat flour polar lipids influence the end-use quality of bread. So it is important to determine which specific lipid class and molecular species are present in wheat. Lipid profiling is the targeted, systematic characterization and analysis of lipids. The use of lipid profiling techniques to analyze grain-based food has the potential to provide new insight into the functional relationships between a specific lipid species and its functionality. The objective of this study was to utilize lipid profiling techniques to quantitatively determine the polar lipid species present in whole wheat meal, flour, and starch. Two commonly grown wheat cultivars, Alpowa and Overley, were used in this study. Direct infusion electrospray ionization tandem mass spectrometry was used to identify and quantitatively determine 146 polar lipid species in wheat. The predominant polar lipid classes were digalactosyldiglycerols, monogalactosyldiglycerols, phosphatidylcholine, and lysophosphatidylcholine. ANOVA results concluded that the wheat fraction contributed a greater source of variation than did cultivar on total polar, total phospholipid, and total galactolipid contents. Wheat whole meal, flour, and surface starch contained greater concentrations of total galactolipids, whereas internal starch lipids contained greater concentrations of monoacyl phospholipids. This research provides evidence that lipid profiling will provide the ability to determine the functional relationships between specific lipid species and the impact on end-use quality.